Serotonin enhances the impact of health information on food choice

Serotonin has been implicated in promoting self-control, regulation of hunger and physiological homeostasis, and regulation of caloric intake. However, it remains unclear whether the effects of serotonin on caloric intake reflect purely homeostatic mechanisms, or whether serotonin also modulates cognitive processes involved in dietary decision making. We investigated the effects of an acute dose of the serotonin reuptake inhibitor citalopram on choices between food items that differed along taste and health attributes, compared with placebo and the noradrenaline reuptake inhibitor atomoxetine. Twenty-seven participants attended three sessions and received single doses of atomoxetine, citalopram, and placebo in a double-blind randomised cross-over design. Relative to placebo, citalopram increased choices of more healthy foods over less healthy foods. Citalopram also increased the emphasis on health considerations in decisions. Atomoxetine did not affect decision making relative to placebo. The results support the hypothesis that serotonin may influence food choice by enhancing a focus on long-term goals. The findings are relevant for understanding decisions about food consumption and also for treating health conditions such as eating disorders and obesity.M.J.C. was supported by a Sir Henry Wellcome Postdoctoral Fellowship (092217/Z/10/Z) and a Wellcome Trust ISSF award. L.C. is the Director of the Centre for Gambling Research at the University of British Columbia, which is funded by the Province of British Columbia and the British Columbia Lottery Corporation. L.C. has provided consultancy work for, and received royalty payments from, Cambridge Cognition Ltd. L.C. has received a speaker honorarium from Svenska Spel. U.M. has received honoraria for consultancy, educational talks and/or sponsorship for attendance at scientific meetings from Eli Lilly, Flynn Pharma/Medice, Heptares, Janssen, Lundbeck, Shire and Sunovion. T.W.R. has provided consultancy work for Cambridge Cognition, Lundbeck, Otsuka, Shire. T.W.R. has received royalty payments from Cambridge Cognition (CANTAB); Research Grants; Lundbeck. T.W.R. has received editorial honoraria from Springer Verlag, Elsevier. The Behavioural and Clinical Neuroscience Institute was supported by a joint award from the Wellcome Trust and the MRC G10001354

Evidence for surprise minimization over value maximization in choice behavior

Classical economic models are predicated on the idea that the ultimate aim of choice is to maximize utility or reward. In contrast, an alternative perspective highlights the fact that adaptive behavior requires agents' to model their environment and minimize surprise about the states they frequent. We propose that choice behavior can be more accurately accounted for by surprise minimization compared to reward or utility maximization alone. Minimizing surprise makes a prediction at variance with expected utility models; namely, that in addition to attaining valuable states, agents attempt to maximize the entropy over outcomes and thus 'keep their options open'. We tested this prediction using a simple binary choice paradigm and show that human decision-making is better explained by surprise minimization compared to utility maximization. Furthermore, we replicated this entropy-seeking behavior in a control task with no explicit utilities. These findings highlight a limitation of purely economic motivations in explaining choice behavior and instead emphasize the importance of belief-based motivations

Context-dependent preferences in starlings: linking ecology, foraging and choice

Foraging animals typically encounter opportunities that they either pursue or skip, but occasionally meet several alternatives simultaneously. Behavioural ecologists predict preferences using absolute properties of each option, while decision theorists focus on relative evaluations at the time of choice. We use European starlings (Sturnus vulgaris) to integrate ecological reasoning with decision models, linking and testing hypotheses for value acquisition and choice mechanism. We hypothesise that options' values depend jointly on absolute attributes, learning context, and subject's state. In simultaneous choices, preference could result either from comparing subjective values using deliberation time, or from processing each alternative independently, without relative comparisons. The combination of the value acquisition hypothesis and independent processing at choice time has been called the Sequential Choice Model. We test this model with options equated in absolute properties to exclude the possibility of preference being built at the time of choice. Starlings learned to obtain food by responding to four stimuli in two contexts. In context [AB], they encountered options A5 or B10 in random alternation; in context [CD], they met C10 or D20. Delay to food is denoted, in seconds, by the suffixes. Observed latency to respond (Li) to each option alone (our measure of value) ranked thus: LA≈LC<LB<<LD, consistently with value being sensitive to both delay and learning context. We then introduced simultaneous presentations of A5 vs. C10 and B10 vs. C10, using latencies in no-choice tests to predict sign and strength of preference in pairings. Starlings preferred A5 over C10 and C10 over B10. There was no detectable evaluation time, and preference magnitude was predictable from latency differentials. This implies that value reflects learning rather than choice context, that preferences are not constructed by relative judgements at the time of choice, and that mechanisms adapted for sequential decisions are effective to predict choice behaviour.This work was supported by Biotechnology and Biological Sciences Research Council (BBSRC) Grant BB/G007144/1 to AK www.bbsrc.ac.uk; TM was supported by a Doctoral Grant from the Portuguese Foundation for Science and Technology (FCT) www.fct.pt/index.phtml.en. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Measuring perceived exercise capability and investigating its relationship with childhood obesity: a feasibility study.

BACKGROUND/OBJECTIVES: According to the COM-B ('Capability', 'Opportunity', 'Motivation' and 'Behaviour') model of behaviour, three factors are essential for behaviour to occur: capability, opportunity and motivation. Obese children are less likely to feel capable of exercising. The implementation of a new methodological approach to investigate the relationship between perceived exercise capability (PEC) and childhood obesity was conducted, which involved creating a new instrument, and demonstrating how it can be used to measure obesity intervention outcomes. SUBJECTS/METHODS: A questionnaire aiming to measure perceived exercise capability, opportunity and motivation was systematically constructed using the COM-B model and administered to 71 obese children (aged 9-17 years (12.24±0.2.01), body mass index (BMI) standard deviation scores (SDS) 2.80±0.660) at a weight-management camp in northern England. Scale validity and reliability was assessed. Relationships between PEC, as measured by the questionnaire, and BMI SDS were investigated for the children at the weight-management camp, and for 45 Spanish schoolchildren (aged 9-13 years, (10.52±1.23), BMI SDS 0.80±0.99). A pilot study, demonstrating how the questionnaire can be used to measure the effectiveness of an intervention aiming to bring about improved PEC for weight-management camp attendees, was conducted. No participants withdrew from these studies. RESULTS: The questionnaire domain (exercise capability, opportunity and motivation) composite scales were found to have adequate internal consistency (a=0.712-0.796) and construct validity (χ(2)/degrees of freedom=1.55, root mean square error of approximation=0.072, comparative fit index=0.92). Linear regression revealed that low PEC was associated with higher baseline BMI SDS for both UK (b=-0.289, P=0.010) and Spanish (b=-0.446, P=0.047) participants. Pilot study findings provide preliminary evidence for PEC improvements through intervention being achievable, and measurable using the questionnaire. CONCLUSIONS: Evidence is presented for reliability and validity of the questionnaire, and for feasibility of its use in the context of a childhood obesity intervention. Future research could investigate the link between PEC and childhood obesity further

Two Kinds of Adaptation, Two Kinds of Relativity

This paper presents a review of adaptation concepts at the evolutionary, environmental, neural, sensory, mental and mathematical levels, including Helson’s and Parducci’s theories of perception and category judgments. Two kinds of adaptation can be clearly distinguished. The first, known as level adaptation, refers to the shift of the neutral perception level to the average stimulus value. It results in a single reference point and stimuli changes represented in absolute terms. This concept is employed by Prospect Theory, which assumes that gains and losses are perceived as monetary amounts. The second kind of adaptation refers to the adjustment of perception sensitivity to stimuli range. It results in two reference points (minimum and maximum stimulus) and stimuli changes perceived in relative terms. Both range adaptation and range relativity are well documented phenomena and have even been confirmed by the creators of Prospect Theory. This makes room for another decision making theory based on the range relativity approach. As shown by Kontek (2009), such a theory would not require the concept of probability weighting to describe lottery experiments or behavioral paradoxes