Retrieval-induced forgetting and unwanted thought intrusions

The act of retrieving an existing memory has been found to inhibit the recall of related memories, a phenomenon known as retrieval-induced forgetting (RIF). The purpose of the present study was to investigate the hypothesis that individuals with a strong RIF effect might be better at suppressing unwanted intrusive thoughts. In Experiment 1 the relationship between RIF and the prevalence of intrusive thoughts was investigated using a sample of 58 normal British participants, who completed three different questionnaires to measure their susceptibility to intrusive thoughts, obsessional thoughts, and impulsive thoughts. Their susceptibility to RIF was also measured, using the standard procedure introduced by Anderson, Bjork, and Bjork (1994). The results showed a significant RIF effect, and, although no significant correlations were found between RIF strength and any of the three measures of intrusive thoughts, there was some evidence to suggest a possible relationship between RIF and intrusive thoughts. In an effort to clarify these inconclusive findings, Experiment 2 investigated the relationship between RIF and intrusive thoughts in a different and more varied population sample, consisting of 90 normal members of the Greek population. Experiment 2 confirmed the RIF effect, but no significant association was found between RIF and intrusive thoughts. These findings therefore offer no support for the hypothesis that RIF assists the suppression of intrusive thoughts in normal individuals.     

A Structural Approach to the Understanding of Causes, Effects, and Judgment. Review of Causality: Models, Reasoning, and Inference, by Judea Pearl

Judea Pearl is Professor Emeritus of Computer Science and Statistics and Director of the Cognitive Systems Laboratory at University of California, Los Angeles. He has authored the books Heuristics (1984) and Probabilistic Reasoning in Intelligent Systems (1988). He has also published close to 300 articles on automated reasoning, learning, and inference. In 1999, he was awarded the IJCAI Research Excellence Award in Artificial Intelligence fundamental work in heuristic search, reasoning under uncertainty, and causality.Susan F. Butler is a doctoral student at Tufts University. Her work is in modeling of judgment and decision making, stochastic processes, and the examination of choice behavior under uncertainty.     

Accuracy of recall among “eyewitnesses” to a simulated robbery: Intrapersonal and stimulus determinants

This study is a laboratory analogue investigation of variables that impinge upon the recall of detail about a simulated act of armed robbery among “eyewitnesses.” Specifically, this study sought to determine (1) whether recall of detail by Ss who watch the videotape of a simulated “armed robbery” taken by surveillance camera in a “convenience” store varies according to (a) the dress and appearance of the presumed “robber,” (b) the gender of the victim of the “robbery,” and/or (c) the gender of the “eyewitness”; and (2) whether such recall varies according to S’s inventoried psychological “needs.” Ss viewed the videotape of the simulated robbery under one of four conditions representing variations in the dress and appearance (“status”) of the alleged offender and the gender of the alleged victim; completed the Personality Adjective Inventory; and responded to a questionnaire concerning details of the alleged offense. Results indicate that the single statistically significant source of variance in accuracy of recall of detail is the experimentally manipulated “status” of the perpetrator; gender of victim and of subject contribute significantly neither in isolation nor in interaction. Inventoried psychological needs for “autonomy” and “change” are significantly but negatively and weakly correlated with accuracy among women Ss, while “change” alone is so correlated among men Ss. Findings are interpreted in accordance with theory and research in experimental social psychology and psychological criminology bearing upon person perception and role expectancy in relation to behavioral stereotypes. This study was supported in part through the Henry Rutgers Scholars Program at Rutgers College of Rutgers-The State University of New Jersey. The authors express their gratitude to Charles Rouse, Steven Gaynor, April Hayes, Erica Gross, Shawn Kimble, Elizabeth Chen, and Stephanie Bonn; Officer Leroy Washington, Rutgers University Police; and most particularly to Dipak Munsaf, proprietor of Krauszer's Food Store in the sixth ward of the city of New Brunswick.     

Why are there eccentricity effects in visual search? Visual and attentional hypotheses

In standard visual search experiments, observers search for a target item among distracting items. The locations of target items are generally random within the display and ignored as a factor in data analysis. Previous work has shown that targets presented near fixation are, in fact, found more efficiently than are targets presented at more peripheral locations. This paper proposes that the primary cause of this “eccentricity effect” (Carrasco, Evert, Chang, & Katz, 1995) is an attentional bias that allocates attention preferentially to central items. The first four experiments dealt with the possibility that visual, and not attentional, factors underlie the eccentricity effect. They showed that the eccentricity effect cannot be accounted for by the peripheral reduction in visual sensitivity, peripheral crowding, or cortical magnification. Experiment 5 tested the attention allocation model and also showed that RT X set size effects can be independent of eccentricity effects. Experiment 6 showed that the effective set size in a search task depends, in part, on the eccentricity of the target because observers search from fixation outward.     

Temperature reinforcement for visual discrimination training in baby chicks

A fully automated training apparatus, using thermoregulation as performance incentive, was constructed to train baby chicks on visual discrimination and reversal problems. In the base condition, the S is bathed in cold air in a small training cubicle. Two stimuli are back-projected onto two display windows according to a pseudorandom balanced schedule. A peck at the positive stimulus gives convective as well as radiant heat reward with adjustable temperature and duration. A peck at the negative stimulus merely advances the program to the next trial. Permanent printout records give trial-to-trial information on response choice and latency. Performance data of 64 Ss are reported.