Chimpanzees (Pan troglodytes) can wait,when they choose to: a study with the hybrid delay task

Self-control has been studied in nonhuman animals using a variety of tasks. The inter-temporal choice (ITC) task presents choices between smaller–sooner (SS) and larger–later (LL) options. Using food amounts as rewards, this presents two problems: (a) choices of the LL option could either reflect self-control or instead result from animals’ difficulty with pointing to smaller amounts of food; (b) there is no way to verify whether the subjects would not revert their choice for the LL option, if given the opportunity to do so during the ensuing delay. To address these problems, we have recently introduced a new protocol, the hybrid delay task, which combines an initial ITC with a subsequent accumulation phase in which selection of the SS option leads to its immediate delivery, but choice of the LL option then leads to one-by-one presentation of those items that continues only as long as the subject does not eat any of the accumulated items. The choice of the LL option therefore only reflects self-control when the number of items obtained from LL choices during the accumulation phase is higher than what could be received in the SS option. Previous research with capuchin monkeys demonstrated that their apparent self-control responses in the ITC task may have overestimated their general self-control abilities, given their poor performance in the hybrid delay task. Here, chimpanzees instead demonstrated that their choices for the LL option in the ITC phase of the hybrid delay task were confirmed by their ability to sustain long delays during accumulation of LL rewards.     

The bad taste of social ostracism: The effects of exclusion on the eating behaviors of African-American women

African-American women experience disproportionately higher rates of obesity than do Caucasian women. The stress African-American women encounter from experiences of discrimination may influence their eating behaviours, which could contribute to weight gain. Emotional eating theory suggests some people increase their intake of high-calorie foods to cope with stressful experiences. We investigated the effects of social exclusion by other African-American women or by Caucasian women for African-American women’s distress and food consumption using a laboratory paradigm. As hypothesised, there were main effects of ostracism and interactions between ostracism and race, although not all of the interactions took the expected form. As hypothesised, African-American women ate more potato crisps after being excluded by Caucasians than by African-Americans. Unexpectedly, African-American women who were excluded by other African-American women self-reported more emotional distress than did African-American women excluded by Caucasian women. These findings suggest that ostracism by both in-group and out-group members are disturbing, although people may respond to in-group and out-group exclusion in different ways. Directions for future research are suggested that could elucidate the circumstances under which different emotional and behavioural coping responses are employed.     

The inconsistency with which raters weight and combine information across targets

To assign an overall performance rating to a target, a rater must weight and combine various pieces of specific performance information about that target. Policy‐capturing research has demonstrated that individual differences in raters can influence the way raters combine specific performance information. The current study examined information processing from a different perspective by exploring the possibility that target differences may also influence the way raters weight and combine performance information. Raters (N = 146) rated each of six targets on six specific performance dimensions and on overall performance. Sequential moderation analyses indicated that targets influenced the way raters, as a group, combined information across targets. These results lend support to the inference that overall performance ratings may not be comparable across targets, that is, they may not reflect the same underlying performance across targets.     

The psychology of face construction: Giving evolution a helping hand

Face construction by selecting individual facial features rarely produces recognisable images. We have been developing a system called EvoFIT that works by the repeated selection and breeding of complete faces. Here, we explored two techniques. The first blurred the external parts of the face, to help users focus on the important central facial region. The second, manipulated an evolved face using psychologically‐useful ‘holistic’ scales: age, masculinity, honesty, etc. Using face construction procedures that mirrored police work, a large benefit emerged for the holistic scales; the benefit of blurring accumulated over the construction process. Performance was best using both techniques: EvoFITs were correctly named 24.5% on average compared to 4.2% for faces constructed using a typical ‘feature’ system. It is now possible, therefore, to evolve a fairly recognisable composite from a 2 day memory of a face, the norm for real witnesses. A plausible model to account for the findings is introduced. Copyright © 2010 John Wiley & Sons, Ltd.     

‘And what about residential…?’ Re‐conceptualizing residential treatment as a stop‐gap service for youth with emotional and behavioral disorders

The need for residential services for youth with the most intractable emotional and behavioral problems continues to exist despite advances made in developing community‐based systems of care. Residential treatment centers (RTCs), considered one of the most restrictive service settings, have changed little over the years and have not fared well in outcome evaluations. Despite these factors, admissions to RTCs continue to increase. In an attempt to contemporize and bring the RTC more in line with current practice, a stop‐gap model of service delivery is recommended. The stop‐gap model, incorporating evidence‐based practices, is intended to have an immediate and positive impact on the barrier behaviors that keep youths in the most restrictive environments. The twofold goal of the stop‐gap model is to interrupt the youth's downward spiral imposed by increasingly disruptive behavior and, simultaneously, to prepare the post‐discharge environment for the youth's timely reintegration. Strategies for evaluating the effectiveness of the stop‐gap model are recommended. Copyright © 2004 John Wiley & Sons, Ltd.     

Romantic involvement often reduces men's testosterone levels--but not always: the moderating role of extrapair sexual interest

Testosterone (T) appears to facilitate what biologists refer to as mating effort--the investment of time and energy into same-sex competition and mate-seeking behavior. Multiple studies show that men who are romantically involved (i.e., are paired) have lower T than single men, which may be due to a facultative adjustment by men of T levels in response to lower demands for mating effort. The authors proceeded on the basis of the idea that men who retain interests in sexual opportunities with women other than a primary partner continue to dedicate more time and energy to mating effort when romantically paired, and so they predicted that the association between relationship status and T depends on men's extrapair sexual interests. Study 1 used the Sociosexual Orientation Inventory to measure extrapair sexual interests, whereas Study 2 used a broader measure to examine this interaction. Both studies found support for it. These results have implications for an understanding of the biosocial regulation of men's behavior in romantic relationships.     

Patterns of brain acetylcholine release predict individual differences in preferred learning strategies in rats

Acetylcholine release was measured simultaneously in the hippocampus and dorsal striatum of rats before and during training on a maze that could be learned using either a hippocampus-dependent spatial strategy or a dorsal striatum-dependent turning strategy. A probe trial administered after rats reached a criterion of 9/10 correct responses revealed that about half of the rats used a spatial strategy and half a turning strategy to solve the task. Acetylcholine release in the hippocampus, as well as the ratio of acetylcholine release in the hippocampus vs. the dorsal striatum, measured either before or during training, predicted these individual differences in strategy selection during learning. These findings suggest that differences in release of acetylcholine across brain areas may provide a neurobiological marker of individual differences in selection of the strategies rats use to solve a learning task.     

Anxiety in rats selectively bred for Fast and Slow kindling rates: situation-specific outcomes

Rats selectively bred for amygdala excitability, realized by fast or slow kindling epileptogenesis, were previously reported to exhibit differential levels of anxiety. Although the Slow kindling rats generally appeared more anxious in several behavioral tests, under certain test conditions the Fast kindling rats displayed greater anxiety or stressor reactivity. The present investigation confirmed that in a test of anxiety comprising suppression of consumption of a palatable snack in an unfamiliar environment, the Slow kindling rats exhibited greater anxiety and that this effect was attenuated by diazepam. Likewise, the acoustic startle response was greater in the Slow kindling rats. However, the fear-potentiated startle response was more pronounced in Fast kindling rats, particularly among females, irrespective of whether the test parameters elicited moderate or high startle amplitudes. The elevated startle in the Slow rats, and the fear potentiated startle in the Fast rats, were attenuated by diazepam. These data indicate the need to differentiate subtypes of anxiety in animal models, and raise the issue that anxiety elicited by specific environmental triggers may interact with genetically determined trait characteristics.     

Early Verb Learning: How Do Children Learn How to Compare Events?

An important problem verb learners must solve is how to extend verbs. Children could use cross-situational information to guide their extensions; however, comparing events is difficult. In 2 studies, researchers tested whether children benefit from initially seeing a pair of similar events (“progressive alignment”) while learning new verbs and whether this influence changes with age. In Study 1, 2.5- and 3.5-year-old children participated in an interactive task. Children who saw a pair of similar events and then varied events were able to extend verbs at test and differed from a control group; children who saw 2 pairs of varied events did not differ from the control group. In Study 2, events were presented on a monitor. Following the initial pair of events that varied by condition, a Tobii x120 eye tracker recorded 2.5-, 3.5-, and 4.5-year-olds’ fixations to specific elements of events (areas of interest) during the 2nd pair of events, which were the same across conditions. After seeing the pair of events that were highly similar, 2.5-year-olds showed significantly longer fixation durations to agents and to affected objects as compared with the all-varied condition. At test, 3.5-year-olds were able to extend the verb, but only in the progressive alignment condition. These results are important because they show children’s visual attention to relevant elements in dynamic events is influenced by their prior comparison experience, and they show that young children benefit from seeing similar events as they learn to compare events to each other.