The generality of learned helplessness in the rat

Two experiments were simultaneously conducted in which two different groups of 40 rats each were exposed to one of two different stressors. In both experiments half the subjects were pretreated with shock, half with underwater exposure. For each pretreatment stressor, half the subjects were allowed to escape, the other half were not. The experiments differed in the test task used. Approximately 24 hr after pretreatment, one-half the subjects from each pretreatment group received 20 water-escape trials in an underwater maze, the other half received 20 shock-escape trials in a two-way shuttle box. The subjects in each of the inescapable pretreatment conditions were slower to escape in the subsequent shock-escape and water-escape tasks when compared with subjects in the corresponding escapable pretreatment condition. The “learned helplessness” effect appeared to be no smaller when aversive stimuli were changed between pretreatment and test than when they remained the same.     

Feedback during exposure to inescapable shocks and subsequent shock-escape performance

In two experiments, we assessed the ability of a feedback stimulus during helplessness training to reduce the performance deficits common to inescapable shock. In each experiment, four groups of rats were exposed to either escapable shock (E), inescapable shock with a feedback stimulus following shock termination (Y-FS), inescapable shock with no feedback stimulus (Y-NFS), or no shock (N). The feedback stimulus eliminated the interference effects of inescapable shock when tested with an FR-3 lever press escape task (Experiment 1) or on an FR-1 task with a 3-s delay between the response and shock termination (Experiment 2). These results suggest that stress-induced biochemical changes may mediate the interference effects seen in inescapably shocked rats.     

Introduction to the Special Section on Mixture Modeling in Personality Assessment

Latent variable models offer a conceptual and statistical framework for evaluating the underlying structure of psychological constructs, including personality and psychopathology. Complex structures that combine or compare categorical and dimensional latent variables can be accommodated using mixture modeling approaches, which provide a powerful framework for testing nuanced theories about psychological structure. This special series includes introductory primers on cross-sectional and longitudinal mixture modeling, in addition to empirical examples applying these techniques to real-world data collected in clinical settings. This group of articles is designed to introduce personality assessment scientists and practitioners to a general latent variable framework that we hope will stimulate new research and application of mixture models to the assessment of personality and its pathology.     

An empirical examination of distributional assumptions underlying the relationship between personality disorder symptoms and personality traits

This article examines the relationship between personality disorder (PD) symptoms and personality traits using a variety of distributional assumptions. Prior work in this area relies almost exclusively on linear models that treat PD symptoms as normally distributed and continuous. However, these assumptions rarely hold, and thus the results of prior studies are potentially biased. Here we explore the effect of varying the distributions underlying regression models relating PD symptomatology to personality traits using the initial wave of the Longitudinal Study of Personality Disorders (N = 250; Lenzenweger, 1999), a university-based sample selected to include PD rates resembling epidemiological samples. PD symptoms were regressed on personality traits. The distributions underlying the dependent variable (i.e., PD symptoms) were variously modeled as normally distributed, as counts (Poisson, Negative-Binomial), and with two-part mixture distributions (zero-inflated, hurdle). We found that treating symptoms as normally distributed resulted in violations of model assumptions, that the negative-binomial and hurdle models were empirically equivalent, but that the coefficients achieving significance often differ depending on which part of the mixture distributions are being predicted (i.e., presence vs. severity of PD). Results have implications for how the relationship between normal and abnormal personality is understood. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Is regret for inaction relatively self‐enhancing?

Previous accounts of regret suggest that people report greater regret for inaction than for action because the former is longer lasting and more painful than the latter. We suggest instead that the tendency for people's greatest regrets to concern inaction more than action may be due to the relatively self‐enhancing nature of regrets for inaction. In Study 1 we asked people to think about their greatest recent regret and to code it as being due to action or inaction. In Study 2 participants described their greatest regret from across their entire life. In both studies we observed an inaction effect only amongst individuals high in self‐esteem (HSE). In Study 2 we found that the inaction effect was confined to HSE people whose greatest regret was personal in nature. These results support the claim that regret for inaction is relatively self‐enhancing and suggest that the inaction effect found in real‐life regrets may be due, in part at least, to the self‐enhancement goals of HSE individuals. Copyright © 2005 John Wiley & Sons, Ltd.