It is demonstrated that the popular three-parameter logistic model can lead to markedly inaccurate individual ability level estimates for mixture populations. A theoretically and empirically important setting is initially considered where (a) in one of two subpopulations (latent classes) the two-parameter logistic model holds for each item in a…

Signaled active avoidance (SigAA) is the key experimental procedure for studying the acquisition of instrumental responses toward conditioned threat cues. Traditional analytic approaches (e.g., general linear model) often obfuscate important individual differences, although individual differences in learned responses characterize both animal and…

In the behavioral sciences, a popular approach to describe and predict behavior is cognitive modeling with adjustable parameters (i.e., which can be fitted to data). Modeling with adjustable parameters allows, among other things, measuring differences between people. At the same time, parameter estimation also bears the risk of overfitting. Are…

Individual differences in impulsive choice behavior have been linked to a variety of behavioral problems including substance abuse, smoking, gambling, and poor financial decision-making. Given the potential importance of individual differences in impulsive choice as a predictor of behavioral problems, the present study sought to measure the extent…

This study explored the prevalence of violent behaviors in patients who are addicted to drugs. A sample of 252 addicted patients (203 male and 49 female) who sought outpatient treatment was assessed. Information on violent behaviors, sociodemographic factors, consumption factors (assessed by the European version of the Addiction Severity Index…

Relations between infant-mother attachment security at 15 months and infants' (N = 206) joint attention behaviors (a) with an experimenter at 8 and 15 months, and (b) with their mothers at 15 months were investigated. No concurrent or longitudinal relations were observed between attachment security and infants' tendency to respond to an…

Ahmad R. Hariri, recipient of the Award for Distinguished Scientific Early Career Contributions to Psychology, is cited for pioneering contributions to understanding the neurobiological mechanisms driving individual differences in complex behavior traits. Hariri has integrated molecular genetics, neuropharmacology, neuroimaging, and psychology in…

In 2007-08 and 2008-09, 2,500 randomly-selected middle school students completed an annual survey on school climate and character development. In examining differences based upon grade, gender, race/ethnicity, school, and length of program participation, significant differences were found for all but length of program participation. Responses of…

Dogs likely were the first animals to be domesticated and as such have shared a common environment with humans for over ten thousand years. Only recently, however, has this species' behavior been subject to scientific scrutiny. Most of this work has been inspired by research in human cognitive psychology and suggests that in many ways dogs are…

The effect of force requirements on response effort was examined using outbred (CD-1) mice trained to press a disk with their snout. Lateral peak forces greater than 2 g were defined as threshold responses (i.e., all measured responses). Different force requirements were used to define criterion responses (a subclass of threshold responses) that…

Despite its avowed goal of understanding individual behavior, the field of behavior analysis has largely ignored the determinants of consistent differences in level of performance among individuals. The present article discusses major findings in the study of individual differences in intelligence from the conceptual framework of a functional…

The purpose of the present study was to examine social anxiety as a predictor of positive emotions using a short-term prospective design. We examined whether the effects of social anxiety on positive emotions are moderated by tendencies to openly express or suppress emotions. Over the course of a 3-month interval, people with excessive social…

A review of Learning Theory and Mental Development (Academic Press, 1970) by William K. Estes. (DS)