Models,monitoring, and the mind: Comments on Wansink and Chandon's “Slim by Design”

Wansink and Chandon have examined the “mindlessness” that is often evident in everyday food intake. In this commentary, we focus on four issues raised by Wansink and Chandon's paper: (1) the distinction between food choice and food intake; (2) their model of food intake (and how it compares and contrasts with our own model of food intake); (3) the role of monitoring in the control of food intake; and (4) the meaning of “mindless” eating. In each case we find value in Wansink and Chandon's proposals but also an opportunity for further analysis and refinement.     

Emotional stimuli exert parallel effects on attention and memory

Because emotional and neutral stimuli typically differ on non-emotional dimensions, it has been difficult to determine conclusively which factors underlie the ability of emotional stimuli to enhance immediate long-term memory. Here we induced arousal by varying participants' goals, a method that removes many potential confounds between emotional and non-emotional items. Hungry and sated participants encoded food and clothing images under divided attention conditions. Sated participants attended to and recalled food and clothing images equivalently. Hungry participants performed worse on the concurrent tone-discrimination task when they viewed food relative to clothing images, suggesting enhanced attention to food images, and they recalled more food than clothing images. A follow-up regression analysis of the factors predicting memory for individual pictures revealed that food images had parallel effects on attention and memory in hungry participants, so that enhanced attention to food images did not predict their enhanced memory. We suggest that immediate long-term memory for food is enhanced in the hungry state because hunger leads to more distinctive processing of food images rendering them more accessible during retrieval.     

Neural correlates of affective influence on choice

Making the right choice depends crucially on the accurate valuation of the available options in the light of current needs and goals of an individual. Thus, the valuation of identical options can vary considerably with motivational context. The present study investigated the neural structures underlying context dependent evaluation. We instructed participants to choose from food menu items based on different criteria: on their anticipated taste or on ease of preparation. The aim of the manipulation was to assess which neural sites were activated during choice guided by incentive value, and which during choice based on a value-irrelevant criterion. To assess the impact of increased motivation, affect-guided choice and cognition-guided choice was compared during the sated and hungry states. During affective choice, we identified increased activity in structures representing primarily valuation and taste (medial prefrontal cortex, insula). During cognitive choice, structures showing increased activity included those implicated in suppression and conflict monitoring (lateral orbitofrontal cortex, anterior cingulate). Hunger influenced choice-related activity in the ventrolateral prefrontal cortex. Our results show that choice is associated with the use of distinct neural structures for the pursuit of different goals.     

Do drives drive the train of thought?—Effects of hunger and sexual arousal on mind-wandering behavior

Physiological needs that are currently unfulfilled are known to affect human cognition and behavior. The present study investigates whether and how the temporary activation of two primary physiological needs, namely hunger and sexual arousal, influence both the frequency and the contents of mind-wandering episodes. To induce hunger, one group of participants fasted for a minimum of five hours whereas another group of participants was exposed to audio material with explicit sexual content to provoke sexual arousal. Both groups as well as an additional control group, which had not received hunger instructions and had not been exposed to arousing material of any kind beforehand, performed a reading task during which mind wandering was assessed using a standard experience-sampling method. Results showed that acute hunger but not elevated sexual arousal renders the occurrence of mind-wandering episodes more likely. Induction of both hunger and sexual arousal rendered the occurrence of need-related off-task thoughts more likely and changed time orientations of mind wandering. The present findings are well in line with the assumption that unfulfilled needs regularly achieve cognitive priority and extend the cognitive-priority idea to self-generated thoughts.     

Motivation modulates the effect of approach on implicit preferences

With three studies, we investigated whether motivational states can modulate the formation of implicit preferences. In Study 1, participants played a video game in which they repeatedly approached one of two similar beverages, while disregarding the other. A subsequent implicit preference for the target beverage emerged, which increased with participants’ thirst. In Study 2, participants approached one brand of potato chips while avoiding the other: Conceptually replicating the moderation observed in Study 1, the implicit preference for the approached brand increased with the number of hours from last food intake. In Study 3, we experimentally manipulated hunger, and the moderation effect emerged again, with hungry participants displaying a higher implicit preference for the approached brand, as compared to satiated participants. In the three studies, the moderation effect was not paralleled in explicit preferences although the latter were affected by the preference inducing manipulation. Theoretical implications and open questions are discussed.     

Rats learn to eat more to avoid hunger

Several recent experiments have provided evidence that the ingestion of a distinctive food by rats can be a learnt instrumental act as well as an associatively conditioned reaction. In the previous work, maintenance food was withheld for shorter and longer durations on different days following access to the training food. Extra eating before the longer fast was interpreted as avoidance of hunger. This interpretation was based on the evidence showing that extra eating as a result of classical conditioning comes from pairing food stimuli with the presence of little or no hunger because of repletion with energy nutrients. The theory that the extra eating arose from a response-depletion contingency was tested in the present experiment by training rats on only a long fast or only a short fast. Greater increase in intake was seen before the longer fast. The results also replicated previously seen cycles of increase, decrease, and renewed increase in putative deficit-avoidant eating over about three trials, indicating that the extra eating reduces the response-reinforcing hunger and that the consequent part-extinction restores reinforcement. The shape of the learning curve was consistent with these cycles occurring from the start of training, further supporting the view that the increase in food intake before a long delay in refeeding is hunger-reinforced instrumental behaviour.     

Alimentary epigenetics: A developmental psychobiological systems view of the perception of hunger, thirst and satiety

Hunger, thirst and satiety have an enormous influence on cognition, behavior and development, yet we often take for granted that they are simply inborn or innate. Converging data and theory from both comparative and human domains, however, supports the conclusion that the phenomena hunger, thirst and satiety are not innate but rather emerge probabilistically as a function of experience during individual development. The metatheoretical perspective provided by developmental psychobiological systems theory provides a useful framework for organizing and synthesizing findings related to the development of the perception of hunger, thirst and satiety, or alimentary interoception. It is argued that neither developmental psychology nor the psychology of eating and drinking have adequately dealt with the ontogeny of alimentary interoception and that a more serious consideration of the species-typical developmental system of food and fluid intake and the many modifications that have been made therein is likely necessary for a full understanding of both alimentary and emotional development.