Reinforcement learning in the brain

A wealth of research focuses on the decision-making processes that animals and humans employ when selecting actions in the face of reward and punishment. Initially such work stemmed from psychological investigations of conditioned behavior, and explanations of these in terms of computational models. Increasingly, analysis at the computational level has drawn on ideas from reinforcement learning, which provide a normative framework within which decision-making can be analyzed. More recently, the fruits of these extensive lines of research have made contact with investigations into the neural basis of decision making. Converging evidence now links reinforcement learning to specific neural substrates, assigning them precise computational roles. Specifically, electrophysiological recordings in behaving animals and functional imaging of human decision-making have revealed in the brain the existence of a key reinforcement learning signal, the temporal difference reward prediction error. Here, we first introduce the formal reinforcement learning framework. We then review the multiple lines of evidence linking reinforcement learning to the function of dopaminergic neurons in the mammalian midbrain and to more recent data from human imaging experiments. We further extend the discussion to aspects of learning not associated with phasic dopamine signals, such as learning of goal-directed responding that may not be dopamine-dependent, and learning about the vigor (or rate) with which actions should be performed that has been linked to tonic aspects of dopaminergic signaling. We end with a brief discussion of some of the limitations of the reinforcement learning framework, highlighting questions for future research.     

Motivational correlates of need for cognition

Need for cognition is usually characterized as an intrinsic desire to engage in challenging intellectual activity. In achievement situations, however, it could be associated with more extrinsic goals such as success or the avoidance of failure. Three experiments examined this possibility. Participants in all studies were led to believe they would perform either an easy or a difficult intellectual task that they were likely to fail. After inducing this expectation, indices of extrinsic motivation were obtained. Participants with high need for cognition became more motivated to avoid negative consequences of their behavior (e.g., failure) when they expected the task they would perform to be difficult. In contrast, participants with low need for cognition were not appreciably affected by these expectancies. The anticipation of engaging in intellectual activity apparently stimulates different motives in people with high and low need for cognition, and the mindset induced by these motives influences their later behavioral decisions. Copyright © 2008 John Wiley & Sons, Ltd.     

A Test of Positive Illusions Versus Shared Reality Models of Relationship Satisfaction Among Gay, Lesbian, and Heterosexual Couples

According to the positive illusions model ( Murray, Holmes, & Griffin, 1996a ), people in romantic relationships are more satisfied when they view their partners more favorably than the partners see themselves. By contrast, shared reality theory ( Hardin & Conley, 2001 ) emphasizes the benefits of perceiving a partner as the partner sees himself or herself. We analyzed archived data from the American Couples Study ( Blumstein & Schwartz, 1983 ) to test the applicability of the positive illusions model to gay and lesbian relationships. Structural equation models demonstrated that the positive illusions model effectively explains relationships among lesbian, gay, heterosexual cohabitating, and married couples.     

Eating Attitudes and Dieting Behavior Among Religious Subgroups of Israeli-Arab Adolescent Females

Objectives The aim of the study was to compare the eating attitudes and behaviors, including weight concerns and dieting behavior, among three religious subgroups (Moslems, Druze, and Christians) and three age subgroups (12–13, 14–15, and 16–18 years old) of Israeli-Arab adolescent females. Methods The sample consisted of 1141 Israeli-Arab adolescent females, including 926 (81.2%) Moslem, 128 (11.2%) Christian, and 87 (7.6%) Druze schoolgirls in the seventh to twelfth grades. Participants were assessed using the EAT–26 questionnaire. Results The results showed that 75% of the students had a negative EAT-26 score (>20) and that 25% of the students had a positive EAT-26 score (<20). No significant differences were found in total scores, subscale scores, or scores above 20 between the age subgroups or the religious subgroups. The results demonstrated a high prevalence of disturbed eating attitudes and behaviors among Israeli-Arab adolescent schoolgirls. Discussion Higher prevalence of disturbed eating attitudes found among Israeli-Arab schoolgirls as compared to their Jewish counterparts. Although our sample is a communal based, there still remains an open question as to why the desired “slenderness culture” evident in the results is not reflected in the number of ED clinic referrals, among clinical population. These discrepancies were discussed in light of ethnicity-specific factors that may influence the perceived severity of eating disorders and the receptiveness of primary practitioners to address them.     

Use of a structured investigative protocol enhances the quality of investigative interviews with alleged victims of child sexual abuse in Britain

One hundred alleged victims of child sexual abuse (aged 4–13; M = 9.3 years) were interviewed by police investigators about their alleged experiences. Half of the children were interviewed using the National Institute of Child Health and Human Development (NICHD) structured interview Protocol, whereas the other children, matched with respect to their age, relationship with the alleged perpetrator, and seriousness of the alleged offenses, were interviewed by investigators following the Memorandum of Good Practice. Protocol‐guided interviews elicited more information using free‐recall invitations and less information using directive, option‐posing and suggestive questions than did standard Memorandum interviews. There were no age differences in the proportion of total information provided in response to open‐ended invitations in either condition, but there was a significant increase with age in the proportion of central information provided in response to open‐ended invitations. Published in 2008 by John Wiley & Sons, Ltd.     

The effects of nonconsciously priming emotion concepts on behavior

Current empirical evidence regarding nonconsciously priming emotion concepts is limited to positively versus negatively valenced affect. This article demonstrates that specific, equally valenced emotion concepts can be nonconsciously activated, remain inaccessible to conscious awareness, and still affect behavior in an emotion-specific fashion. In Experiment 1A, participants subliminally primed with guilty emotion adjectives showed lower indulgence than did participants subliminally primed with sad emotion adjectives; even after the addition of a 5-min time delay, these results were replicated in Experiment 1B. Participants in the different priming conditions showed no differences in their subjective emotion ratings and were unaware of the emotion prime or concept activation. Experiments 2A and 2B replicated these findings using a helping measure, demonstrating that individuals primed with guilt adjectives show more helping than do individuals primed with sadness adjectives. In all studies, effects were moderated by individuals' specific emotion-response habits and characteristics.     

Age, gender, and level of activity as moderators of personal incentives to physical activity in Israel

The authors conducted an exploratory study with Israeli adults examining their personal incentives for physical activity (e.g., appearance, weight management). The participants formed a sample of 379 physically active Israelis, aged 20-89 years, divided into 3 age groups and 3 levels of activity. The authors found a similar profile for men and women for most incentives, with men scoring more highly than did women on only competition and fitness. Participants in the highest level of activity attributed greater importance to all incentives than did those in the other levels, and older adults attributed less importance to all incentives except for health benefits. The findings are relevant for planning activities intended to encourage adults to engage in more physical activity.