Monkeys are rational!

Five squirrel monkeys showed a significant Symbolic Distance Effect (SDE) when tested on procedures designed to incorporate reaction time (RT) measures within the five-term series (“transitive inference”) task. Taken together with the high levels of transitive choice obtained by these subjects, this result shows that monkeys have met choice and reaction time criteria perceived by many as indexical of “linear representation”. Explicit evaluation of the representational implications of the SDE was subsequently undertaken in three-choice transfer tests, which initially revealed consistent deviations from the ranks predicted on a linear model. Extensive testing with the triadic method, however, elicited spontaneous improvement in overall choice ranking according to a linear principle. Further decomposition of the RT data showed that the irregularities in the initial transfer behaviour are by no means paradoxical. The ordinal separation data structure, from which the SDE is derived, masks two separate populations of scores--one fast and relatively undifferentiated, the other slow and based on judgements with poorly encoded items. And it is these factors, not inter-item distance, which, we argue, are the main determiners of the SDE. Whilst this phenomenon is thus only weakly indexical of principled linear representation, we contend that new (triad-based) ranking evidence suggests that monkeys may be capable of seriation as well as transitivity.     

Plasticity associated with escalated operant ethanol self-administration during acute withdrawal in ethanol-dependent rats requires intact matrix metalloproteinase systems

Repeated cycles of ethanol intoxication and withdrawal associated with dependence induce neuroadaptations in a variety of brain systems. Withdrawal-induced negative emotional states can be ameliorated by ethanol consumption; a learned process termed negative reinforcement. Accordingly, a dependence-induced phenotype is escalated ethanol self-administration. Matrix metalloproteinases (MMPs) are proteolytic enzymes which degrade the extracellular matrix to allow for synaptic reorganization and plasticity. To test the hypothesis that an intact MMP system is required for animals to learn about the negative reinforcing effects of ethanol and display escalated self-administration during acute withdrawal when ethanol-dependent, male Wistar rats were trained to self-administer ethanol and then assigned to either acute or chronic MMP inhibition treatment groups. The chronic treatment group received intracerebroventricular (ICV) infusions of the broad spectrum MMP inhibitor FN-439 or artificial cerebrospinal fluid (aCSF) via osmotic minipumps during a 1 month ethanol dependence induction period and subsequent post-dependence induction self-administration sessions that occurred during acute withdrawal. The acute treatment group only received ICV FN-439 or aCSF on the day of self-administration sessions following dependence induction during acute withdrawal. The results showed that inhibition of MMPs attenuated escalated ethanol self-administration following chronic and acute exposure conditions. Furthermore, once learning (i.e., plasticity) had occurred, MMP inhibition had no impact on escalated response patterns and animals previously subjected to MMP inhibition that did not escalate evidenced normal escalations in operant ethanol self-administration once FN-439 treatments were terminated. Thus, the present data identified that an intact MMP system is required for the escalated responding that occurs during acute withdrawal in dependent animals and implicate such escalation as a learned response.     

A preliminary examination of the effect of massage on state body image

Evidence suggests positive effects of massage on psychological health; however, little is known about the effects of massage on body image. This research examined the effect of massage on state body image as well as relations between trait body image and attitudes toward massage. Forty-nine female university students were randomly assigned to either a massage condition or a control condition. It was hypothesized that participants in the massage condition would report improved state body image following the intervention when compared to participants in the control condition. As predicted, participants in the massage condition reported a more favorable state body image than participants in the control condition post-manipulation. Certain body image evaluations were moderately associated with views that massage is pleasurable, with the link between Body Areas Satisfaction and viewing massage as pleasurable reaching significance. Research is needed to determine the mechanism/s through which massage improves body image.     

Why good job performance may (not) be rewarded: Sex Factors and Career Development

An experiment tested the effects of three sex variables on managerial career evaluations. The variables were sex of evaluator, sex of manager (evaluatee), and predominate sex of manager's subordinates. Each subject evaluated four managers, one in each possible combination of the last two independent variables, in an “in basket” format. All four situations included comparable managerial performance data. Subjects evaluated each manager in terms of size of a deserved salary increase, probable performance if promoted, promotability, and probability of attaining 5-year tenure. There were no differences in evaluations between male and female evaluators. Manager's sex and predominate subordinate sex frequently interacted. The interactions were interpreted as a sex-matching bias which can inappropriately benefit managers of opposite sex subordinates and hinder careers of managers with subordinates of their own sex.     

The mini-IPIP scales: tiny-yet-effective measures of the Big Five factors of personality

The Mini-IPIP, a 20-item short form of the 50-item International Personality Item Pool-Five-Factor Model measure (Goldberg, 1999), was developed and validated across five studies. The Mini-IPIP scales, with four items per Big Five trait, had consistent and acceptable internal consistencies across five studies (= at or well above .60), similar coverage of facets as other broad Big Five measures (Study 2), and test-retest correlations that were quite similar to the parent measure across intervals of a few weeks (Study 4) and several months (Study 5). Moreover, the Mini-IPIP scales showed a comparable pattern of convergent, discriminant, and criterion-related validity (Studies 2-5) with other Big Five measures. Collectively, these results indicate that the Mini-IPIP is a psychometrically acceptable and practically useful short measure of the Big Five factors of personality.     

Differentiation between and within groups: the influence of individualist and collectivist group norms

The power of individualist and collectivist group norms to influence intergroup and inter‐individual differentiation was examined in three studies. Study 1 revealed that intergroup differentiation was lower when group norms prescribed individualism than when they prescribed collectivism. However, inter‐individual differentiation was higher when group norms endorsed individualism than when they promoted collectivism. In Studies 2 and 3 we found evidence for the moderating effect of group salience on the relationship between norms and differentiation. Specifically, the effect that individualist group norms reduced intergroup differentiation but enhanced inter‐individual differentiation was more pronounced when group salience was high rather than low. This finding demonstrates that conformity to a group norm prescribing individualism influences the manner in which positive differentiation is expressed. The discussion focuses on the caveats of introducing individualist group norms when attempting to reduce intergroup differentiation. Copyright © 2006 John Wiley & Sons, Ltd.     

Trumping the causal influence account of causation

Here is a simple counterexample to David Lewis’s causal influence account of causation, one that is especially illuminating due to its connection to what Lewis himself writes: it is a variant of his trumping example