Biomedical subjects

Jeffrey M Brunstrom

Publications and source records attributed to Jeffrey M Brunstrom.

12 recordsLinked to original sources

PubMed2007

Associative learning and the control of human dietary behavior.

Most of our food likes and disliked are learned. Relevant forms of associative learning have been identified in animals. However, observations of the same associative processes are relatively scarce in humans. The first section of this paper outlines reasons why this might be the case. Emphasis is placed on recent research exploring individual differences and the importance or otherwise of hunger and contingency awareness. The second section briefly considers the effect of learning on meal size, and the author revisits the question of how learned associations might come to influence energy intake in humans.

Association Learning↗

PubMed2006

Flavor-nutrient learning in restrained and unrestrained eaters.

After we consume a novel food an association can form between its sensory characteristics (e.g., taste properties) and the effect it has on the body (rewarding). Associations of this kind underpin much of our everyday dietary behavior because they mediate both the affective quality of food (flavor-preference learning) and the amount that we choose to consume (learning satiation). Notwithstanding this fact, very few studies have successfully demonstrated the process of dietary learning in human adults. In addition, based on evidence from related research, we explored whether learning is less likely to occur in individuals who have high scores on a measure of dietary restraint. Female participants (N = 44) consumed two differently flavored desserts. Each was presented three times on separate days. One was formulated with a high-energy content (1882 kJ) and the other with a low-energy content (226 kJ). After training, we found little evidence for learned satiation. However, we did observe flavor-preference learning. Specifically, participants acquired a greater liking and desire-to-eat the dessert flavor that was paired with a higher energy density during training. Further analysis revealed that this effect on liking is qualified by dietary restraint. As predicted, unrestrained eaters demonstrated greater differential responding to the two desserts than did restrained eaters. These data provide further evidence for flavor-nutrient learning in adults and they highlight a hitherto unexplored and potentially important difference between restrained and unrestrained eaters.

Adolescent↗

PubMed2006

Effects of distraction on the development of satiety.

Two experiments explored the hypothesis that distraction causes a reduced sensitivity to the physiological and sensory cues that signal when to terminate a meal. In Experiment 1, eighty-eight females ate five 'Jaffa Cakes' either while distracted by a computer game or while sitting in silence. Analysis of the difference in rated hunger, fullness and desire to eat (pre- to post-intake) revealed that distracted participants experienced smaller changes in their desire to eat and fullness than did non-distracted participants. Experiment 2 assessed whether changes in ratings are attenuated because sensory-specific satiety (or a related process) fails to develop. Using a similar procedure, eighty-four females provided desire to eat, pleasantness and intensity ratings for Jaffa Cakes and for two 'uneaten' foods, both before and at three time-points after consuming five Jaffa Cakes. Non-distracted participants reported a reduction in their desire to eat the eaten food relative to the uneaten food (food-specific satiety), whereas distracted participants maintained a desire to eat all foods. Moreover, this difference between distracted and non-distracted participants was evident 5 and 10 min after the eating episode had terminated. The present findings invite speculation that distraction attenuates the development of sensory-specific satiety, and that this effect persists (at least for a brief period) after the distractor has terminated. More generally, this kind of phenomenon warrants further scrutiny because it holds the potential to contribute towards overeating, either by prolonging an eating episode or by reducing the interval between meals.

Adolescent↗

PubMed2005

Dietary restraint and cognitive performance in children.

Adults who attempt to restrict their dietary intake also tend to perform worse on a range of cognitive tasks. However, the extent to which this finding generalises to children has remained unclear. Following studies involving adults, we asked 44 girls (mean age = 10.1 years) to complete a simple reaction-time task and the Tower of London task. This group was selected from a local community school in the East Midlands (UK). Dietary restraint was measured using a version of the Dutch Eating Behaviour Questionnaire that had been adapted for use by children. Our results indicate that children with high restraint scores have longer reaction times and they also tend to perform worse on the TOL task. Other aspects of our data also suggest the dietary restraint may be correlated negatively with a measure of academic ability. We discuss reasons why restraint and performance might be related causally and we conclude that this issue warrants further scrutiny.

Child↗

PubMed2005

Dietary restraint and US devaluation predict evaluative learning.

Previous research has indicated that flavor-flavor learning is impaired in restrained eaters. In Experiment 1 we sought to extend this finding using a larger sample and a more comprehensive assessment of dietary behavior. Participants (N=90, including 30 current dieters) sampled three novel flavors (CSs), each on 10 separate occasions, in a randomized order. Each flavor was paired with chocolate (US) either 10%, 50%, or 90% of the time. We then assessed liking for the three CSs and asked participants to complete the DEBQ-restraint and TFEQ-disinhibition sub-scales. After these CS-US parings, restrained eaters tended to prefer the 10% paired flavor whereas unrestrained eaters tended to prefer the 90% paired flavor. Differential CS liking was not evident in dieters and it was not predicted by disinhibition. Using a similar methodology, in Experiment 2 (N=76) we assessed evaluative change following picture-sweet pairings. Relative to the other CSs, the restrained eaters reported a greater increase in their liking for the 10% paired CS and the unrestrained eaters reported a greater increase in their liking for the 90% paired CS. We also discovered that evaluative change is related to the level of US devaluation that takes place during conditioning. Evidence that a sweet US can bring about a decrease in liking has not been reported previously. One interpretation is that negative beliefs and attitudes can contaminate the representation of the US during training.

Adult↗

PubMed2005

Everyday dietary behaviour and the relationship between attention and meal size.

Previously, it has been demonstrated that overeating can occur when an individual engages in a cognitive task during a meal. One possibility, therefore, is that task performance can provide a measure of attention to dietary control. To explore this idea we measured performance on an otherwise irrelevant task during a meal. In two experiments, we compared intake and performance across five groups of females; dieters, and four groups of non-dieters, each with contrasting high and low scores on the restraint scale of the Dutch Eating Behaviour Questionnaire and the disinhibition scale of the Three-Factor Eating Questionnaire. Our analysis suggests that a correspondence can exist between task performance and intake (Experiment 1) and this might be influenced by the extent to which foods are regarded as forbidden (Experiment 2). However, aspects of our data are difficult to reconcile with the idea that task performance reflects a simple measure of attention to dietary control. Instead, one possibility is that individuals differ in the way that they choose to allocate attention during a meal. In relation to this idea, we discuss the possibility that some individuals choose to avoid food-related cognition by engaging strategically with other aspects of their cognitive environment.

Adult↗

PubMed2005

Dietary learning in humans: directions for future research.

There is every indication that most of our flavor preferences and dietary behaviors are learned. Despite this, we know very little about the underlying mechanisms. This paper considers reasons why this might be the case. In addition to considering particular methodological issues and the potential relevance of a 'critical developmental period', emphasis is placed on the need to resolve whether learning results from an implicit or an explicit process. Addressing this issue has important implications for the way that studies should be designed. It also leads to one of two diametrically opposite conclusions. Either behavior is governed by a rather rare form of automatic and involuntary associative learning, or otherwise, it should be regarded as non-automatic and subject to attentional and other constraints associated with most other forms of learning in humans. This latter proposition invites speculation that learning might also be governed by more complex representations (beliefs and attitudes) associated with the foods and flavors that are presented in learning studies. More generally, an analysis of this kind is important because it has the potential to explain differences that might underpin particular aberrant eating habits.

Animals↗

PubMed2004

Does dietary learning occur outside awareness?

Several forms of dietary learning have been identified in humans. These include flavor-flavor learning, flavor-postingestive learning (including flavor-caffeine learning), and learned satiety. Generally, learning is thought to occur in the absence of contingency (CS-US) or demand awareness. However, a review of the literature suggests that this conclusion may be premature because measures of awareness lack the rigor that is found in studies of other kinds of human learning. If associations do configure outside awareness then this should be regarded as a rare instance of automatic learning. Conversely, if awareness is important, then successful learning may be governed by an individual's beliefs and predilection to attend to stimulus relationships. For researchers of dietary learning this could be critical because it might explain why learning paradigms have a reputation for being unreliable. Since most food preferences are learned, asking questions about awareness can also tell us something fundamental about everyday dietary control.

Association Learning↗

PubMed2004

Automatic and nonautomatic processes in dietary restraint: further evidence for a commonality between food and drug abstinence.

The deleterious effect of dietary restraint on cognitive performance is now well established. However, recent evidence suggests that this impairment shares characteristics with those found in abstinent drug users. In this study, high (n=21) and low-to-medium restrained eaters (n=41) completed a reaction-time task, once while imagining their favourite food and once while imagining their favourite holiday. Afterwards, these participants ate lunch and then completed a second set of reaction-time measures. Both before and after lunch, ratings of the vividness of the scenarios were similar across groups. Likewise, the groups produced similar ratings of hunger, thirst, and desire to eat. However, as predicted, performance was significantly impaired in restrained eaters, but only while imagining food, and only before lunch. No impairments were observed in the low-to-medium restrained group. This finding provides further evidence that Tiffany's [Psychol. Rev. 97 (1990) 147] model of drug-related urges can be generalised to dietary restraint. The merits of conceptualising dietary restraint in terms of automatic and nonautomatic processes are discussed, together with suggestions for future research.

Adult↗

PubMed2004

Dietary restraint and heightened reactivity to food.

Previously, studies have explored the relationship between dietary behavior and salivary reactivity to food. Despite this, it remains unclear which behaviors are associated with enhanced reactivity. One problem is that measures of behavior have not been compared directly. In particular, it is unclear whether elevated reactivity is associated with measures of dietary restraint or with measures of failed dietary control and a tendency to overeat. To address this problem, we compared the association between salivary reactivity and scores on the subscales of the Three-Factor Eating Questionnaire (restraint, disinhibition, and hunger). Estimates of reactivity were derived from the difference between a baseline saliva measure and a similar measure taken in close proximity to hot pizza. Our second aim was to explore how salivary reactivity changes after a meal. Female participants (N=40) were tested before and after a lunch (cheese sandwiches). All tended to show reactivity to pizza before but not after lunch. No significant differences were associated with the disinhibition or hunger subscales. However, prelunch reactivity was significantly greater in those participants with high scores on the restraint scale. This does not appear to be related to reported levels of hunger before lunch. Rather, it may reveal an intrinsic difference between the reaction of restrained and unrestrained eaters to food.

Adolescent↗

PubMed2003

Spectral pattern, harmonic relations, and the perceptual grouping of low-numbered components.

Mistuning a harmonic increases its salience and produces an exaggerated change in its pitch. The effects on component grouping of spectral pattern, global pitch, and local harmonicity were explored using these phenomena. Stimuli were either harmonic (F0 = 200 Hz) or frequency shifted by 25% of F0. Component 1 or 2 was replaced by one of a set of sinusoidal probes in the same spectral region. Listeners either matched the probe pitch by adjusting the frequency of a pure tone (experiments 1 and 3) or matched the probe loudness by adjusting the level of a tone of identical frequency (experiment 2). Probe positions corresponding to greatest perceptual fusion were estimated from the variations in pitch shift and loudness across frequency. Both measures gave similar estimates. For harmonic stimuli, fusion was greatest at harmonic values. For shifted stimuli, fusion was greatest close to the suboctave (225 Hz) and the frequency (450 Hz) of component 2. The latter value moved downwards to near 433 Hz (2:3 ratio with component 3) when component 1 was removed. Together, these results indicate that the lowest component of a shifted complex is grouped by local harmonicity, whereas the higher components are grouped by common spectral spacing. Global pitch did not influence component grouping.

Cochlear Nerve↗

PubMed2002

Effects of mouth dryness on drinking behavior and beverage acceptability.

In humans, the association between mouth dryness and thirst has been examined in a variety of contexts. Typically, drinking behavior produces a concomitant reduction in unpleasant dry mouth sensations. Evidence is reviewed for a mechanism that influences the termination of drinking behavior by metering this change. Drinking behavior causes a progressive increase in parotid saliva flow. Thus, one possibility is that satiety results from a decrease in the reward associated with mouth wetting during a drinking episode. Beverages can differ in their satiating ability. This variability may be related to their mouth-wetting characteristic, and may be reflected in a shift in their acceptability when the mouth becomes dry. Physically drying the mouth appears to increase the acceptability of beverages that are either cold or acidic. It may be significant that two important determinants of mouth wetting are temperature and acidity. Cold or acidic beverages are also likely to be regarded as 'thirst-quenching.' Thus, shifts in acceptability, 'thirst quenching' and satiety may all be related to the mouth-wetting properties of a beverage. The extent to which this coincidence is meaningful warrants further investigation. However, if a common underlying process exists, then this may help to elucidate reasons for voluntary dehydration and aberrant drinking behavior in the elderly.

Animals↗