Male Wistar rats show individual differences in an animal model of conformity

Conformity refers to the act of changing one’s behaviour to match that of others. Recent studies in humans have shown that individual differences exist in conformity and that these differences are related to differences in neuronal activity. To understand the neuronal mechanisms in more detail, animal tests to assess conformity are needed. Here, we used a test of conformity in rats that has previously been evaluated in female, but not male, rats and assessed the nature of individual differences in conformity. Male Wistar rats were given the opportunity to learn that two diets differed in palatability. They were subsequently exposed to a demonstrator that had consumed the less palatable food. Thereafter, they were exposed to the same diets again. Just like female rats, male rats decreased their preference for the more palatable food after interaction with demonstrator rats that had eaten the less palatable food. Individual differences existed for this shift, which were only weakly related to an interaction between their own initial preference and the amount consumed by the demonstrator rat. The data show that this conformity test in rats is a promising tool to study the neurobiology of conformity.     

The end-state comfort effect facilitates joint action

Motor experts can accurately predict the future actions of others by observing their movements. This report describes three experiments that investigate such predictions in everyday object manipulations and test whether these predictions facilitate responses to the actions of others. Observing video excerpts showing an actor reaching for a vertically mounted dial, participants in Experiment 1 needed to predict how the actor would rotate it. Their predictions were specific to the direction and extent of the dial rotation and improved proportionate to the length of the video clip shown. Testing whether such predictions facilitate responses, in the subsequent experiments responders had to undo an actor's actions, back-rotating a dial (Exp 2) and a bar (Exp 3). The responders' actions were initiated faster when the actors' movements obeyed the so-called end-state comfort principle than when they did not. Our experiments show that humans exploit the end-state comfort effect to tweak their predictions of the future actions of others. The results moreover suggest that the precision of these predictions is mediated by perceptual learning rather than by motor simulation.     

Psychometric Evaluation of the Borderline Personality Disorder Severity Index-IV-Adolescent Version and Parent Version

The Borderline Personality Disorder Severity Index-IV-adolescent and parent versions (BPDSI-IV-ado/p) are DSM-IV based semi-structured interviews for the assessment of the severity of symptoms of borderline personality disorder (BPD) in adolescents. The present study evaluates the psychometric properties of the BPDSI-IV-ado/p. The interviews were administered to 122 adolescents, aged 14-19 years and their parents/caretakers who were referred to mental health centres for emotion regulation problems, and to 45 healthy controls. The interrater reliability and internal consistency of all nine subscales (following the nine BPD symptoms in DSM-IV) proved to be good to excellent. Discriminant, concurrent, and construct validity were satisfactory. Cut-off scores that optimize sensitivity and specificity were derived. Informant agreement between adolescents and parents/caretakers was modest. The results of this study suggest that the BPDSI-IV adolescent and parent versions are valid and reliable instruments for the assessment of BPD symptom severity in adolescents.     

Patient experiences with treatment in private practice compared with public mental health services

The study compared patient experiences with psychiatric treatment provided by private practitioners and public outpatient clinics. Questionnaires were completed by 642 outpatients in private practice and 6,677 outpatients in public clinics. The questionnaire included a measure of patient experiences comprising six items: treatment outcome, enough time for contact and dialogue with clinician, clinicians' understanding of patient's situation, suitability of therapy and treatment, clinician follow-up of planned actions, and influence on treatment. Patients in private practice had generally better experiences than patients in public outpatient treatment. The difference between private and public patients was largest for patients with poor self-evaluated mental health or those who had just one consultation in the previous three months. Private practitioners appear to have an important role in mental health services delivery, and patients have relatively good experiences with services. Further studies that assess the patient - clinician interaction in different mental health services may give further insights into potential service improvements.     

A new perspective on human reward research: How consciously and unconsciously perceived reward information influences performance

The question of how human performance can be improved through rewards is a recurrent topic of interest in psychology and neuroscience. Traditional, cognitive approaches to this topic have focused solely on consciously communicated rewards. Recently, a largely neuroscience-inspired perspective has emerged to examine the potential role of conscious awareness of reward information in effective reward pursuit. The present article reviews research employing a newly developed monetary-reward-priming paradigm that allows for a systematic investigation of this perspective. We analyze this research to identify similarities and differences in how consciously and unconsciously perceived rewards impact three distinct aspects relevant to performance: decision making, task preparation, and task execution. We further discuss whether conscious awareness, in modulating the effects of reward information, plays a role similar to its role in modulating the effects of other affective information. Implications of these insights for understanding the role of consciousness in modulating goal-directed behavior more generally are discussed.     

Effort responses to suboptimal reward cues are related to striatal dopaminergic functioning

Reward cues have been found to increase the investment of effort in tasks even when cues are presented suboptimally (i.e. very briefly), making them hard to consciously detect. Such effort responses to suboptimal reward cues are assumed to rely mainly on the mesolimbic dopamine system, including the ventral striatum. To provide further support for this assumption, we performed two studies investigating whether these effort responses vary with individual differences in markers of striatal dopaminergic functioning. Study 1 investigated the relation between physical effort responses and resting state eye-blink rate. Study 2 examined cognitive effort responses in relation to individually averaged error-related negativity. In both studies effort responses correlated with the markers only for suboptimal, but not for optimal reward cues. These findings provide further support for the idea that effort responses to suboptimal reward cues are mainly linked to the mesolimbic dopamine system, while responses to optimal reward cues also depend on higher-level cortical functions.