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.     

Implicit /explicit memory versus analytic/nonanalytic processing: Rethinking the mere exposure effect

In studies of the mere exposure effect, rapid presentation of items can increase liking without accurate recognition. The effect on liking has been explained as a misattribution of fluency caused by prior presentation. However, fluency is also a source of feelings of familiarity. It is, therefore, surprising that prior experience can enhance liking without also causing familiarity-based recognition. We suggest that when study opportunities are minimal and test items are perceptually similar, people adopt an analytic approach, attempting to recognize distinctive features. That strategy fails because rapid presentation prevents effective encoding of such features; it also prevents people from experiencing fluency and a consequent feeling of familiarity. We suggest that the liking-without-recognition effect results from using an effective (nonanalytic) strategy in judging pleasantness, but an ineffective (analytic) strategy in recognition. Explanations of the mere exposure effect based on a distinction between implicit and explicit memory are unnecessary.     

Acoustic measures of stutterers'' speech following an intensive therapy program

Characteristics of consonant-vowel duration and vocal fundamental frequency (F₀) are reported for 12 school-age stuttering males. Subjects' speech was recorded pre- and post- therapy and at 2-mo follow-up. Mean F₀ and voice onset time values remained stable from pretherapy to 2-mo follow-up, and an increase of 12% vocalized time was maintained across all posttherapy samples. It is suggested that increases in speech fluency may not be accompanied by changes in fundamental timing gestures. Increased speech fluency may be accomplished through increases in vocalized time permitting adjustments in motor sequencing which accompany stuttering.     

The limits of child effects: evidence for genetically mediated child effects on corporal punishment but not on physical maltreatment

Research on child effects has demonstrated that children's difficult and coercive behavior provokes harsh discipline from adults. Using a genetically sensitive design, the authors tested the limits of child effects on adult behavior that ranged from the normative (corporal punishment) to the nonnormative (physical maltreatment). The sample was a 1994-1995 nationally representative birth cohort of 1,116 twins and their families who participated in the Environmental Risk Longitudinal Study. Results showed that environmental factors accounted for most of the variation in corporal punishment and physical maltreatment. However, corporal punishment was genetically mediated in part, and the genetic factors that influenced corporal punishment were largely the same as those that influenced children's antisocial behavior, suggesting a child effect. The authors conclude that risk factors for maltreatment are less likely to reside within the child and more likely to reside in characteristics that differ between families.     

Age differences in veridical and false recall are not inevitable: The role of frontal lobe function

The relationship of neuropsychological measures of frontal lobe function to age differences in false recall was assessed using the Deese/Roediger-McDermott associative false memory paradigm (Deese, 1959; Roediger & McDermott, 1995). As other studies have found, older adults were less likely to correctly recall studied items and more likely to falsely recall highly related but nonpresented items than were younger adults. When older adults were divided based on a composite measure of frontal lobe functioning, this age difference was found only for low frontal lobe functioning individuals. High frontal lobe functioning older adults and young adults had equivalent levels of false recall, as well as equivalent levels of veridical recall. These results suggest that age differences in memory may be due to declines in frontal lobe function. More important, our findings indicate that declines in veridical recall and increases in false recall are not an inevitable consequence of aging.     

Predictors of Cancer Worry in Unaffected Women from High Risk Breast Cancer Families: Risk Perception is not the Primary Issue

Some women at increased familial risk of breast cancer experience elevated levels of cancer-specific worry, which can possibly act as a barrier to screening, and may be a significant factor in decisions regarding risk-reducing surgery. The aim of this study was to comprehensively examine predictors of cancer-specific worry in high risk women and to test a model which proposes that perceived breast cancer risk mediates the impact of other factors on worry. 1,437 unaffected women from high risk breast cancer families completed questionnaires and interviews. Path analysis was used to test the model of potential predictors of cancer worry, including familial, personal and psychological variables, mediated via perceived cancer risk. Levels of cancer-specific worry were generally low despite an average perceived risk of 50.3%. The goodness-of-fit of the proposed model was poor, explaining only 9% of the variance for perceived risk and 10% of the variance for cancer specific worry. An alternative model of a direct relationship between all of the predictor variables and cancer worry, explained 24% of the variation in cancer worry. General anxiety, perceived risk, the stressful impact of recent cancer related events, a relative risk greater than 10, being closer in age to the youngest breast cancer diagnosis in family, and knowledge of personal mutation status, all independently contributed to cancer worry. Addressing general affective responses, experiences of recent cancer related events, in addition to education about personal risk, should be considered in counselling women with elevated cancer worry. Risk perception appears to act independently of other factors in its formulation and impact on cancer worry. Further research on the way in which women come to perceive their risk is indicated. The kConFab Psychosocial Group are (in alphabetical order of institution): Brain and Mind Institute, University of Sydney, Australia (I Hickie) Department of Haematology and Medical Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia (K-A Phillips) Department of Medical Oncology, Prince of Wales Hospital, Randwick, Australia (B Bennett, B Meiser, K Tucker) Department of Oncology, St Vincent’s Hospital, Melbourne, Australia (S-A MaLachlan) Department of Psychological Medicine, Royal North Shore Hospital, St Leonards, Australia (C Tennant); Medical Psychology Research Unit, University of Sydney, Australia (P Butow, M Price).     

The effect of target group size on risk judgments and comparative optimism: the more, the riskier

In 5 experiments, college students exhibited a group size effect on risk judgments. As the number of individuals in a target group increased, so did participants' judgments of the risk of the average member of the group for a variety of negative life events. This happened regardless of whether the stimuli consisted of photographs of real peers or stick-figure representations of peers. As a result, the degree to which participants exhibited comparative optimism (i.e., judged themselves to be at lower risk than their peers) also increased as the size of the comparison group increased. These results suggest that the typical comparative optimism effect reported so often in the literature might be, at least in part, a group size effect. Additional results include a group size effect on judgments of the likelihood that the average group member will experience positive and neutral events and a group size effect on perceptual judgments of the heights of stick figures. These latter results, in particular, support the existence of a simple, general cognitive mechanism that integrates stimulus numerosity into quantitative judgments about that stimulus.     

From Ghosts to Ancestors: The Psychoanalytic Vision of Hans Loewald

The American Journal of Psychoanalysis -