A PARADIGM FOR OPERANT CONDITIONING IN BLOW FLIES (PHORMIA TERRAE NOVAE ROBINEAU‐DESVOIDY, 1830)

An operant conditioning situation for the blow fly (Protophormia terrae novae) is described. Individual flies are trained to enter and reenter a hole as the operant response. Only a few sessions of contingent reinforcement are required to increase response rates. When the response is no longer followed by food, the rate of entering the hole decreases. Control procedures revealed that rate of responding is not a simple overall result of feeding or of aging. The flies entered into the hole only if the response was required to obtain the food.     

The social face of emotion recognition: Evaluations versus stereotypes

The goal of the present paper was to demonstrate the influence of general evaluations and stereotype associations on emotion recognition. Earlier research has shown that evaluative connotations between social category members and emotional expression predict whether recognition of positive or negative emotional expressions will be facilitated (e.g. Hugenberg, 2005). In the current paper we tested the hypothesis that stereotype associations influence emotion recognition processes, especially when the difference between valences of emotional expressions does not come into play. In line with this notion, when participants in the present two studies were asked to classify positive versus negative emotional expressions (i.e. happy versus anger, or happy versus sadness), valence congruency effects were found. Importantly, however, in a comparative context without differences in valence in which participants were asked to classify two distinct negative emotions (i.e. anger versus sadness) we found that recognition facilitation occurred for stereotypically associated discrete emotional expressions. With this, the current results indicate that a distinction between general evaluative and cognitive routes can be made in emotion recognition processes.     

Does group efficacy increase group identification? Resolving their paradoxical relationship

Although group identification and group efficacy are both important predictors of collective action against collective disadvantage, there is mixed evidence for their (causal) relationship. Meta-analytic and correlational evidence suggests an overall positive relationship that has been interpreted as consistent with the idea that group identification leads to group efficacy. However, experimental evidence has not supported this causal relationship. To resolve this paradox, we show in an experiment that it is group efficacy that leads to increased group identification because group efficacy puts individuals' identity into action. We discuss the theoretical and practical implications of these findings.     

Leader power and leader self-serving behavior: The role of effective leadership beliefs and performance information

In this research we investigated the role played by leader power in determining leader self-serving behavior. Based on an integration of insights from research on the determinants of leader behavior and the power-approach theory, we hypothesized that with higher leader power leader self-serving behavior is determined more by internal states like effective leadership beliefs and less by external cues like performance information. We found support for this prediction across two experiments and one organizational survey assessing leader behavior along a self-serving–group-serving continuum. Overall, these results suggest that whether leaders benefit the collective or act self-servingly is not a function of their power per se but rather that leader power determines the extent to which internal belief states or external cues influence leader self- versus group-serving behavior.     

Social status as a cue for tacit coordination

The present paper investigates how and when social status may serve as a cue for tacit coordination. In three experimental studies, we demonstrate that low status individuals are inclined to defer to the preferences of high status individuals, thereby facilitating coordination success. Furthermore, we investigate the boundary conditions of this effect. More specifically, we show that social status only facilitates coordination success when the people involved have asymmetric (or conflicting) preferences (Study 2), and when there is a clear social hierarchy (Study 3). In the general discussion, we relate these findings to earlier research on dominance hierarchies, social power, deference and perspective-taking and we provide suggestions for future research.     

Learning a complex motor skill from video and point-light demonstrations

The aim of this study was to compare the learning process of a highly complex ballet skill following demonstrations of point-light and video models. 16 participants divided into point-light and video groups (ns = 8) performed 160 trials of a pirouette, equally distributed in blocks of 20 trials, alternating periods of demonstration and practice, with a retention test a day later. Measures of head and trunk oscillation, coordination disparity from the model, and movement time difference showed similarities between video and point-light groups; ballet experts' evaluations indicated superiority of performance in the video over the point-light group. Results are discussed in terms of the task requirements of dissociation between head and trunk rotations, focusing on the hypothesis of sufficiency and higher relevance of information contained in biological motion models applied to learning of complex motor skills.     

Optimization of Blocked Designs in fMRI Studies

Blocked designs in functional magnetic resonance imaging (fMRI) are useful to localize functional brain areas. A blocked design consists of different blocks of trials of the same stimulus type and is characterized by three factors: the length of blocks, i.e., number of trials per blocks, the ordering of task and rest blocks, and the time between trials within one block. Optimal design theory was applied to find the optimal combination of these three design factors. Furthermore, different error structures were used within a general linear model for the analysis of fMRI data, and the maximin criterion was applied to find designs which are robust against misspecification of model parameters.     

Differential effect of lesion side on intra-individual variability in children with focal lateralized epilepsy

A differential impact of hemispheric side (left vs right) on cognitive measures, specifically Verbal and Performance IQ, has been described previously for both focal onset seizures and lateralized brain lesions. This study revealed a differential effect on intra-individual variability, measured as subtest scaled-score range, on the Dutch WISC-R and WISC-III, in children with epilepsy. The presence of documented brain lesion was associated with elevated variability on the Verbal Scale for the left hemisphere seizure group and with decreased variability on the Verbal and Full Scales for the right hemisphere seizure group.     

Men's sense of humor and women's responses to courtship solicitations: an experimental field study

Producing humor might function as a fitness indicator associated with greater desirability during dating selection. A male confederate in a bar was instructed to tell (or not tell) funny jokes to two other male confederates. A few minutes later, when the second of two male confederates left, the first male confederate asked a female who was near his table and who had heard the funny jokes for her phone number. The previous expression of humor was associated with greater compliance with the male confederate's request and with a higher positive evaluation. The possible effects of humor are discussed from an evolutionary perspective.