Biases and fallacies, memories and predictions: comment on Roy, Christenfeld, and McKenzie (2005)

Comparative theory testing is a useful method for assessing the value of a new theoretical account such as the memory bias account of optimistic time predictions. However, such comparisons can be misleading when they do not carefully consider the domain limitations of the respective theories. M. M. Roy, N. J. S. Christenfeld, and C. R. M. McKenzie have contrasted the memory bias and planning fallacy accounts in their ability to explain the prevalence and degree of optimistic bias in time predictions. However, the authors argue that many of the points of distinction they draw are actually reflections of the domain limitations of the 2 theories. The authors clarify the definition and scope of the planning fallacy account and show how the apparent contradictions diminish or disappear.     

The emergence of homegrown stereotypes

Homegrown stereotypes are generalizations that groups develop about their own typical characteristics. They are a distinct class of in-group stereotypes in the contexts and processes that give rise to them, as well as in their consequences for individual group members. The authors develop the concept of homegrown stereotypes and locate the origins of these stereotypes in self-presentation processes. They discuss the accuracy of these stereotypes and consider their similarities to and differences from a number of related phenomena. An examination of homegrown stereotypes highlights the importance of taking into account the impact of in-group, as well as intergroup, dynamics on the production of stereotypes.     

Aspiration-Based and Reciprocity-Based Rules in Learning Dynamics for Symmetric Normal-Form Games

Psychologically based rules are important in human behavior and have the potential of explaining equilibrium selection and separatrix crossings to a payoff dominant equilibrium in coordination games. We show how a rule learning theory can easily accommodate behavioral rules such as aspiration-based experimentation and reciprocity-based cooperation and how to test for the significance of additional rules. We confront this enhanced rule learning model with experimental data on games with multiple equilibria and separatrix-crossing behavior. Maximum likelihood results do not support aspiration-based experimentation or anticipated reciprocity as significant explanatory factors, but do support a small propensity for non-aspiration-based experimentation by random belief and non-reciprocity-based cooperation.     

Patterns of impaired verbal,spatial, and object working memory after thalamic lesions

Working memory processes in six individuals with isolated thalamic lesions were assessed. Participants were given a verbal, spatial, and object n-back task, each at three levels of task load (1-back, 2-back, and 3-back). Relative to a control group, the patients were impaired on the verbal and spatial n-back tasks, and possibly on the object n-back task as well. None of the patients showed impaired short-term memory as measured by digit span. Group differences on trials measuring matching, sequencing, and inhibitory abilities were consistent with other reports suggesting that thalamic lesions may impair the operation of executive processes.     

Observational Effects on Preference Selection for Four Children on the Autism Spectrum: A Replication

Individuals with autism have been noted to have restricted interests and repetitive behavior such as nonfunctional manipulation of objects. In this study, we used an observational conditioning procedure to switch the preference of items for four individuals diagnosed with autism who are considered lower functioning. The procedure consisted of the participant observing an adult playing with toys that were initially non‐preferred by the participant in a functional and engaging manner. For two participants, results were similar to the findings by Leaf; one participant required additional conditioning procedures, and we were unable to switch the preference for the other participant. Copyright © 2015 John Wiley & Sons, Ltd.     

Is the Bifactor Model a Better Model or Is It Just Better at Modeling Implausible Responses? Application of Iteratively Reweighted Least Squares to the Rosenberg Self-Esteem Scale

Although the structure of the Rosenberg Self-Esteem Scale (RSES) has been exhaustively evaluated, questions regarding dimensionality and direction of wording effects continue to be debated. To shed new light on these issues, we ask (a) for what percentage of individuals is a unidimensional model adequate, (b) what additional percentage of individuals can be modeled with multidimensional specifications, and (c) what percentage of individuals respond so inconsistently that they cannot be well modeled? To estimate these percentages, we applied iteratively reweighted least squares (IRLS) to examine the structure of the RSES in a large, publicly available data set. A distance measure, d_s, reflecting a distance between a response pattern and an estimated model, was used for case weighting. We found that a bifactor model provided the best overall model fit, with one general factor and two wording-related group factors. However, on the basis of d_r?values, a distance measure based on individual residuals, we concluded that approximately 86% of cases were adequately modeled through a unidimensional structure, and only an additional 3% required a bifactor model. Roughly 11% of cases were judged as “unmodelable” due to their significant residuals in all models considered. Finally, analysis of d_s revealed that some, but not all, of the superior fit of the bifactor model is owed to that model's ability to better accommodate implausible and possibly invalid response patterns, and not necessarily because it better accounts for the effects of direction of wording.     

Critical issues in experimental studies of prosociality in non-human species

Prosociality and acts of altruism are defined as behaviours which benefit another with either no gain or some immediate cost to the self. To understand the evolutionary origins of these behaviours, in recent years, studies have extended to primate species; however, studies on non-primates are still scarce. In light of the fact that phylogenetic closeness to humans does not appear to correlate with prosocial tendencies, but rather differences in the propensity towards prosociality may be linked to allomaternal care or collaborative foraging, it appears that convergent selection pressures may be at work in the evolution of prosociality. It would hence seem particularly important to extend such studies to species outside the primate clade, to allow for comparative hypothesis testing of the factors affecting the evolution of prosocial behaviours. In the current review, we focus on the experimental paradigms which have been used so far (i.e. the prosocial choice task, helping paradigms and food-sharing tests) and highlight the strengths and weaknesses of each method. In line with the aim of encouraging a broader comparative approach to the topic of prosociality, particular emphasis is placed on the methodological issues that need to be taken into account. We conclude that although a number of the paradigms used so far may be successfully applied to non-primate species, there is a need to simplify the cognitive demands of the tasks and ensure task comprehension to allow for a ‘fair’ comparative approach of prosocial tendencies across species.