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Are there any psychological studies of thirst following food that account for SFO-Nos1 activity?

Are there any psychological studies of thirst following food that account for SFO-Nos1 activity?

Some studies up to 2015 surprising found that salty vs. non-salty food doesn't make much difference to thirst. E.g. a 2015 study found that:

However, according to Prof. Leshem, despite our gut feeling that salt increases drinking, this relationship has not been studied in conditions simulating salt-rich foods such as savory appetizers. Therefore, in the present study involving 58 student participants, Prof. Leshem sought to investigate the effect of salt in solid foods on drinking. Participants were scheduled to come to the lab every few days after not having eaten or drunk anything except water, and not having smoked, for two hours. On the days they came, they were asked to taste nuts -- one time sugary candied nuts, another time salted nuts, and yet a third time nuts with no additives. They rated their level of thirst and, during a couple of hours in which they responded to various questionnaires, they got bottles of water. Each subject could drink as much water as he or she wanted.

The main finding was that the level of reported thirst and the actual quantity of water that the subjects drank after eating salty nuts were not different than following consumption of candied nuts or nuts without added flavors. To more deeply examine a possible correlation, the researchers selected the 10 male and 10 female students who had consumed the largest quantities of salt (an average of 4.4 grams and 3.7 grams respectively) and sought to determine whether within this subgroup there was a connection between thirst and drinking, but here too no such correlation was found. This means that even those subjects who consumed larger quantities of salt did not drink more.

This despite the well-known osmotic mechanism that promotes thirst in response to salt intake, and which is verified experimentally in humans, when using hypertonic vs isotonic infusions.

A 2016 study in Nature sheds some light on this issue, basically finding that, in mice at least, SFO-Nos1 neurons anticipate any changes in actual osmotic response; the longer the mice ate, the thirstier they got, well before there were any osmotic changes detected by their brains. Alas, these changes were only detectable using optogenetic photometry, not some non-invasive techniques like fMRI.

So, I'm curious if there are any (post-2016) human studies of thirst due to food ingestion (of various kinds) that attempt to account for the multiple [animal] neural pathways that trigger thirst (which very likely have an equivalent in humans.) E.g. we now expect that thirst might get [almost] equally great eating any kind of peanuts (salty or sweet) in a short time frame, but maybe there's a difference in thirst in a medium (or at least slightly longer) time frame between salty and non-salty peanuts.


1 Evolutionary explanations can also examine the historical roots of a feature, trait, or behavior. For example, the human hand is quite similar to the hands of other great apes, and the differences between primates can be traced in the bones of now extinct species linking the current species. In this article, we focus on the functional, not the historical, aspect of evolutionary explanations.

2 Of course, there are transformations. Elderly people are less likely to devote attention to mating effort, and such effort in postmeno-pausal females would no longer have direct reproductive consequences.

Declaration of Conflicting Interests

The authors declared that they had no conflicts of interests with respect to their authorship or the publication of this article.


On the psychology of drinking: Being thirsty and perceptually ready.

The concept of motivation is central to the understanding of why animals, humans included, initiate, select, and persist in specific actions. Researchers from various branches in psychology have examined the motives that instigate us to attend to, and interact with, our external environment (Bindra, 1974 Geen, 1995 Toates, 1986 Young, 1961). It is known that physical and social needs or motives point us to specified incentive stimuli (e.g. water, money, friends), and, as one possible criterion, it is the effort to explore these stimuli that qualifies the behaviour as motivational. For instance, the way we act on the primary motive of thirst nicely exemplifies the fundamental role of motivation in affecting the direction of subsequent behaviour. Out of several possible responses and stimuli that we have at our disposal, for example, we take a glass of water to quench our thirst.

In order to learn more about basic processes underlying the initiation of motivated human action, thirst and behaviour aimed at reducing thirst have been given much empirical attention (Fitzimons, 1972 Logue, 1991 Rolls & Rolls, 1982). Research aimed at understanding thirst itself has been largely concerned with the associated physiological changes. Cannon (1932), for instance, assumed that 'local body signs' play a role in thirst. Cannon conducted experiments on himself and observed an association between the sensation of a dry mouth and the experience of thirst. However, later research showed that a dry mouth is not normally the primary stimulus for thirst. Thus, wetting the mouth does not by itself reduce thirst (Bellows, 1939). Instead, thirst is also produced by general (instead of local) dehydration. That is, intracellular dehydration (e.g. caused by salt-intake), in which body fluid is lost from the cells, leads to thirst. Also, extracellular dehydration (e.g. due to loss of blood), in which fluid is lost from the compartments outside the cells, triggers thirst (Gilman, 1937 Stricker, 1966). Dehydration excites a complex pattern of neural activity in the hypothalamus and higher regions in the cortex (Grossman, 1979 Stellar, 1990) which in turn, lead to drinking and, in humans, reported thirst.

While the work alluded to above sheds light on the importance of physiological events (and mediating neural substrates) causing thirst and drinking, our present focus is on the psychology of thirst. We can all witness that thirst -- defined in terms of physiological changes -- results in behavioural changes such as drinking. The onset of drinking behaviour may result from various motivational and cognitive processes that can elicit these actions. Our goal here was to investigate whether inducing feelings of thirst increased cognitive accessibility of drinking-related cues.

The hypothesis that feelings of thirst leads to heightened accessibility of cues related to drinking is based on the following considerations. We assume that frequent and habitual implementation of a particular behavioural choice (e.g. taking a glass of water, drinking a bottle or can of soda) in order to regulate (the physiological changes that typify thirst increases the strength of the association between these two elements. Once these associations have been developed, thirst can prime action-relevant stimuli, thereby increasing their availability as cues (cf. also Gallistel, 1990). That is, due to instrumental learning, thirst is able to enhance the cognitive accessibility of items (e.g. glass, bottle, and water) that are instrumental in the course of reducing the desire to drink. In a recent review of learning research on the role of internal and external factors in ingestive behaviour Mook (1996) argued that '. hunger and thirst enhance, or, as we say, potentiate, the responses to relevant stimuli. The more potentiation from inside, the less effective the external stimulus has to be to trigger ingestion' (p. 91). Thirst, then, is expected to lead to perceptual readiness (cf. Bruner, 1957) aimed at reducing this thirst.

The idea that thirst causes internal representations of instrumental stimuli to become more accessible is consistent with contemporary animal learning research on the relationship between motives and action (Bolles, 1972 Colwill & Rescola, 1986 Dickinson & Balleine, 1994). Studies with hungry and thirsty rats, for instance, suggest that after a period of training the performance of instrumental actions is mediated by knowledge of the contingency between the action (e.g. pressing a lever) and the outcome or goal (e.g. getting water). Goal-directed actions are thus said to correspond to internal representations of performing that action. Hence, the arousal of primary needs may prime these representations in the service of satisfying the needs.

Although there is no hard evidence pointing to the conclusion that thirst leads to perceptual readiness aimed at reducing this thirst, there is some earlier evidence suggesting that primary motives (such as hunger) are capable of affecting human perception. In a test of the projective expression of needs, McClelland and Atkinson (1948) demonstrated that 16 hours of food deprivation activate eating-related thoughts. These researchers used an ostensibly subliminal perception task (they actually projected empty slides on a screen), and asked participants specific questions about the slides (e.g., 'What kind of things are on the table displayed on the slide?'). They established that hungry participants were more likely to 'see' objects (e.g. plates) that are instrumental in the goal of eating than did non-hungry participants. These effects may be explained by heightened accessibility of eating-related objects. On the other hand, these findings show projection and not increased accessibility or perceptual readines s per se. Perceptual readiness points to the amount of stimulus input that is needed to recognize an object. The more perceptually ready, the less input one needs to recognize an object. In the study done by McClelland and Atkinson (1948), participants received no relevant stimulus input at all (except for the specifically chosen questions that triggered imaginative thoughts of hunger or food-related items). Their measure of projection may reveal perceptual readiness, but it may also reveal other, related, processes (e.g. rumination about current concerns, cf. Klinger, 1975) or a combination of different processes. Indeed, it is a commonly reported fact that castaways or survivors start to fantasize about water and food after a period of extreme deprivation (Read, 1996 Wolf, 1958).

Accordingly, in recent years, several investigators have adapted paradigms from cognitive psychology, such as the Stroop (1953) colour-naming task, to examine effects of manipulated hunger (e.g. after a stringent food deprivation regime) and eating disorders (e.g. anorexia and bulimia nervosa) on information processing of food-relevant stimuli (Channon & Hayward, 1990 Green, McKenna, & de Silva, 1994 Green, Elliman, & Rogers, 1996 Mogg, Bradley, Hyare, & Lee, 1998 Ogden & Greville, 1993 Overduin, Jansen, & Louwerse, 1995 Stewart & Samoluk, 1997). By and large, subjective feelings of hunger and chronic thoughts about food habits and body weight have been shown to produce enhanced attention to food items, relative to control items. These findings are more convincing as to the idea that basic needs and motives are related to responsiveness of action-relevant cues.

The goal of the present research is to extend previous work on effects of primary motives on perception and information processing by scrutinizing the assumed relationship between feelings of thirst and perceptual readiness. In two experiments, we tested whether feelings of thirst (induced by tasting and swallowing salty candies) facilitated the ease with which relevant environmental cues were perceived. In Expt 1, some participants were made to feel thirsty, whereas others were not. Subsequently, we assessed the accessibility of drinking-related items by measuring the speed of responding to these items in a lexical decision task (see Neely, 1991). In the lexical decision task, participants were shown letter strings on a computer screen and were told to press a particular key if they thought the letter string was an existing word, or to press another key if they thought the letter string was a non-word. Some of the words designated drinking-related items. If thirst has the potential to prime drinking-related items, then these items should be more accessible as a result of feeling thirsty. As faster response latencies are indicative of enhanced accessibility of, or perceptual readiness to items related to drinking, it is predicted that participants who were made to feel thirsty will be faster in recognizing these items than those who were nor made to feel thirsty.

A group of 58 undergraduates of various departments and disciplines (41 male, 17 female) participated in the experiment, receiving 5 Dutch Guilders in return. They were randomly assigned to either a thirst condition or one of two no-thirst control conditions.

Experimental task and procedure

As the manipulation of thirst consisted of the consumption of certain types of sweets, on arrival at the laboratory, participants were first interviewed on general health problems and prohibitions against consuming specific foods. Participants who were not allowed to consume certain types of food were excluded from further participation in the experiment. Next, participants were told that the study consisted of several separate tasks for which they expressed their consent.

Individual difference in word recognition speed. First, participants were placed in a cubicle and performed a lexical decision task on a computer. They were presented with 10 words that appeared one by one on a computer screen. Five of these words were existing words and the remaining five were nonsense words. For every word appearing on the screen they were asked to decide as quickly and as accurately as possible whether the word was a teal word or nor. Response latencies were measured in milliseconds (ms) from the onset of the words until participants pressed one of two keys on the PC's keyboard marked 'yes' and no'. The words were presented in random order, and preceded by six practice trials. The average response latency across the five existing words served as a covariate to control for between-participants variance in reaction time. Incorrect ('no') responses across these words were excluded from this measure (2.1% out of all responses).

Manipulation of thirst. Next, the test group of participants was confronted with the 'mouth detection' task. As a cover story, participants were told that we were interested in how well people could detect letters with their tongue under different taste conditions. For this task, participants were provided with three salty sweets. Those used here (made of natural liquorice, gum, starch, gelatine and dextrine) are common in The Netherlands. Each sweet weighs about 3 grams, and comprises an additional amount of 14% salt (product name: Bisal). The sweets were round and flat (like a coin) and had a letter (e.g. T, S) on one of the sides. Participants were asked to indicate which letter was marked on each one by using their tongue. They were given 1 minute to detect each letter and to consume the sweet. We assumed that the combined effects of the salty taste and post-ingestive effects of the salt would increase feelings of thirst, and hence, this condition is referred to as the thirst condition. (1) It is importan t to note, however, that this treatment may have its effects through a number of possible mechanisms. We will return to this point in the discussion section.

We used two control conditions. As a first control condition (Control I) some of the participants were requested to carefully draw three figures. Similar to the thirst condition, participants were given 1 minute to draw each figure. As a second control condition (control II) a group of the participants followed the same procedure as described in the thirst condition, only this time three non-salty sweets were used (similar weight and shape, and also made of natural liquorice, gum, starch, gelatine and dextrine product name: Tosca). This second control condition was used to rule out the possibility that the effects of the thirst condition were caused by the mere act of eating liquorice sweets. Pilot-study. Prior to the experiment we conducted pilot-tests to assess the effects of our treatments on self-reported measures of thirst and hunger. A total of 21 undergraduates (drawn from a different population than in the experiments) were assigned randomly to either the thirst or one of the two control (I and II) c onditions. After 4 minutes, they responded to two items assessing the degree of thirst ('How thirsty do you feel right now?') and hunger (How hungry do you feel right now?'). Unipolar 10-point answer scales ranging from 'not at all' (1) to very much' (10) accompanied both items. An ANOVA revealed a significant effect of the treatment on ratings of thirst, F(2, 18) = 4.72, p < .03, but no effect on ratings of hunger, F(2, 18) = 1.14, n.s. Contrast analyses showed that participants in the thirst condition (M = 7.86) experienced substantially more thirst than in the control I condition (M = 3.86), F(1, 18) = 8.30,p < .01. Furthermore, the difference between the thirst and the control II condition (M = 4.57) was also significant, F(1, 18) = 5.60,p < .03. There was no reliable difference between the two control conditions, F < 1. Thus, the test sweet plus salt treatment increased rated thirst over 1 minute post-ingestion.

Word recognition speed of drinking-related items. Immediately after participants had been exposed to the experimental conditions, they were given a second lexical decision task. For this task participants responded to 48 words (different from those in the first task), 24 of which were existing words and 24 were nonsense words. The words were presented in random order, and were preceded by six practice trials. Among the existing words were eight words designated drinking-related items (glass, bottle, can, beaker, cup, water, soda, juice). (2) The other 16 words designated furniture and interior items, and these words were presumed not to be associated with thirst and drinking (e.g. chair, table and lamp). The length of the type of words was controlled for. That is, the mean length of the drinking-related items and the non-drinking related items was equal (M = 5.3 letters). The drinking-related items were selected on the basis of a pre-rest, in which 36 students indicated how strongly they associate several ite ms with thirst and drinking on a 9-point scale that ranged from 'not at all' (1) to 'extremely strong' (9). The average association strength of the eight selected items was 6.80, and ranged across items from 5.62 to 8.34. Thus, these eight items comprise the experimental target words of the lexical decision task. The other 16 items served as controls.

After the lexical decision task, participants were thoroughly debriefed and paid. The debriefing indicated that participants were unaware of the hypotheses under investigation. None of the participants indicated suspicion as to the actual relationship between the tasks. In fact, most participants simply believed that the research was dealing with the issues stated in the cover story of each task.

Incorrect ('no') responses to existing words were excluded from further analyses (0.8% out of all responses, which were evenly distributed across conditions). The average response latency across the drinking-related words and non-drinking related words served us the dependent variables. The response latencies were subjected to a 3 (Treatment: control I vs. control II vs. thirst) between-participants x2 (Type of item: drinking-related vs. non-drinking related) within participants ANCOVA with the response latencies on the first lexical decision task as a covariate. The analysis revealed a non-significant main effect of Treatment, F(2, 54) = 1.37, n.s. Furthermore, the main effect of Type of item was non-significant, F(2, 54) = 1.75, n.s. However, the interaction between Treatment and Type of item was reliable, F(2, 54) = 3.45,p < .04. This indicates that Treatment evoked differential response latency effects across the two (drinking and non-drinking related) different types of items. The means for each cell in the design are displayed in Table 1.

Separate analyses for drinking and non-drinking related items yielded a significant main effect of Treatment on response latencies of drinking-related items, F(2, 54) = 3.93, p < .02, and a non-significant main effect of Treatment on response latencies of non-drinking related items, F < 1, n.s. In other words, reliable differences between the Treatment conditions emerged for drinking-related items, but not for non-drinking related items. As can be seen in Table 1, participants' response latencies of drinking-related items in the thirst condition were reliably shorter than participants' response latencies in the control I condition, F(l, 54) = 7.14, p < .01. Furthermore, participants in the thirst condition responded faster to the drinking-related items than those in the control II condition, F(1, 54) = 4.25, p < .05, although the difference was smaller. There was no significant difference between the two control conditions, F < 1.

In short, participants who had taken in salty sweets during a mouth-detection skill task responded faster to drinking-related items than did participants who had not been exposed to such salt-intake conditions. These results are consistent with the idea that inducing feelings of thirst (or a desire to drink) significantly heightens the accessibility of drinking-related items.

The aim of Expt 2 was to replicate the results of Expt 1 using a different paradigm in which the items had to be detected in the environment. As in Expt 1, some participants were made to feel thirsty, whereas others were not. Subsequently, the accessibility of drinking-related items was measured using an incidental recall task (Brewer & Treyens, 1981 Conforto & Gershman, 1985 Dijksterhuis, Bargh, & Miedema, 2000), in which participants were asked to wait in another office for 4 minutes. In addition to typical office items, several drinking-related items were placed in this room. Upon returning to the room where the experiment started, participants were asked to recall the items that were present in the office. Although previous studies using this paradigm suggest that participants may have difficulties in retrieving items to which they are previously exposed, the incidental recall task should produce sufficient variance on the number of recalled items to test differences between conditions. Based on the ide a that more accessible information is more likely to be encoded and recalled (Carlston & Smith, 1996 Fiske & Taylor, 1991 Higgins, 1996), we expected feeling of thirst to enhance recollection of drinking-related items, relative to non-drinking related items.

Although the pattern of results in Expt 1 was in line with predictions, closer observation of the data suggests that, overall, there was somewhat more differentiation between the thirst and control I conditions, than between the thirst and control II conditions. That is, differences on self-reported feelings of thirst and response latencies of drinking-related items were smaller between the thirst and control II conditions, than between the thirst and control I conditions. The less pronounced distinction between the thirst and control II conditions may have been caused by the fact that the control II group also had to eat liquorice sweets, which may have increased their feelings of thirst, or the desire to drink too (see Mogg et al., 1998, for a comparable effect on feelings of hunger as a result of different fasting conditions). Therefore, to differentiate more strongly between feelings and non-feelings of thirst, and thus to provide a more sensitive test to investigate effects of thirst on recollection of d rinking-related items in the incidental recall task, only the thirst and control I conditions from Expt 1 were used.

Furthermore, in this second experiment we included a behavioural measure to assess whether our manipulation of thirst indeed made participants feel thirstier. For this additional purpose we observed participants' responses to an invitation to drink a glass of water at the end of the experimental session.

A sample composed of 84 undergraduates of various departments and disciplines (53 male, 31 female) participated in the experiment, each receiving 5 Dutch Guilders in return. They were randomly assigned to either the thirst or control I condition from Expt 1.

Experimental task and procedure

As in Expt 1, participants were first interviewed on general health problems and prohibitions against consuming specific foods. Subsequently, they were told that the study consisted of several separate tasks, and were seated in a room and exposed to the thirst or control I condition. Next, they filled out a short unrelated questionnaire (which took 1 minute) in another room that was described as the office of the experimenter. Participants were seated at a table facing the experimenter's desk containing a PC and typical office items (e.g. books, pencils). Additionally, eight drinking-related objects (e.g. glass, bottle) were placed on the desk. Participants were left alone in the office for 4 minutes. On their return, they were given a surprise free recall task in which they were asked to recall the objects present on the experimenter's desk in the room they had been in previously. The numbers of drinking-related and non-drinking related items correctly recalled were recorded.

After the recall task, participants were offered a glass of water to test whether the thirst condition did enhance the desire to drink. Finally, participants were thoroughly debriefed and paid. The debriefing revealed that participants were nor aware of a possible effect of the mouth detection task on later performance, and that they were unaware of the hypotheses under investigation. However, two participants stated that they had tried to memorize all the items that were present in the other room (including the wallpaper). Hence, these two participants were excluded from further analyses.

To check whether we succeeded in manipulating feelings of thirst we subjected participants' responses to drink (yes or no) to a Chi-squared test. In the thirst condition 34% (15/44) of the participants decided to take a drink, against 16% (6/38) in the control condition, [chi square](1) = 3.69, p < .06.

The mean number of recalled drinking-related items and non-drinking related items for both groups are presented in Table 2. Although the recall measures did not show normal distributions, the pattern of means suggests that participants in the thirst condition were better in recalling the drinking-related items than participants in the control condition, whereas differences between the two conditions did not emerge for the recall of non-drinking related items. In other words, feelings of thirst enhanced the recall of drinking-related items, relative to non-drinking related items. Indeed, the difference score [(number of drinking-related items) - (number of non-drinking related items)] was more positive in the thirst condition (M = -0.14) than in the control condition (M = -0.68), Mann-Whitney U = 659, p < .05 (one-tailed). These results indicate that inducing feelings of thirst enhance the attention to, and recall of, drinking-related items.

The findings from two experiments supported the idea that thirst is capable of priming action-relevant cues. More specifically, the arousal of thirst increased the accessibility of drinking-related items, as was observed by faster responses to drinking-related items in a lexical decision task, and better memory for these items in an incidental recall task. In doing so, we demonstrated that thirst heightens the perceptual readiness of environmental stimuli instrumental in the goal of reducing thirst. The present data thus complement research that focuses on physiological causes of thirst and drinking (see also, Logue, 1991), in showing a possible intermediary route from thirst, via mental accessibility of action-relevant stimuli, to the initiation of drinking behaviour (Dickinson & Balleine, 1994 Gallistel, 1990).

The present results also extend research on the effects of feelings of hunger and eating disorders on selective information processing (Green et a. 1994 Ogden & Greville, 1993 Overduin et al., 1995). The most widely (and successfully) used paradigm in these studies to assess responsiveness to food stimuli is the Stroop colour-naming task (for a review on this task, see McLeod, 1991). In this task, participants are asked to name the colour of food words (e.g. chips printed in blue), and retardation of the responses is believed to provide evidence for selective processing or attentional biases of food words (but see Mogg et a. 1998 for a recent treatment of attentional bias effect of hunger in a probe detection task). More precisely, the colour of food items is named more slowly as the automatic activation of the food items interferes, and hence, requires active suppression (which takes time and thus slows down the colour responses). Like the faster recognition, and superior recall of, drinking-related i tems observed in the present research, the interference of food items in a Stroop task may also be caused by enhanced perceptual readiness to, or mental accessibility of these items. Indeed, there is a growing amount of literature suggesting that accessibility of concepts increases the latencies of colour responses in a Stroop task (Jacoby, McElree, & Trainham, 1999 Johnston, Hudson, & Ward, 1997 Kawakami, Dovidio, Moll, Hermsen, & Russia, 2000 Lane & Wegner, 1995). Clearly, the paradigms available for studying the relation between motivational states and accessibility of action-relevant cues (e.g. lexical decision task, incidental recall task, Stroop task) focus on different aspects of information processing at the time of measurement (e.g. encoding, retrieval, controlling interfering responses). Given this diversity of potential accessibility measures, it would therefore seem useful for future research to examine the extent to which these measures covary and reveal differences in responses under differen t levels of various motivational states. Such an enterprise provides a more complete answer on the question of how accessibility affects cognitive biases for cues associated with the regulation of motives.

Furthermore, the present inquiry into situationally induced feelings of thirst may be relevant to research on differential effects of manipulated and chronic motives on accessibility of action-relevant stimuli. Experimental work on hunger suggests that this matter is rather complicated. For instance, Overduin et al. (1995) employed the Stroop task and established that ingestion of an appetizer evoked cognitive bias for food words in non-restrained eaters, whereas restrained eaters showed chronic cognitive bias. Their data suggest that only non-dieters respond to food manipulations by showing enhanced accessibility of food items. However, Ogden and Greville (1993) found that only (chronically) restrained eaters showed retardation in a Stroop task on food words after a high-calorie preload, suggesting that the consumption of a forbidden food may increase dieters' concern about food and their weight. These findings indicate that situational and chronic motives do not have independent effects on accessibility of action-relevant cues. However, because these results do not provide a clear picture of how this interaction emerges, it still awaits further empirical testing. In this respect, the present analysis points to possible methods that may be helpful in studying the interplay of situationally induced, and more chronic, motivational states of thirst in humans.

Apart from the evidence obtained for increased accessibility of drinking-related items, we established that salt intake during a mouth-detection skill task aroused subjective experiences of thirst (Expt 1) and preferences for drinking (Expt 2). However, it should be noted that we did not measure the physiological changes typically associated with thirst and drinking as a function of our manipulations. Strictly speaking, then, the primary motive of thirst may not necessarily be the cause of the observed pattern of effects. In fact, the amount of salt load used in the thirst condition may have been insufficient to induce physiological thirst in humans. Therefore, this treatment may have produced the observed effects through a number of other possible mechanisms. For instance, it may be that the manipulation in the thirst condition left an unpleasant salty taste in participants' mouths as the salt stimulated their tongues, and this was the motivation (e.g. need to rinse) behind the enhanced accessibility of drin king-related items. Moreover, on an even more fundamental level, the oral and pharyngeal recognition of the chemical structure of the salt might have been sufficient to produce a need for fluid (cf. Poothullil, 1995), and hence, subsequent heightened responsiveness to drinking-related cues. However, it should be noted that although these alternatives might account for the present findings, these accounts still support the notion that motivation affects perceptual readiness. On the other hand, in order to provide conclusive evidence on the question of how thirst-inducing stimuli heighten perceptual readiness to environmental cues that are instrumental in reducing thirst, these alternatives point to the need for further experimental scrutiny of cognitive effects of thirst.

In conclusion, the present research aimed to shed light on one of the mental processes that mediate the relationship between basic motives -- such as thirst -- and behaviour. Evidently, if we get thirsty enough -- say, after walking around for many hours on a hot day without any water -- the wish to drink will be predominant in our minds (the concept of full activation see Wegner & Smart, 1997). Such conditions produce an intentional search in the environment to quench the excessive thirst. In normal daily life, however, we rarely put ourselves in the situation of experiencing such extreme dehydration. However, animals (or, expressed in more detailed physiology, their body and cells) inconspicuously lose fluid all the time, and are often confronted with oral stimulation increasing their desire to drink. Judged by the timing of their drinks, animals exhibit a capacity to anticipate a less extreme need for fluid (Rolls & Rolls, 1982 Toates, 1979). The mechanism of perceptual readiness may help to 'recognise' instrumental stimuli. Our cognitive system informs us about the conditions of the internal and external environment. It can foster the reduction of thirst by helping us to detect a can of coke or a cool glass of beer that would go unnoticed under other circumstances.

The authors would like to thank Elizabeth Gaffan, Frederick Toates and several anonymous reviewers for their helpful comments on earlier versions of this paper. They are also grateful to Leis Toebes and Gerhard Wildenbeest for their help in setting up the experiments.

(*.) Requests for reprints should be addressed to Henk Aarts, Leiden University, Department of Social and Organizational Psychology, PO BOX 9555, 2300 RB Leiden, The Netherlands (e-mail: [email protected]).

(1.) Because salt-injections (even in small doses) and water deprivation both raise practical and ethical problems (e.g. Winer, 1971), we deemed it more appropriate to follow this alternative method of making participants feel thirsty.

(2.) Of course, in the lexical decision task, Dutch words were used. Here, we report the English translations of the original words.

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What We Know About Leptin

Of the two hormones, leptin -- the appetite suppressor -- appears to be the bigger player in our bodies' energy balance. Some researchers think that leptin helps regulate ghrelin.

Leptin helps signal the brain that the body has enough energy stores such as body fat. But many obese people don't respond to leptin's signals even though they have higher levels of leptin.

In general, the more fat you have, the more leptin is in your blood. But the level varies depending on many factors, including when you last ate and your sleep patterns.

A study showed that rats that were given doses of leptin ended up eating less, but this effect lasted only about two weeks. It seems that the rats developed a resistance to leptin's appetite-cutting effects.


What We Know About Leptin

Of the two hormones, leptin -- the appetite suppressor -- appears to be the bigger player in our bodies' energy balance. Some researchers think that leptin helps regulate ghrelin.

Leptin helps signal the brain that the body has enough energy stores such as body fat. But many obese people don't respond to leptin's signals even though they have higher levels of leptin.

In general, the more fat you have, the more leptin is in your blood. But the level varies depending on many factors, including when you last ate and your sleep patterns.

A study showed that rats that were given doses of leptin ended up eating less, but this effect lasted only about two weeks. It seems that the rats developed a resistance to leptin's appetite-cutting effects.


On the psychology of drinking: Being thirsty and perceptually ready.

The concept of motivation is central to the understanding of why animals, humans included, initiate, select, and persist in specific actions. Researchers from various branches in psychology have examined the motives that instigate us to attend to, and interact with, our external environment (Bindra, 1974 Geen, 1995 Toates, 1986 Young, 1961). It is known that physical and social needs or motives point us to specified incentive stimuli (e.g. water, money, friends), and, as one possible criterion, it is the effort to explore these stimuli that qualifies the behaviour as motivational. For instance, the way we act on the primary motive of thirst nicely exemplifies the fundamental role of motivation in affecting the direction of subsequent behaviour. Out of several possible responses and stimuli that we have at our disposal, for example, we take a glass of water to quench our thirst.

In order to learn more about basic processes underlying the initiation of motivated human action, thirst and behaviour aimed at reducing thirst have been given much empirical attention (Fitzimons, 1972 Logue, 1991 Rolls & Rolls, 1982). Research aimed at understanding thirst itself has been largely concerned with the associated physiological changes. Cannon (1932), for instance, assumed that 'local body signs' play a role in thirst. Cannon conducted experiments on himself and observed an association between the sensation of a dry mouth and the experience of thirst. However, later research showed that a dry mouth is not normally the primary stimulus for thirst. Thus, wetting the mouth does not by itself reduce thirst (Bellows, 1939). Instead, thirst is also produced by general (instead of local) dehydration. That is, intracellular dehydration (e.g. caused by salt-intake), in which body fluid is lost from the cells, leads to thirst. Also, extracellular dehydration (e.g. due to loss of blood), in which fluid is lost from the compartments outside the cells, triggers thirst (Gilman, 1937 Stricker, 1966). Dehydration excites a complex pattern of neural activity in the hypothalamus and higher regions in the cortex (Grossman, 1979 Stellar, 1990) which in turn, lead to drinking and, in humans, reported thirst.

While the work alluded to above sheds light on the importance of physiological events (and mediating neural substrates) causing thirst and drinking, our present focus is on the psychology of thirst. We can all witness that thirst -- defined in terms of physiological changes -- results in behavioural changes such as drinking. The onset of drinking behaviour may result from various motivational and cognitive processes that can elicit these actions. Our goal here was to investigate whether inducing feelings of thirst increased cognitive accessibility of drinking-related cues.

The hypothesis that feelings of thirst leads to heightened accessibility of cues related to drinking is based on the following considerations. We assume that frequent and habitual implementation of a particular behavioural choice (e.g. taking a glass of water, drinking a bottle or can of soda) in order to regulate (the physiological changes that typify thirst increases the strength of the association between these two elements. Once these associations have been developed, thirst can prime action-relevant stimuli, thereby increasing their availability as cues (cf. also Gallistel, 1990). That is, due to instrumental learning, thirst is able to enhance the cognitive accessibility of items (e.g. glass, bottle, and water) that are instrumental in the course of reducing the desire to drink. In a recent review of learning research on the role of internal and external factors in ingestive behaviour Mook (1996) argued that '. hunger and thirst enhance, or, as we say, potentiate, the responses to relevant stimuli. The more potentiation from inside, the less effective the external stimulus has to be to trigger ingestion' (p. 91). Thirst, then, is expected to lead to perceptual readiness (cf. Bruner, 1957) aimed at reducing this thirst.

The idea that thirst causes internal representations of instrumental stimuli to become more accessible is consistent with contemporary animal learning research on the relationship between motives and action (Bolles, 1972 Colwill & Rescola, 1986 Dickinson & Balleine, 1994). Studies with hungry and thirsty rats, for instance, suggest that after a period of training the performance of instrumental actions is mediated by knowledge of the contingency between the action (e.g. pressing a lever) and the outcome or goal (e.g. getting water). Goal-directed actions are thus said to correspond to internal representations of performing that action. Hence, the arousal of primary needs may prime these representations in the service of satisfying the needs.

Although there is no hard evidence pointing to the conclusion that thirst leads to perceptual readiness aimed at reducing this thirst, there is some earlier evidence suggesting that primary motives (such as hunger) are capable of affecting human perception. In a test of the projective expression of needs, McClelland and Atkinson (1948) demonstrated that 16 hours of food deprivation activate eating-related thoughts. These researchers used an ostensibly subliminal perception task (they actually projected empty slides on a screen), and asked participants specific questions about the slides (e.g., 'What kind of things are on the table displayed on the slide?'). They established that hungry participants were more likely to 'see' objects (e.g. plates) that are instrumental in the goal of eating than did non-hungry participants. These effects may be explained by heightened accessibility of eating-related objects. On the other hand, these findings show projection and not increased accessibility or perceptual readines s per se. Perceptual readiness points to the amount of stimulus input that is needed to recognize an object. The more perceptually ready, the less input one needs to recognize an object. In the study done by McClelland and Atkinson (1948), participants received no relevant stimulus input at all (except for the specifically chosen questions that triggered imaginative thoughts of hunger or food-related items). Their measure of projection may reveal perceptual readiness, but it may also reveal other, related, processes (e.g. rumination about current concerns, cf. Klinger, 1975) or a combination of different processes. Indeed, it is a commonly reported fact that castaways or survivors start to fantasize about water and food after a period of extreme deprivation (Read, 1996 Wolf, 1958).

Accordingly, in recent years, several investigators have adapted paradigms from cognitive psychology, such as the Stroop (1953) colour-naming task, to examine effects of manipulated hunger (e.g. after a stringent food deprivation regime) and eating disorders (e.g. anorexia and bulimia nervosa) on information processing of food-relevant stimuli (Channon & Hayward, 1990 Green, McKenna, & de Silva, 1994 Green, Elliman, & Rogers, 1996 Mogg, Bradley, Hyare, & Lee, 1998 Ogden & Greville, 1993 Overduin, Jansen, & Louwerse, 1995 Stewart & Samoluk, 1997). By and large, subjective feelings of hunger and chronic thoughts about food habits and body weight have been shown to produce enhanced attention to food items, relative to control items. These findings are more convincing as to the idea that basic needs and motives are related to responsiveness of action-relevant cues.

The goal of the present research is to extend previous work on effects of primary motives on perception and information processing by scrutinizing the assumed relationship between feelings of thirst and perceptual readiness. In two experiments, we tested whether feelings of thirst (induced by tasting and swallowing salty candies) facilitated the ease with which relevant environmental cues were perceived. In Expt 1, some participants were made to feel thirsty, whereas others were not. Subsequently, we assessed the accessibility of drinking-related items by measuring the speed of responding to these items in a lexical decision task (see Neely, 1991). In the lexical decision task, participants were shown letter strings on a computer screen and were told to press a particular key if they thought the letter string was an existing word, or to press another key if they thought the letter string was a non-word. Some of the words designated drinking-related items. If thirst has the potential to prime drinking-related items, then these items should be more accessible as a result of feeling thirsty. As faster response latencies are indicative of enhanced accessibility of, or perceptual readiness to items related to drinking, it is predicted that participants who were made to feel thirsty will be faster in recognizing these items than those who were nor made to feel thirsty.

A group of 58 undergraduates of various departments and disciplines (41 male, 17 female) participated in the experiment, receiving 5 Dutch Guilders in return. They were randomly assigned to either a thirst condition or one of two no-thirst control conditions.

Experimental task and procedure

As the manipulation of thirst consisted of the consumption of certain types of sweets, on arrival at the laboratory, participants were first interviewed on general health problems and prohibitions against consuming specific foods. Participants who were not allowed to consume certain types of food were excluded from further participation in the experiment. Next, participants were told that the study consisted of several separate tasks for which they expressed their consent.

Individual difference in word recognition speed. First, participants were placed in a cubicle and performed a lexical decision task on a computer. They were presented with 10 words that appeared one by one on a computer screen. Five of these words were existing words and the remaining five were nonsense words. For every word appearing on the screen they were asked to decide as quickly and as accurately as possible whether the word was a teal word or nor. Response latencies were measured in milliseconds (ms) from the onset of the words until participants pressed one of two keys on the PC's keyboard marked 'yes' and no'. The words were presented in random order, and preceded by six practice trials. The average response latency across the five existing words served as a covariate to control for between-participants variance in reaction time. Incorrect ('no') responses across these words were excluded from this measure (2.1% out of all responses).

Manipulation of thirst. Next, the test group of participants was confronted with the 'mouth detection' task. As a cover story, participants were told that we were interested in how well people could detect letters with their tongue under different taste conditions. For this task, participants were provided with three salty sweets. Those used here (made of natural liquorice, gum, starch, gelatine and dextrine) are common in The Netherlands. Each sweet weighs about 3 grams, and comprises an additional amount of 14% salt (product name: Bisal). The sweets were round and flat (like a coin) and had a letter (e.g. T, S) on one of the sides. Participants were asked to indicate which letter was marked on each one by using their tongue. They were given 1 minute to detect each letter and to consume the sweet. We assumed that the combined effects of the salty taste and post-ingestive effects of the salt would increase feelings of thirst, and hence, this condition is referred to as the thirst condition. (1) It is importan t to note, however, that this treatment may have its effects through a number of possible mechanisms. We will return to this point in the discussion section.

We used two control conditions. As a first control condition (Control I) some of the participants were requested to carefully draw three figures. Similar to the thirst condition, participants were given 1 minute to draw each figure. As a second control condition (control II) a group of the participants followed the same procedure as described in the thirst condition, only this time three non-salty sweets were used (similar weight and shape, and also made of natural liquorice, gum, starch, gelatine and dextrine product name: Tosca). This second control condition was used to rule out the possibility that the effects of the thirst condition were caused by the mere act of eating liquorice sweets. Pilot-study. Prior to the experiment we conducted pilot-tests to assess the effects of our treatments on self-reported measures of thirst and hunger. A total of 21 undergraduates (drawn from a different population than in the experiments) were assigned randomly to either the thirst or one of the two control (I and II) c onditions. After 4 minutes, they responded to two items assessing the degree of thirst ('How thirsty do you feel right now?') and hunger (How hungry do you feel right now?'). Unipolar 10-point answer scales ranging from 'not at all' (1) to very much' (10) accompanied both items. An ANOVA revealed a significant effect of the treatment on ratings of thirst, F(2, 18) = 4.72, p < .03, but no effect on ratings of hunger, F(2, 18) = 1.14, n.s. Contrast analyses showed that participants in the thirst condition (M = 7.86) experienced substantially more thirst than in the control I condition (M = 3.86), F(1, 18) = 8.30,p < .01. Furthermore, the difference between the thirst and the control II condition (M = 4.57) was also significant, F(1, 18) = 5.60,p < .03. There was no reliable difference between the two control conditions, F < 1. Thus, the test sweet plus salt treatment increased rated thirst over 1 minute post-ingestion.

Word recognition speed of drinking-related items. Immediately after participants had been exposed to the experimental conditions, they were given a second lexical decision task. For this task participants responded to 48 words (different from those in the first task), 24 of which were existing words and 24 were nonsense words. The words were presented in random order, and were preceded by six practice trials. Among the existing words were eight words designated drinking-related items (glass, bottle, can, beaker, cup, water, soda, juice). (2) The other 16 words designated furniture and interior items, and these words were presumed not to be associated with thirst and drinking (e.g. chair, table and lamp). The length of the type of words was controlled for. That is, the mean length of the drinking-related items and the non-drinking related items was equal (M = 5.3 letters). The drinking-related items were selected on the basis of a pre-rest, in which 36 students indicated how strongly they associate several ite ms with thirst and drinking on a 9-point scale that ranged from 'not at all' (1) to 'extremely strong' (9). The average association strength of the eight selected items was 6.80, and ranged across items from 5.62 to 8.34. Thus, these eight items comprise the experimental target words of the lexical decision task. The other 16 items served as controls.

After the lexical decision task, participants were thoroughly debriefed and paid. The debriefing indicated that participants were unaware of the hypotheses under investigation. None of the participants indicated suspicion as to the actual relationship between the tasks. In fact, most participants simply believed that the research was dealing with the issues stated in the cover story of each task.

Incorrect ('no') responses to existing words were excluded from further analyses (0.8% out of all responses, which were evenly distributed across conditions). The average response latency across the drinking-related words and non-drinking related words served us the dependent variables. The response latencies were subjected to a 3 (Treatment: control I vs. control II vs. thirst) between-participants x2 (Type of item: drinking-related vs. non-drinking related) within participants ANCOVA with the response latencies on the first lexical decision task as a covariate. The analysis revealed a non-significant main effect of Treatment, F(2, 54) = 1.37, n.s. Furthermore, the main effect of Type of item was non-significant, F(2, 54) = 1.75, n.s. However, the interaction between Treatment and Type of item was reliable, F(2, 54) = 3.45,p < .04. This indicates that Treatment evoked differential response latency effects across the two (drinking and non-drinking related) different types of items. The means for each cell in the design are displayed in Table 1.

Separate analyses for drinking and non-drinking related items yielded a significant main effect of Treatment on response latencies of drinking-related items, F(2, 54) = 3.93, p < .02, and a non-significant main effect of Treatment on response latencies of non-drinking related items, F < 1, n.s. In other words, reliable differences between the Treatment conditions emerged for drinking-related items, but not for non-drinking related items. As can be seen in Table 1, participants' response latencies of drinking-related items in the thirst condition were reliably shorter than participants' response latencies in the control I condition, F(l, 54) = 7.14, p < .01. Furthermore, participants in the thirst condition responded faster to the drinking-related items than those in the control II condition, F(1, 54) = 4.25, p < .05, although the difference was smaller. There was no significant difference between the two control conditions, F < 1.

In short, participants who had taken in salty sweets during a mouth-detection skill task responded faster to drinking-related items than did participants who had not been exposed to such salt-intake conditions. These results are consistent with the idea that inducing feelings of thirst (or a desire to drink) significantly heightens the accessibility of drinking-related items.

The aim of Expt 2 was to replicate the results of Expt 1 using a different paradigm in which the items had to be detected in the environment. As in Expt 1, some participants were made to feel thirsty, whereas others were not. Subsequently, the accessibility of drinking-related items was measured using an incidental recall task (Brewer & Treyens, 1981 Conforto & Gershman, 1985 Dijksterhuis, Bargh, & Miedema, 2000), in which participants were asked to wait in another office for 4 minutes. In addition to typical office items, several drinking-related items were placed in this room. Upon returning to the room where the experiment started, participants were asked to recall the items that were present in the office. Although previous studies using this paradigm suggest that participants may have difficulties in retrieving items to which they are previously exposed, the incidental recall task should produce sufficient variance on the number of recalled items to test differences between conditions. Based on the ide a that more accessible information is more likely to be encoded and recalled (Carlston & Smith, 1996 Fiske & Taylor, 1991 Higgins, 1996), we expected feeling of thirst to enhance recollection of drinking-related items, relative to non-drinking related items.

Although the pattern of results in Expt 1 was in line with predictions, closer observation of the data suggests that, overall, there was somewhat more differentiation between the thirst and control I conditions, than between the thirst and control II conditions. That is, differences on self-reported feelings of thirst and response latencies of drinking-related items were smaller between the thirst and control II conditions, than between the thirst and control I conditions. The less pronounced distinction between the thirst and control II conditions may have been caused by the fact that the control II group also had to eat liquorice sweets, which may have increased their feelings of thirst, or the desire to drink too (see Mogg et al., 1998, for a comparable effect on feelings of hunger as a result of different fasting conditions). Therefore, to differentiate more strongly between feelings and non-feelings of thirst, and thus to provide a more sensitive test to investigate effects of thirst on recollection of d rinking-related items in the incidental recall task, only the thirst and control I conditions from Expt 1 were used.

Furthermore, in this second experiment we included a behavioural measure to assess whether our manipulation of thirst indeed made participants feel thirstier. For this additional purpose we observed participants' responses to an invitation to drink a glass of water at the end of the experimental session.

A sample composed of 84 undergraduates of various departments and disciplines (53 male, 31 female) participated in the experiment, each receiving 5 Dutch Guilders in return. They were randomly assigned to either the thirst or control I condition from Expt 1.

Experimental task and procedure

As in Expt 1, participants were first interviewed on general health problems and prohibitions against consuming specific foods. Subsequently, they were told that the study consisted of several separate tasks, and were seated in a room and exposed to the thirst or control I condition. Next, they filled out a short unrelated questionnaire (which took 1 minute) in another room that was described as the office of the experimenter. Participants were seated at a table facing the experimenter's desk containing a PC and typical office items (e.g. books, pencils). Additionally, eight drinking-related objects (e.g. glass, bottle) were placed on the desk. Participants were left alone in the office for 4 minutes. On their return, they were given a surprise free recall task in which they were asked to recall the objects present on the experimenter's desk in the room they had been in previously. The numbers of drinking-related and non-drinking related items correctly recalled were recorded.

After the recall task, participants were offered a glass of water to test whether the thirst condition did enhance the desire to drink. Finally, participants were thoroughly debriefed and paid. The debriefing revealed that participants were nor aware of a possible effect of the mouth detection task on later performance, and that they were unaware of the hypotheses under investigation. However, two participants stated that they had tried to memorize all the items that were present in the other room (including the wallpaper). Hence, these two participants were excluded from further analyses.

To check whether we succeeded in manipulating feelings of thirst we subjected participants' responses to drink (yes or no) to a Chi-squared test. In the thirst condition 34% (15/44) of the participants decided to take a drink, against 16% (6/38) in the control condition, [chi square](1) = 3.69, p < .06.

The mean number of recalled drinking-related items and non-drinking related items for both groups are presented in Table 2. Although the recall measures did not show normal distributions, the pattern of means suggests that participants in the thirst condition were better in recalling the drinking-related items than participants in the control condition, whereas differences between the two conditions did not emerge for the recall of non-drinking related items. In other words, feelings of thirst enhanced the recall of drinking-related items, relative to non-drinking related items. Indeed, the difference score [(number of drinking-related items) - (number of non-drinking related items)] was more positive in the thirst condition (M = -0.14) than in the control condition (M = -0.68), Mann-Whitney U = 659, p < .05 (one-tailed). These results indicate that inducing feelings of thirst enhance the attention to, and recall of, drinking-related items.

The findings from two experiments supported the idea that thirst is capable of priming action-relevant cues. More specifically, the arousal of thirst increased the accessibility of drinking-related items, as was observed by faster responses to drinking-related items in a lexical decision task, and better memory for these items in an incidental recall task. In doing so, we demonstrated that thirst heightens the perceptual readiness of environmental stimuli instrumental in the goal of reducing thirst. The present data thus complement research that focuses on physiological causes of thirst and drinking (see also, Logue, 1991), in showing a possible intermediary route from thirst, via mental accessibility of action-relevant stimuli, to the initiation of drinking behaviour (Dickinson & Balleine, 1994 Gallistel, 1990).

The present results also extend research on the effects of feelings of hunger and eating disorders on selective information processing (Green et a. 1994 Ogden & Greville, 1993 Overduin et al., 1995). The most widely (and successfully) used paradigm in these studies to assess responsiveness to food stimuli is the Stroop colour-naming task (for a review on this task, see McLeod, 1991). In this task, participants are asked to name the colour of food words (e.g. chips printed in blue), and retardation of the responses is believed to provide evidence for selective processing or attentional biases of food words (but see Mogg et a. 1998 for a recent treatment of attentional bias effect of hunger in a probe detection task). More precisely, the colour of food items is named more slowly as the automatic activation of the food items interferes, and hence, requires active suppression (which takes time and thus slows down the colour responses). Like the faster recognition, and superior recall of, drinking-related i tems observed in the present research, the interference of food items in a Stroop task may also be caused by enhanced perceptual readiness to, or mental accessibility of these items. Indeed, there is a growing amount of literature suggesting that accessibility of concepts increases the latencies of colour responses in a Stroop task (Jacoby, McElree, & Trainham, 1999 Johnston, Hudson, & Ward, 1997 Kawakami, Dovidio, Moll, Hermsen, & Russia, 2000 Lane & Wegner, 1995). Clearly, the paradigms available for studying the relation between motivational states and accessibility of action-relevant cues (e.g. lexical decision task, incidental recall task, Stroop task) focus on different aspects of information processing at the time of measurement (e.g. encoding, retrieval, controlling interfering responses). Given this diversity of potential accessibility measures, it would therefore seem useful for future research to examine the extent to which these measures covary and reveal differences in responses under differen t levels of various motivational states. Such an enterprise provides a more complete answer on the question of how accessibility affects cognitive biases for cues associated with the regulation of motives.

Furthermore, the present inquiry into situationally induced feelings of thirst may be relevant to research on differential effects of manipulated and chronic motives on accessibility of action-relevant stimuli. Experimental work on hunger suggests that this matter is rather complicated. For instance, Overduin et al. (1995) employed the Stroop task and established that ingestion of an appetizer evoked cognitive bias for food words in non-restrained eaters, whereas restrained eaters showed chronic cognitive bias. Their data suggest that only non-dieters respond to food manipulations by showing enhanced accessibility of food items. However, Ogden and Greville (1993) found that only (chronically) restrained eaters showed retardation in a Stroop task on food words after a high-calorie preload, suggesting that the consumption of a forbidden food may increase dieters' concern about food and their weight. These findings indicate that situational and chronic motives do not have independent effects on accessibility of action-relevant cues. However, because these results do not provide a clear picture of how this interaction emerges, it still awaits further empirical testing. In this respect, the present analysis points to possible methods that may be helpful in studying the interplay of situationally induced, and more chronic, motivational states of thirst in humans.

Apart from the evidence obtained for increased accessibility of drinking-related items, we established that salt intake during a mouth-detection skill task aroused subjective experiences of thirst (Expt 1) and preferences for drinking (Expt 2). However, it should be noted that we did not measure the physiological changes typically associated with thirst and drinking as a function of our manipulations. Strictly speaking, then, the primary motive of thirst may not necessarily be the cause of the observed pattern of effects. In fact, the amount of salt load used in the thirst condition may have been insufficient to induce physiological thirst in humans. Therefore, this treatment may have produced the observed effects through a number of other possible mechanisms. For instance, it may be that the manipulation in the thirst condition left an unpleasant salty taste in participants' mouths as the salt stimulated their tongues, and this was the motivation (e.g. need to rinse) behind the enhanced accessibility of drin king-related items. Moreover, on an even more fundamental level, the oral and pharyngeal recognition of the chemical structure of the salt might have been sufficient to produce a need for fluid (cf. Poothullil, 1995), and hence, subsequent heightened responsiveness to drinking-related cues. However, it should be noted that although these alternatives might account for the present findings, these accounts still support the notion that motivation affects perceptual readiness. On the other hand, in order to provide conclusive evidence on the question of how thirst-inducing stimuli heighten perceptual readiness to environmental cues that are instrumental in reducing thirst, these alternatives point to the need for further experimental scrutiny of cognitive effects of thirst.

In conclusion, the present research aimed to shed light on one of the mental processes that mediate the relationship between basic motives -- such as thirst -- and behaviour. Evidently, if we get thirsty enough -- say, after walking around for many hours on a hot day without any water -- the wish to drink will be predominant in our minds (the concept of full activation see Wegner & Smart, 1997). Such conditions produce an intentional search in the environment to quench the excessive thirst. In normal daily life, however, we rarely put ourselves in the situation of experiencing such extreme dehydration. However, animals (or, expressed in more detailed physiology, their body and cells) inconspicuously lose fluid all the time, and are often confronted with oral stimulation increasing their desire to drink. Judged by the timing of their drinks, animals exhibit a capacity to anticipate a less extreme need for fluid (Rolls & Rolls, 1982 Toates, 1979). The mechanism of perceptual readiness may help to 'recognise' instrumental stimuli. Our cognitive system informs us about the conditions of the internal and external environment. It can foster the reduction of thirst by helping us to detect a can of coke or a cool glass of beer that would go unnoticed under other circumstances.

The authors would like to thank Elizabeth Gaffan, Frederick Toates and several anonymous reviewers for their helpful comments on earlier versions of this paper. They are also grateful to Leis Toebes and Gerhard Wildenbeest for their help in setting up the experiments.

(*.) Requests for reprints should be addressed to Henk Aarts, Leiden University, Department of Social and Organizational Psychology, PO BOX 9555, 2300 RB Leiden, The Netherlands (e-mail: [email protected]).

(1.) Because salt-injections (even in small doses) and water deprivation both raise practical and ethical problems (e.g. Winer, 1971), we deemed it more appropriate to follow this alternative method of making participants feel thirsty.

(2.) Of course, in the lexical decision task, Dutch words were used. Here, we report the English translations of the original words.

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Disorders of motivation [ edit | edit source ]

The control of motivation is only understood to a limited extent. There are many different approaches of motivation training, but many of these are considered pseudoscientific by critics. To understand how to control motivation it is first necessary to understand why many people lack motivation.

Employee motivation [ edit | edit source ]

Workers in any organization need something to keep them working. Most of the time, the salary of the employee is enough to keep him or her working for an organization. An employee must be motivated to work for a company or organization. If no motivation is present in an employee, then that employee’s quality of work or all work in general will deteriorate.

When motivating an audience, you can use general motivational strategies or specific motivational appeals. General motivational strategies include soft sell versus hard sell and personality type. Soft sell strategies have logical appeals, emotional appeals, advice and praise. Hard sell strategies have barter, outnumbering, pressure and rank. Also, you can consider basing your strategy on your audience personality. Specific motivational appeals focus on provable facts, feelings, right and wrong, audience rewards and audience threats. Β]

Job Characteristics Model [ edit | edit source ]

The Job Characteristics Model (JCM), as designed by Hackman and Oldham Γ] attempts to use job design to improve employee motivation. They have identified that any job can be described in terms of five key job characteristics

1. Skill Variety - the degree to which a job requires different skills and talents to complete a number of different activities

2. Task Identity - this dimension refers to the completion of a whole and identifiable piece of work versus a partial task as part of a larger piece of work

3. Task Significance - is the impact of the task upon the lives or work of others

4. Autonomy - is the degree of independence or freedom allowed to complete a job

5. Task Feedback - individually obtaining direct and clear feedback about the effectiveness of the individual carrying out the work activities

The JCM links these core job dimensions listed above to critical psychological states which results in desired personal and work outcomes. This forms the basis of this 'employee growth-need strength." The core dimensions listed above can be combined into a single predictive index, called the Motivating Potential Score.

Motivating Potential Score [ edit | edit source ]

The motivating potential score (MPS) can be calculated, using the core dimensions discussed above, as follows

Jobs that are high in motivating potential must be high on at least one of the three factors that lead to experienced meaningfulness, and also must be high on both Autonomy and Feedback. Δ] If a job has a high MPS, the job characteristics model predicts that motivation, performance and job satisfaction will be positively affected and the likelihood of negative outcomes, such as absenteeism and turnover, will be reduced. Δ]

Drugs and motivation [ edit | edit source ]

Some authors, especially in the transhumanist movement, have suggested the use of "smart drugs", also known as nootropics, as "motivation-enhancers". The effects of many of these drugs on the brain are emphatically not well understood, and their legal status often makes open experimentation difficult.

Converging neurobiological evidence also supports the idea that addictive drugs such as cocaine, nicotine, alcohol, and heroin act on brain systems underlying motivation for natural rewards, such as the mesolimbic dopamine system. Normally, these brain systems serve to guide us toward fitness-enhancing rewards (food, water, sex, etc.), but they can be co-opted by repeated use of drugs of abuse, causing addicts to excessively pursue drug rewards. Therefore, drugs can hijack brain systems underlying other motivations, causing the almost singular pursuit of drugs characteristic of addiction.


John B. Watson

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John B. Watson, in full John Broadus Watson, (born January 9, 1878, Travelers Rest, near Greenville, South Carolina, U.S.—died September 25, 1958, New York, New York), American psychologist who codified and publicized behaviourism, an approach to psychology that, in his view, was restricted to the objective, experimental study of the relations between environmental events and human behaviour. Watsonian behaviourism became the dominant psychology in the United States during the 1920s and ’30s.

What was John B. Watson’s childhood like?

John B. Watson grew up in a poor farming family. His father drank heavily, was prone to violence, and was frequently absent he finally left the family when John was 13 years old. By his own account, John was an unruly child and a poor student.

Where was John B. Watson educated?

As a young child, John B. Watson was educated in a one-room schoolhouse and at a modest private academy in Travelers Rest, South Carolina. He entered Furman University in Greenville, South Carolina, when he was 16 and received a master’s degree in 1899. He earned a Ph.D. in psychology at the University of Chicago in 1903.

What did John B. Watson write?

John B. Watson wrote, among other works, Behavior: An Introduction to Comparative Psychology (1914) Psychology from the Standpoint of a Behaviorist (1919), considered the definitive statement of his psychology Behaviorism (1925), a book for the general reader and Psychological Care of Infant and Child (1928).

Why is John B. Watson famous?

John B. Watson is famous for having founded classical behaviourism, an approach to psychology that treated behaviour (both animal and human) as the conditioned response of an organism to environmental stimuli and inner biological processes and that rejected as unscientific all supposed psychological phenomena that were not objectively measurable or observable.

Watson received a Ph.D. in psychology from the University of Chicago (1903), where he then taught. In 1908 he became professor of psychology at Johns Hopkins University and immediately established a laboratory for research in comparative, or animal, psychology. He articulated his first statements on behaviourist psychology in the epoch-making article “Psychology as a Behaviorist Views It” (1913), claiming that psychology is the science of human behaviour, which, like animal behaviour, should be studied under exacting laboratory conditions.

His first major work, Behavior: An Introduction to Comparative Psychology, was published in 1914. In it he argued forcefully for the use of animal subjects in psychological study and described instinct as a series of reflexes activated by heredity. He also promoted conditioned responses as the ideal experimental tool. In 1918 Watson ventured into the relatively unexplored field of infant study. In one of his classic experiments—and one of the most controversial in the history of psychology—he conditioned fear of white rats and other furry objects in “Little Albert,” an orphaned 11-month-old boy.

The definitive statement of Watson’s position appears in another major work, Psychology from the Standpoint of a Behaviorist (1919), in which he sought to extend the principles and methods of comparative psychology to the study of human beings and staunchly advocated the use of conditioning in research. His association with academic psychology ended abruptly. In 1920, in the wake of sensational publicity surrounding his divorce from his first wife, Watson resigned from Johns Hopkins. He entered the advertising business in 1921.

Watson’s book Behaviorism (1925), for the general reader, is credited with interesting many in entering professional psychology. Following Psychological Care of Infant and Child (1928) and his revision (1930) of Behaviorism, Watson devoted himself exclusively to business until his retirement in 1946.

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by John P. Rafferty, Editor.


The Concept of Aggressive Drive: Some Additional Considerations 1

Aggression is a kind of behavior, whose goal is the injury of some person or object. This chapter discusses the concept of aggression including instinct, frustration and learning, the drive concept, and purpose in aggressive behavior. Aggressive actions undoubtedly are sometimes carried out to achieve certain purposes, as the ego formulation maintains, yet, it is also apparent that automatic processes, unaffected by ego controls, also occasionally govern the magnitude of aggression displayed in a given situation. A frustration arouses instigation to aggression, and a thwarting will produce instigations to many different kinds of responses. Several critics have maintained that only certain kinds of frustrations give rise to hostile reactions, but mere deprivations supposedly lead to other consequences, such as frustrations can intensify the strength of the responses following immediately afterward. Animals and humans can be trained to respond nonaggressively to situations that ordinarily produce hostile responses. The physiologically aroused subjects may have acted aggressively and then interpreted their feelings as anger, because of what they had done. Cues in the situation, such as the confederate's aggressive and perhaps unpleasant behavior, could have evoked aggressive responses from the physiologically aroused people. This knowledge, which was perhaps also considerably influenced by the confederate's behavior, could have prevented various nonaggressive actions from appearing.

This paper was written while the author was on a research leave at the University of Oxford under a grant from the National Science Foundation.


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Attention: Definition, Types and Characteristics | Term Paper | Psychology

If we say that a particular individual is not paying attention, we are making a mistake, but if we say that he is not paying attention to what we are saying, it is more appropriate, because that person is certainly paying his attention to something. Attention is closely related to awareness. At this point, we are putting forward some main definitions of the concept of attention.

Generally speaking, the process of concentrating the mind upon a particular activity with a view to achieving a specific subject is called attention:

1. Derived Attention:

A particular stimulus may be repulsive in itself, but it may be found attractive on account of another stimulus. In this case, the attention fixed upon the former stimulus is called derived attention. A student having no interest in science studies it, nevertheless, with full attention because he wants to pass in the examination. In the case of derived attention, it is the derived interest which motivates the individual, not the primary interest.

2. Immediate Attention:

When attention becomes focused upon certain objects without any particular effort on the observer’s part, it is called immediate attention. The root cause of this attention is interest, and our consciousness concentrates upon the object without any effort on our part.

3. Sensory or Concrete Attention:

When the attention focuses upon a stimulus possessing a distinct and palpable form, it is called sensory or concrete attention. For instance, the attention which we fix upon a table, chair, book, tree or any other object.

4. Ideational of Abstract Attention:

The individual’s consciousness focuses itself upon the main stimuli through contemplation or thinking. This kind of attention, called ideational attention, is characterised by thinking. Such thoughts as sympathy, pity, maternal love, attachment, etc., belong to this category because they are thought which can be experienced, but not directly observed. Conceptualization of eternal values and virtues also falls into this category. This kind of attention is primarily abstract.

Term Paper # 2. Types of Attention :

Having become familiar with the various conditions which influence attention, it is desirable to obtain some knowledge about the various kinds of attention.

Psychologists have classified attention in the following manner:

1. Voluntary Attention:

This kind of attention operates or comes into existence when the individual consciously fixes all his energy upon a particular stimulus. For instance, the student concentrates his attention upon the questions likely to be asked in an examination, because he wants to pass test. Voluntary attention may also be called active attention because, in this case, the attention is consciously or voluntarily activated, and focused by the individual. Voluntary attention develops gradually with age and maturity and it develops fully when the individual comes into contact with the environment.

2. Non-Voluntary Attention:

The state in which our attention is drawn towards and focused upon a particular object without our desiring it is called non-voluntary attention. While studying for an examination, the student’s attention is consciously focused upon his books, but his attention will be drawn away if some neighbour plays his radio at full volume. In the same way, attractive and beautiful objects draw a person’s attention without any desire on his part to observe them. Some psychologists have called this kind of attention Spontaneous Attention or Habitual Attention, because it is innate. It can also be considered passive or effortless attention.

3. Unvoluntary Attention:

This kind of attention occurs when a person is forced to attend to something against his wishes. The individual is compelled to pay attention to some stimulus although he wishes to avoid or ignore it. This kind of attention has no spontaneity in it, and consequently the individual has to make an effort to focus his attention. If during a teacher’s lecture some loudspeaker starts blaring, the teacher as well as his students avoid to pay attention to its noise.

Attention makes a very important contribution to the acquisition of fresh experiences. In addition the very nature of attention is such that it subsumes within itself a number of factors, sub-factors and influencing factors.

The following are characteristics of attention:

1. Mental Activity:

The process of focussing attention on any object or aim is performed by the mind, but the activity of the mind requires that the aim of concentrating upon the object or the goal should be clear. In the absence of clarity, the mental process does not become active. If the process is active, it provides a stimulus for attention.

2. Selectiveness of Attention:

Our attention does not focus upon a number of objects simultaneously instead, at any one moment our attention focusses upon one specific object. The object on which our attention focusses itself is selected from among a number of objects, and that object possesses some specific and special feature or interest for us. This explains why, from among a class of 30 or 40 students, the teacher’s attention often directs itself primarily towards the naughty or the extremely dull students.

3. Shifting Nature:

It is the nature of attention that it is unstable or shifting. The individual focusses his attention upon one particular object only with effort, and even then he manages to keep it fixed upon that object for hardly three or four seconds. However, there are notable exceptions to this, specially observable among students preparing for examination or devotees singing religious songs these being situations in which persons concentrate their attention for many hours continuously.

The span of attention, at the moment of its initiation, is quite limited. As soon as the task is completed or when a particular series is completed, attention automatically changes to some other object. Adults can usually concentrate attention upon number of things simultaneously, whereas children focus their attention upon single objects.

Attention is always in such a state that it does not remain fixed upon one object for any length of time. Exhaustions or boredom are also responsible for this fact. When we become exhausted with studying text-books, we change over to novels or stories. The turning of attention from one object or activity to another is called its mobility.

6. Activeness or Alertness:

Attention is made possible because of consciousness, and for this reason it is alert. The activities or goals on which we focus our attention have their existence in our consciousness.

According to Wood worth, “The preparatory set of readiness is the essential response in attending.” This is a profoundly true statement. Our body prepares itself for a particular activity even before the process or activity is initiated. Our body reacts according to attention.”

8. Motor Adjustment:

Whatever the object on which our attention is focussed, our sense organs and motor organs adapt themselves to take part in the activity required. As soon as the students seat themselves in the class, their ears, eyes, necks and their bodily positions adapt themselves with reference to the teacher. As N.L. Munn has put, “The act of attending is characterised by reporter adjustment, postural adjustment, muscle tension and central neural adjustment.”

9. Purposiveness:

It is a universal truth that we focus our attention only upon those objects which satisfy our needs or serve our interests, and that, for the achievement of our goals, we become completely attentive. During examinations, students focus their entire attention on their studies because their interest lies in passing the examination.

10. Inquisitiveness:

Our attention is influenced by mobility and explore for novelty. Woodworth named it as inquisitiveness. It explore for new objects.

11. Three Aspects:

There are three aspects of attention:

The process of attention complete in all these three aspects.

Our mental life is a stream of consciousness. We do not attend to all those incidents facts go on at the same time. We select one out of them. Fechner has rightly said, “Attention represents a selection or singling out of certain aspects of the observable environment to the exclusion of others which may at the time be impinging upon the sense organs.”

The Attention has an important place in our life. In one field of learning and habit formation, we have to go with the process of attention.

Following are the characteristics of attention:

2. Attention has shifting nature.

3. Attention has cognitive, affective and conative aspects.

4. Attention has narrow range.

5. Attention increases of clearness of the stimulus.

6. Attention needs motor adjustment.

How does the concentration of attention take place, and what are the conditions which favour this concentration?

There are two kinds of conditions which influence attention:

1. External Conditions of Attention:

Those conditions affecting attention which are concerned with the environment are called its external conditions. These include the form, colour, shape, etc., of the object.

These conditions are as follows:

Our attention is directed towards an object only when a stimulus arises. Infants focus their attention on books or magazines containing colourful pictures. The focussing of attention depends upon the nature of the stimulus. This concentration will be greater, if the stimulus is more intense, and less if the stimulus is weak.

b. Definite Form:

The focussing of attention is also determined by the form the object possesses. If the object or goal has a definite form, focussing of attention is more effective and intense, where as in the case of an object or purpose with an indeterminate form, focussing of attention is hindered.

It has generally been observed that objects of big size attract our attention more easily than do objects of small size. We are easily attracted by large posters or advertisements hung upon walls. Teachers, too, often make use of maps, models and letters of large size to focus the attention of children upon them more effectively.

Our attention also, usually, focusses itself more easily upon stimuli possessing power of movement. A moving train, a flying aeroplane, or kite falling from the sky easily attracts the child’s attention. The teacher, too, can focus the attention of his students more effectively by using moving films, animated models and cartoons.

Objects which are new to a person’s experience draw his attention towards themselves very powerfully. The huge hoardings giving the message of family planning draw one’s attention quickly, because the design made upon them is a novel pattern. In the same way, in the classroom, the students’ attention will be easily focussed, if the teacher uses new pictures, models maps, etc.

f. Change or Variety:

Whenever there is a change in the stimulus, the change itself draws the observer’s attention towards itself. The sudden bursting out of noise in a quiet and peaceful environment draws one’s attention, and it is only natural for a person to try to find out, at once, the cause of the noise.

g. Mysteriousness:

If two people are carrying on a normal conservation, a third person’s attention is not easily attracted towards them. But, if they begin talking of mysterious things or subjects, the observer’s attention is immediately drawn by the mystery of their conversation. It is thus evident that when an element of mystery enters normal or common place behaviour, attention is directed towards it at once.

h. Condition, State or Situation and Achievements:

Many various kinds of stimuli are found existing in human life, since they arise from the myriad situations and circumstances in which an individual finds himself. As a result, the condition or state of attention will be similar to the condition or state of the stimulus.

Contrast has a very important place in the focussing of attention. Wherever there is a contrast, it strikes us and our attention is drawn towards it. People’s attention is automatically drawn to two persons, if one of them is fair and the other dark, or if one of them is very tall and the other very short.

The focussing of attention is also influenced by the duration of a stimulus. A stimulus continuing for a longer period succeeds in retaining the observer’s attention for a longer time, while, on the other hand, objects providing a stimulus for a shorter time hold the observer’s attention for a shorter period.

When any object is repeatedly observed or a lesson is repeatedly learnt or revised, it attracts attention towards itself. For this reason teachers are always advised to revise the lessons taught in class.

Powerful and intense stimuli attract our attention more powerfully than do weak stimuli. Any bright and strong light or a bright colour attracts our attention more effectively than does a soft light or a light colour.

Those conditions of attention which reside within the individual are referred to as the internal conditions of attention. Among these conditions are—interest, aptitude, meaning, past experience, etc. which help in focussing the attention.

They are described in the following lines:

A person’s attitude towards any object is an indicator of the period for which the person’s attention may be fixed on it. As a general rule, a person’s attention remains fixed for a longer period on those objects towards which he has a favourable and positive attitude.

The focusing of attention also depends upon the aptitude of an individual in certain spheres. If a child has greater aptitude in science than other fields, his attention will focus more readily on science. Individual tend to focus attention more deeply upon activities or field of activity for which they have a greater aptitude.

Every individual has a curiosity to become familiar with any new object or piece of knowledge and in order to satisfy that curiosity, he focusses his attention upon that new object. Curiosity focusses the observer’s attention upon the mysterious element in any new object. Individuals become scientists or philosophers only because of their curiosity drive them to contemplate these fields of knowledge.

Our past experiences are the foundations of our attention. When one lesson has been learnt in the class, the next lesson should be based upon the knowledge imparted by the first lesson. If this principle is neglected, the individual’s attention does not focus itself upon the new lesson being taught.

The individual’s attention focusses more conveniently and quickly upon objects and pieces of knowledge whose meaning or purpose is readily perceived by him. Children who understand scientific subjects easily have no difficulty in focussing their attention on them, as they proceed to relatively more complex chapters and lessons, because they have understood the meaning of the preceding lessons.

Habit is that condition of attention which develops specially from the bodily mechanism and its activity. It is because of habit that our attention focusses upon a particular activity. It is often seen that the cricket players become so habituated to the game that they can often be seen standing by the roadside and listening to cricket commentaries with complete attention and absorption. Their whole attention focusses upon the commentary without any effort.

Every object connected with a goal desired by the individual attracts his attention. During examinations, students fix their attention upon the questions asked by the teacher, because those questions are at the moment, a means to their goal of succeeding in examination.

Our attention also focusses itself upon those objects which either satisfy our needs or help in their satisfaction. It is a normal thing for our attention to be focussed upon food when we are hungry or upon water when thirsty.

Apart from these conditions, instinctive needs, such as hunger, thirst, sex, emotions, philosophy of life, past experiences and interests are also true internal condition of attention.

The extent or limit of the ability of a person to attend to a concentrate on something the length of time during which a reader can concentrate on what he is reading without thinking of anything else, varies with age, physical mental and emotional condition and the nature of material read.

Attention brings an object into consciousness. How many objects can be brought into consciousness at a time, the number of them is called span of attention. We cannot attend more than five to six objects at one time.

In experimental psychology, we measure numerous problems of attention such as fluctuation, distraction, apprehension, division, shifting, etc. Shifting among of attention is called distraction of attention. Distract forces mentally effort to six person a task.

Span of attention reveals that the power to apprehend does not increase with age but the capacity to combine units into more and more complex experiments show that an individual cannot attend to any object continuously for a long time. Interest and intensity also effects attention. Distraction is harmful to the achievement of the work.

Attention has a very important place for teaching learning process. Following points should be taken into consideration for the development of attention.

Attention (consciousness) upon a particular object. When we read a book, we focus our attention upon it fully. This process of concentration of attention has been accepted as a major factor in learning.

Psychologists have defined attention in the following various terms:

“It (attention) is the concentration of consciousness upon one object rather than others”.

“Attention is simply conditioned, so far as it requires for its satisfaction to the fuller cognisance of view of its objects.”

“Attention is a process of getting an object of thought clearly before the mind.”

“From whatever angle we consider from the point to its effects, the cognitive process.”

“Attention is merely conation or striving considered from the point of view of its effect on cognitive process.

Attention is the attributive state of sensory clearness the active selection and emphasis of one component of a complex experience, a sensory adjustment of providing for optimal stimulation of a sense modality, adjustment of the sense organs to facilitate response to a particular stimulus or situation and to inhabit response to extraneous stimuli or situation.

It is evident from the foregoing definitions that attention is always obtained or assured. An individual is always in a state of attention. If we claim that a particular student is not paying attention, what we actually mean is that he is paying attention to something other than the pronouncements of the teacher.

When a number of persons are sitting together discussing a particular subject, there may be some who are not paying attention to the subject under discussion because their attention is centred in their thoughts. “The development of attention is centred almost exclusively around the problem of how to direct the attention to a series of subjects or thought processes which are of enough vital significance to keep one alert.”

Gilliland and Stevens Say:

Sensory organs have an impact upon attention. We often experience that, in the case of each individual student, we focus our attention upon separate experiences. Tests have indicated that, because of one or the other reason, our behaviour does not develop. The state of attention is not always the same. The attention focusses on one object at one moment and then upon another object the next moment. If we have to focus simultaneously on a number of objects, out attention will fluctuate rapidly and become unstable.

Attention is a term which implies certain processes lying at the centre of acquisition of sensory knowledge in the process of experiencing. Attention divides the perceived world before us into a centre and a frame or margin.

Attention is focal consciousness. Morgan told it as marginal consciousness. When our consciousness works for reading or to do any desired activity, it is called our focal consciousness, while table, chair, pen, inkpot, paper etc., are our marginal consciousness. Therefore, attention is a selective mental process. We bring it to consciousness through appropriate stimulus.


Drive theory

In psychology, a drive theory, theory of drives or drive doctrine [1] is a theory that attempts to analyze, classify or define the psychological drives. A drive is an instinctual need that has the power of driving the behaviour of an individual [2] an "excitatory state produced by a homeostatic disturbance". [3]

Drive theory is based on the principle that organisms are born with certain psychological needs and that a negative state of tension is created when these needs are not satisfied. When a need is satisfied, drive is reduced and the organism returns to a state of homeostasis and relaxation. According to the theory, drive tends to increase over time and operates on a feedback control system, much like a thermostat.

In 1943 two psychologists, Clark Hull and Kenneth Spence, had the first interest in this idea of motivation. They knew it was a sense of their motivation, drives, and an explanation of all behavior. After years of research, they created the drive theory. [4] In a study conducted by Hull, two groups of rats were put in a maze, group A was given food after three hours and group B was given food after twenty-two hours. Hull had decided that the rats that were deprived of food longer would be more likely to develop a habit of going down the same path to obtain food. [5]


1 Evolutionary explanations can also examine the historical roots of a feature, trait, or behavior. For example, the human hand is quite similar to the hands of other great apes, and the differences between primates can be traced in the bones of now extinct species linking the current species. In this article, we focus on the functional, not the historical, aspect of evolutionary explanations.

2 Of course, there are transformations. Elderly people are less likely to devote attention to mating effort, and such effort in postmeno-pausal females would no longer have direct reproductive consequences.

Declaration of Conflicting Interests

The authors declared that they had no conflicts of interests with respect to their authorship or the publication of this article.


Contents

Psychoanalysis Edit

Sigmund Freud, who is considered the originator of the modern use of the term, [5] defined libido as "the energy, regarded as a quantitative magnitude. of those instincts which have to do with all that may be comprised under the word 'love'." [6] It is the instinctual energy or force, contained in what Freud called the id, the strictly unconscious structure of the psyche. He also explained that it is analogous to hunger, the will to power, and so on [7] insisting that it is a fundamental instinct that is innate in all humans. [8]

Freud developed the idea of a series of developmental phases in which the libido fixates on different erogenous zones—first in the oral stage (exemplified by an infant's pleasure in nursing), then in the anal stage (exemplified by a toddler's pleasure in controlling his or her bowels), then in the phallic stage, through a latency stage in which the libido is dormant, to its reemergence at puberty in the genital stage. [9] (Karl Abraham would later add subdivisions in both oral and anal stages.) [10]

Freud pointed out that these libidinal drives can conflict with the conventions of civilised behavior, represented in the psyche by the superego. It is this need to conform to society and control the libido that leads to tension and disturbance in the individual, prompting the use of ego defenses to dissipate the psychic energy of these unmet and mostly unconscious needs into other forms. Excessive use of ego defenses results in neurosis. A primary goal of psychoanalysis is to bring the drives of the id into consciousness, allowing them to be met directly and thus reducing the patient's reliance on ego defenses. [11]

Freud viewed libido as passing through a series of developmental stages within the individual. Failure to adequately adapt to the demands of these different stages could result in libidinal energy becoming 'dammed up' or fixated in these stages, producing certain pathological character traits in adulthood. Thus the psychopathologized individual for Freud was an immature individual, and the goal of psychoanalysis was to bring these fixations to conscious awareness so that the libido energy would be freed up and available for conscious use in some sort of constructive sublimation.

Analytical psychology Edit

According to Swiss psychiatrist Carl Gustav Jung, the libido is identified as the totality of psychic energy, not limited to sexual desire. [12] [13] As Jung states in "The Concept of Libido," [14] "[libido] denotes a desire or impulse which is unchecked by any kind of authority, moral or otherwise. Libido is appetite in its natural state. From the genetic point of view it is bodily needs like hunger, thirst, sleep, and sex, and emotional states or affects, which constitute the essence of libido." The Duality (opposition) creates the energy (or libido) of the psyche, which Jung asserts expresses itself only through symbols: "It is the energy that manifests itself in the life process and is perceived subjectively as striving and desire." (Ellenberger, 697) These symbols may manifest as "fantasy-images" in the process of psychoanalysis which embody the contents of the libido, otherwise lacking in any definite form. [15] Desire, conceived generally as a psychic longing, movement, displacement and structuring, manifests itself in definable forms which are apprehended through analysis.

Defined more narrowly, libido also refers to an individual's urge to engage in sexual activity, and its antonym is the force of destruction termed mortido or destrudo. [16]

Endogenous compounds Edit

Libido is governed primarily by activity in the mesolimbic dopamine pathway (ventral tegmental area and nucleus accumbens). [2] Consequently, dopamine and related trace amines (primarily phenethylamine) [17] that modulate dopamine neurotransmission play a critical role in regulating libido. [2]

Other neurotransmitters, neuropeptides, and sex hormones that affect sex drive by modulating activity in or acting upon this pathway include:

    [2] (directly correlated) – and other androgens[18][19][20][21][2] (directly correlated) – and related female sex hormones [22][23][24][25][26][25] (inversely correlated) [27] (directly correlated) [28][29][30] (inversely correlated) [28][31]

Sex hormone levels and the menstrual cycle Edit

A woman's desire for sex is correlated to her menstrual cycle, with many women experiencing a heightened sexual desire in the several days immediately before ovulation, [32] which is her peak fertility period, which normally occurs two days before until two days after the ovulation. [33] This cycle has been associated with changes in a woman's testosterone levels during the menstrual cycle. According to Gabrielle Lichterman, testosterone levels have a direct impact on a woman's interest in sex. According to her, testosterone levels rise gradually from about the 24th day of a woman's menstrual cycle until ovulation on about the 14th day of the next cycle, and during this period the woman's desire for sex increases consistently. The 13th day is generally the day with the highest testosterone levels. In the week following ovulation, the testosterone level is the lowest and as a result women will experience less interest in sex. [18] [ better source needed ]

Also, during the week following ovulation, progesterone levels increase, resulting in a woman experiencing difficulty achieving orgasm. Although the last days of the menstrual cycle are marked by a constant testosterone level, women's libido may get a boost as a result of the thickening of the uterine lining which stimulates nerve endings and makes a woman feel aroused. [34] Also, during these days, estrogen levels decline, resulting in a decrease of natural lubrication.

Although some specialists disagree with this theory, menopause is still considered by the majority a factor that can cause decreased sex desire in women. The levels of estrogen decrease at menopause and this usually causes a lower interest in sex and vaginal dryness which makes intercourse painful. However, the levels of testosterone increase at menopause and this may be why some women may experience a contrary effect of an increased libido. [35]

Psychological and social factors Edit

Certain psychological or social factors can reduce the desire for sex. These factors can include lack of privacy or intimacy, stress or fatigue, distraction or depression. Environmental stress, such as prolonged exposure to elevated sound levels or bright light, can also affect libido. Other causes include experience of sexual abuse, assault, trauma, or neglect, body image issues, and anxiety about engaging in sexual activity. [36]

Individuals with PTSD may find themselves with reduced sexual desire. Struggling to find pleasure, as well as having trust issues, many with PTSD experience feelings of vulnerability, rage and anger, and emotional shutdowns, which have been shown to inhibit sexual desire in those with PTSD. [37] Reduced sex drive may also be present in trauma victims due to issues arising in sexual function. For women, it has been found that treatment can improve sexual function, thus helping restore sexual desire. [38] Depression and libido decline often coincide, with reduced sex drive being one of the symptoms of depression. [39] Those suffering from depression often report the decline in libido to be far reaching and more noticeable than other symptoms. [39] In addition, those with depression often are reluctant to report their reduced sex drive, often normalizing it with cultural/social values, or by the failure of the physician to inquire about it.

Physical factors Edit

Physical factors that can affect libido include endocrine issues such as hypothyroidism, the effect of certain prescription medications (for example flutamide), and the attractiveness and biological fitness of one's partner, among various other lifestyle factors. [40]

In males, the frequency of ejaculations affects the levels of serum testosterone, a hormone which promotes libido. A study of 28 males aged 21–45 found that all but one of them had a peak (145.7% of baseline [117.8%–197.3%]) in serum testosterone on the 7th day of abstinence from ejaculation. [41]

Anemia is a cause of lack of libido in women due to the loss of iron during the period. [42]

Smoking, alcohol abuse, and the use of certain drugs can also lead to a decreased libido. [43] Moreover, specialists suggest that several lifestyle changes such as exercising, quitting smoking, lowering consumption of alcohol or using prescription drugs may help increase one's sexual desire. [44] [45]

Medications Edit

Some people purposefully attempt to decrease their libido through the usage of anaphrodisiacs. [46] Aphrodisiacs, such as dopaminergic psychostimulants, are a class of drugs which can increase libido. On the other hand, a reduced libido is also often iatrogenic and can be caused by many medications, such as hormonal contraception, SSRIs and other antidepressants, antipsychotics, opioids, beta blockers and Isotretinoin

Isotretinoin and many SSRIs can cause a long term decrease in libido and other sexual functions, even after users of those drugs have shown improvement in their depression and have stopped usage. [39] [47] Multiple studies have shown that with the exception of bupropion (Wellbutrin), trazodone (Desyrel) and nefazodone (Serzone), antidepressants generally will lead to lowered libido. [39] SSRIs that typically lead to decreased libido are fluoxetine (Prozac), paroxetine (Paxil), fluvoxamine (Luvox), citalopram (Celexa) and sertraline (Zoloft). [39] There are several ways to try and reap the benefits of the antidepressants while maintaining high enough sex drive levels. Some antidepressant users have tried decreasing their dosage in the hopes of maintaining an adequate sex drive. Results of this are often positive, with both drug effectiveness not reduced and libido preserved. Other users try enrolling in psychotherapy to solve depression-related issues of libido. However, the effectiveness of this therapy is mixed, with lots reporting that it had no or little effect on sexual drive. [39]

Testosterone is one of the hormones controlling libido in human beings. Emerging research [48] is showing that hormonal contraception methods like oral contraceptive pills (which rely on estrogen and progesterone together) are causing low libido in females by elevating levels of sex hormone-binding globulin (SHBG). SHBG binds to sex hormones, including testosterone, rendering them unavailable. Research is showing that even after ending a hormonal contraceptive method, SHBG levels remain elevated and no reliable data exists to predict when this phenomenon will diminish. [49]

Oral contraceptives lower androgen levels in users, and lowered androgen levels generally lead to a decrease in sexual desire. However, usage of oral contraceptives has shown to typically not have a connection with lowered libido in women. [50] Multiple studies have shown that usage of oral contraceptives is associated with either a small increase or decrease in libido, with most users reporting a stable sex drive. [51]

Effects of age Edit

Males reach the peak of their sex drive in their teenage years, while females reach it in their thirties. [52] [53] The surge in testosterone hits the male at puberty resulting in a sudden and extreme sex drive which reaches its peak at age 15–16, then drops slowly over his lifetime. In contrast, a female's libido increases slowly during adolescence and peaks in her mid-thirties. [54] Actual testosterone and estrogen levels that affect a person's sex drive vary considerably.

Some boys and girls will start expressing romantic or sexual interest by age 10–12. The romantic feelings are not necessarily sexual, but are more associated with attraction and desire for another. For boys and girls in their preteen years (ages 11–12), at least 25% report "thinking a lot about sex". [55] By the early teenage years (ages 13–14), however, boys are much more likely to have sexual fantasies than girls. In addition, boys are much more likely to report an interest in sexual intercourse at this age than girls. [55] Masturbation among youth is common, with prevalence among the population generally increasing until the late 20s and early 30s. Boys generally start masturbating earlier, with less than 10% boys masturbating around age 10, around half participating by age 11–12, and over a substantial majority by age 13–14. [55] This is in sharp contrast to girls where virtually none are engaging in masturbation before age 13, and only around 20% by age 13–14. [55]

People in their 60s and early 70s generally retain a healthy sex drive, but this may start to decline in the early to mid-70s. [56] Older adults generally develop a reduced libido due to declining health and environmental or social factors. [56] In contrast to common belief, postmenopausal women often report an increase in sexual desire and an increased willingness to satisfy their partner. [57] Women often report family responsibilities, health, relationship problems, and well-being as inhibitors to their sexual desires. Aging adults often have more positive attitudes towards sex in older age due to being more relaxed about it, freedom from other responsibilities, and increased self-confidence. Those exhibiting negative attitudes generally cite health as one of the main reasons. Stereotypes about aging adults and sexuality often regard seniors as asexual beings, doing them no favors when they try to talk about sexual interest with caregivers and medical professionals. [57] Non-western cultures often follow a narrative of older women having a much lower libido, thus not encouraging any sort of sexual behavior for women. Residence in retirement homes has affects on residents' libidos. In these homes, sex occurs, but it is not encouraged by the staff or other residents. Lack of privacy and resident gender imbalance are the main factors lowering desire. [57] Generally, for older adults, being excited about sex, good health, sexual self-esteem and having a sexually talented partner. [58]

A sexual desire disorder is more common in women than in men, [59] and women tend to exhibit less frequent and less intense sexual desires than men. [60] Erectile dysfunction may happen to the penis because of lack of sexual desire, but these two should not be confused. [61] For example, large recreational doses of amphetamine or methamphetamine can simultaneously cause erectile dysfunction and significantly increase libido. [62] However, men can also experience a decrease in their libido as they age.

The American Medical Association has estimated that several million US women suffer from a female sexual arousal disorder, though arousal is not at all synonymous with desire, so this finding is of limited relevance to the discussion of libido. [42] Some specialists claim that women may experience low libido due to some hormonal abnormalities such as lack of luteinising hormone or androgenic hormones, although these theories are still controversial.