The expression of c-Fos and colocalisation of c-Fos and glucocorticoid receptors in brain structures of low and high anxiety rats subjected to extinction trials and re-learning of a conditioned fear response

We designed an animal model to examine the mechanisms of differences in individual responses to aversive stimuli. We used the rat freezing response in the context fear test as a discriminating variable: low responders (LR) were defined as rats with a duration of freezing response one standard error or more below the mean value, and high responders (HR) were defined as rats with a duration of freezing response one standard error or more above the mean value. We sought to determine the colocalisation of c-Fos and glucocorticoid receptors-immunoreactivity (GR-ir) in HR and LR rats subjected to conditioned fear training, two extinction sessions and re-learning of a conditioned fear. We found that HR animals showed a marked decrease in conditioned fear in the course of two extinction sessions (16 days) in comparison with the control and LR groups. The LR group exhibited higher activity in the cortical M2 and prelimbic areas (c-Fos) and had an increased number of cells co-expressing c-Fos and GR-ir in the M2 and medial orbital cortex after re-learning a contextual fear. HR rats showed increased expression of c-Fos, GR-ir and c-Fos/GR-ir colocalised neurons in the basolateral amygdala and enhanced c-Fos and GR-ir in the dentate gyrus (DG) in comparison with LR animals. Our data indicate that recovery of a context-related behaviour upon re-learning of contextual fear is accompanied in HR animals by a selective increase in c-Fos expression and GRs-ir in the DG area of the hippocampus.     

Trolley Dilemma in Papua. Yali horticulturalists refuse to pull the lever

Psychonomic Bulletin & Review - Although many studies show cultural or ecological variability in moral judgments, cross-cultural responses to the trolley problem (kill one person to save five...     

Does Personality Smell? Accuracy of Personality Assessments Based on Body Odour

People are able to assess some personality traits of others based on videotaped behaviour, short interaction or a photograph. In our study, we investigated the relationship between body odour and the Big Five personality dimensions and dominance. Sixty odour samples were assessed by 20 raters each. The main finding of the presented study is that for a few personality traits, the correlation between self‐assessed personality of odour donors and judgments based on their body odour was above chance level. The correlations were strongest for extraversion (.36), neuroticism (.34) and dominance (.29). Further analyses showed that self–other agreement in assessments of neuroticism slightly differed between sexes and that the ratings of dominance were particularly accurate for assessments of the opposite sex. Copyright © 2011 John Wiley & Sons, Ltd.     

Mixed matters: fluency impacts trust ratings when faces range on valence but not on motivational implications

Facial features that resemble emotional expressions influence key social evaluations, including trust. Here, we present four experiments testing how the impact of such expressive features is qualified by their processing difficulty. We show that faces with mixed expressive features are relatively devalued, and faces with pure expressive features are relatively valued. This is especially true when participants first engage in a categorisation task that makes processing of mixed expressions difficult and pure expressions easy. Critically, we also demonstrate that the impact of categorisation fluency depends on the specific nature of the expressive features. When faces vary on valence (i.e. sad to happy), trust judgments increase with their positivity, but also depend on fluency. When faces vary on social motivation (i.e. angry to sad), trust judgments increase with their approachability, but remain impervious to disfluency. This suggests that people intelligently use fluency to make judgments on valence-relevant judgment dimensions – but not when faces can be judged using other relevant criteria, such as motivation. Overall, the findings highlight that key social impressions (like trust) are flexibly constructed from inputs related to stimulus features and processing experience.     

Cooperative behavior of laboratory rats (Rattus norvegicus) in an instrumental task

Cooperation is a cognitively demanding, complex social behavior, found primarily in primates. Here we investigated mutualism in rats (Rattus Norvegicus), a simple form of cooperation in which two subjects work on operant task, receiving immediate and simultaneous sucrose reward for a joint action. To receive the sucrose reward, familiar pairs of rats were required to nose poke simultaneously. Following 44 training days, we examined the relation of social contact and ultrasonic vocalizations to the rat's cooperative behavior by testing the effects of inserting opaque, wire-mesh, or no partition--between subjects. Cooperative behavior (simultaneous nose-poking): (a) increased gradually during initial training; (b) decreased with the opaque partition (restricting visual, acoustic, and physical communication); (c) increased with a wire mesh partition restricting only physical contact); and (d) increased with the number of 50 kHz USV "happy" calls and the intensity of social interaction. The possibility of studying the development of cooperative behavior in laboratory rats using a simple procedure based on commercially available equipment may prove useful in modeling determinants of social behavior.     

Did Venus have long legs? Beauty standards from various historical periods reflected in works of art

Research on perception of attractiveness of leg-to-body ratio (LBR) described here has shown that people prefer relatively long-legged silhouettes (particularly while assessing women). The LBR of attractive women over historical periods (analyses of attractive silhouettes from paintings, sculptures, etc) has been more changeable than that of men. The findings reported here might represent evidence against the cross-cultural universality of the attractiveness of long legs.     

Effect of loudness on reaction time and response force in different motor tasks

Van der Molen and Keuss, in 1979 and 1981, showed that paradoxically long reaction times occur with extremely strong auditory stimuli when the task is difficult, e.g., choice-by-location or Simon paradigm. It was argued that this paradoxical behavior of RT is due to active inhibition of an arousal-dependent bypassing mechanism to prevent false responses. As the peak force, i.e., maximal force exerted by participants on a response key, is considered to be related to immediate arousal, we predicted that for extremely loud stimuli and for difficult tasks, lengthening of RT should be associated with reduction of peak force. Moreover, these effects should be enhanced when emphasis is on accuracy rather than speed. Although the relation between RT and intensity depended on task difficulty, no increase in RT was found for the loudest tones. Moreover, peak force increased monotonically with loudness, showing no tendency to be suppressed for loudest tones and difficult tasks.     

Mechanisms underlying spatial coding in a multiple-item Simon task

Choice responses are faster when target position and response side correspond than when they do not, even if target position is response-irrelevant. This "Simon effect" has also been observed in case of multi-item arrays. Generally, it is assumed that an automatically generated spatial response code is responsible for the effect. The referential-coding account assumes that this code is directly related to the target, although the moment of production of the code is not fully clear. The attention-shift account assumes that the code is directly related to the direction of the most recent attentional shift. An experiment was performed in which left or right target locations were indicated by arrows occurring before (precue), simultaneous with (simcue), or after (postcue) six-element arrays. Overt responses and EEG potentials were recorded. The Simon effect was present in all conditions, and decreased when responses were slower. No relation was found between amplitude of posterior lateralized components and the magnitude of the Simon effect. A posterior contralateral negativity was also found after presenting the arrays in the precue condition, which might reflect the reorienting of attention toward the target position. The results are more favorable to the referential-coding account although this account becomes very similar to the attention-shift hypothesis as the moment of formation of the spatial response code is related to effective target onset rather than to stimulus onset.     

Prototypes are attractive because they are easy on the mind

People tend to prefer highly prototypical stimuli--a phenomenon referred to as the beauty-in-averageness effect. A common explanation of this effect proposes that prototypicality signals mate value. Here we present three experiments testing whether prototypicality preference results from more general mechanisms-fluent processing of prototypes and preference for fluently processed stimuli. In two experiments, participants categorized and rated the attractiveness of random-dot patterns (Experiment 1) or common geometric patterns (Experiment 2) that varied in levels of prototypicality. In both experiments, prototypicality was a predictor of both fluency (categorization speed) and attractiveness. Critically, fluency mediated the effect of prototypicality on attractiveness, although some effect of prototypicality remained when fluency was controlled. The findings were the same whether or not participants explicitly considered the pattern's categorical membership, and whether or not categorization fluency was salient when they rated attractiveness. Experiment 3, using the psychophysiological technique of facial electromyography, confirmed that viewing abstract prototypes elicits quick positive affective reactions.