Chimpanzees demonstrate individual differences in social information use

Studies of transmission biases in social learning have greatly informed our understanding of how behaviour patterns may diffuse through animal populations, yet within-species inter-individual variation in social information use has received little attention and remains poorly understood. We have addressed this question by examining individual performances across multiple experiments with the same population of primates. We compiled a dataset spanning 16 social learning studies (26 experimental conditions) carried out at the same study site over a 12-year period, incorporating a total of 167 chimpanzees. We applied a binary scoring system to code each participant’s performance in each study according to whether they demonstrated evidence of using social information from conspecifics to solve the experimental task or not (Social Information Score—‘SIS’). Bayesian binomial mixed effects models were then used to estimate the extent to which individual differences influenced SIS, together with any effects of sex, rearing history, age, prior involvement in research and task type on SIS. An estimate of repeatability found that approximately half of the variance in SIS was accounted for by individual identity, indicating that individual differences play a critical role in the social learning behaviour of chimpanzees. According to the model that best fit the data, females were, depending on their rearing history, 15–24% more likely to use social information to solve experimental tasks than males. However, there was no strong evidence of an effect of age or research experience, and pedigree records indicated that SIS was not a strongly heritable trait. Our study offers a novel, transferable method for the study of individual differences in social learning.     

Children's memory for complex autobiographical events: Does spacing of repeated instances matter?

Often, when children testify in court they do so as victims of a repeated offence and must report details of an instance of the offence. One factor that may influence children's ability to succeed in this task concerns the temporal distance between presentations of the repeated event. Indeed, there is a substantial amount of literature on the “spacing effect” that suggests this may be the case. In the current research, we examined the effect of temporal spacing on memory reports for complex autobiographical events. Children participated in one or four play sessions presented at different intervals. Later, children were suggestively questioned, and then participated in a memory test. Superior recall of distributed events (a spacing effect) was found when the delay to test was 1?day (Experiment 1) but there was little evidence for a spacing effect when the delay was 1 week (Experiment 2). Implications for understanding children's recall of repeated autobiographical events are discussed.     

Latent growth curve analysis of fear during a speech task before and after treatment for social phobia

Models of social phobia highlight the importance of anticipatory anxiety in the experience of fear during a social situation. Anticipatory anxiety has been shown to be highly correlated with performance anxiety for a variety of social situations. A few studies show that average ratings of anxiety during the anticipation and performance phases of a social situation decline following treatment. Evidence also suggests that the point of confrontation with the feared stimulus is the peak level of fear. No study to date has evaluated the pattern of anxious responding across the anticipation, confrontation, and performance phases before and after treatment, which is the focus of the current study. Socially phobic individuals (N = 51) completed a behavioral avoidance task before and after two types of manualized cognitive behavioral therapy, and gave ratings of fear during the anticipation and performance phases.Results from latent growth curve analysis were the same for the two treatments and suggested that before treatment, anxiety sharply increased during the anticipation phase, was highly elevated at the confrontation, and gradually increased during the performance phase. After treatment, anxiety increased during the anticipation phase, although at a much slower rate than at pretreatment, peaked at confrontation, and declined during the performance phase. The findings suggest that anticipatory experiences are critical to the experience of fear for public speaking and should be incorporated into exposures.     

Survey return rates for multiple-authored versus single-authored covering letters

Differences in response rates to a three-wave mail survey were assessed when the covering letters were signed by three versus one researcher. 375 surveys including covering letters signed by three researchers and 375 surveys including covering letters signed by one researcher were sent. A follow-up mailing was used to increase the response rate. 199 surveys were returned (53.5%) in which the covering letter had three researchers, and 218 when the covering letter had one researcher (58.7%), not a significantly different distribution.     

Judging the fairness of voice-based participation across multiple and interrelated stages of decision making

Recent multifoci research reports that multiple sources of justice exist in organizations. In expanding this framework, we address how judgments of overall procedural fairness and behavioral intentions are influenced by different experiences of voice-based participation across a multi-stage decision-making process. The results of two experiments were consistent with a fairness theory framework. Overall, decision procedures were judged to be the fairest and the intention to volunteer was highest when participants were allowed voice in their team and when their team was allowed voice by organizational authorities. When voice was denied by both the team and the organization or was denied by either party, fairness ratings, and participant intentions were depressed and did not significantly differ from each other. This pattern of results suggests that individuals are influenced by transactions across decision-making stages and that such interdependence should be considered when attempting to understand the meaningfulness of voice-based participation.     

Distinguishing novelty and familiarity effects in infant preference procedures

This paper considers possible problems researchers might face when interpreting the results of studies that employ variants of the preference procedure. Infants show a tendency to shift their preference from familiar to novel stimuli with increasing exposure to the familiar stimulus, a behaviour that is exploited by the habituation paradigm. This change in attentional preference with exposure leads us to suggest that researchers interested in infants' pre‐experimental or spontaneous preferences should beware of the potentially confounding effects of exposing infants to familiarization trials prior to employing the preference procedure. The notion that infant attentional preference is dynamic also calls into question the use of the direction of post‐familiarization preference per se when interpreting the knowledge or strategies available to infants. We look into the results of a cross‐modal word learning study to show how the interpretation of results may be difficult when infants exhibit a significant preference in an unexpected direction. As a possible solution to this problem we propose that significant preferences in both directions should be sought at multiple intervals over time. Copyright © 2004 John Wiley & Sons, Ltd.     

A global factor in the Hermann grid illusion or an artifact?

In the first of the present experiments, subjects were required to estimate the strength of the Hermann grid illusion in grids containing various numbers of intersectionseven though those grids were not actually presented. The positive relationship found by Wolfe (1984) for real grids was, nevertheless, replicated. It is argued that this suggests that a response bias might have been the source of his effect (although other possibilities are also noted). In addition, in a second experiment, subjects who were not aware of the fact that grid size was being manipulated (i.e., between subjects) showed no consistent effect of that factor, thus supporting the same suggestion.