Choice behavior of rats searching for food

The experiments reported here were designed to determine if several general principles drawn from appetitively motivated discrimination experiments in standard laboratory apparatus might also apply to food-searching behavior under more naturalistic conditions. Food-deprived rats searched for food in an open observation area. Choice behavior after finding food and after not finding food was analyzed. In all cases, not finding food in a possible food location was sufficient to direct subsequent search behavior away from that location for the remainder of the day's test. Finding food had variable effects on subsequent choice behavior, depending on the number of locations that actually contained food and the number of days food was in one location before being shifted to another. The results indicate that the rat's search strategy was influenced by food availability and distribution in ways that are predicted by discrimination learning experiments.     

Vision with spatial inversion: A follow-up study

The Psychological Record -     

Species-specific defense reactions and avoidance learning

Bolles (1970) proposed a theory of avoidance learning, the species-specific defense reaction (SSDR) hypothesis, which emphasized innate constraints on the response repertoire of rats in aversive situations and minimized the role of reinforcement in avoidance learning. The present paper describes Bolles’ (1970, 1971, 1972, 1975, 1978) development of SSDR theory and reviews the empirical tests of its assumptions and predictions. It is concluded that the SSDRs described by Bolles, along with some others, are highly probable in aversive situations but that the response repertoire is not limited to them. Further, there is strong evidence for reinforcement effects in the establishment and maintenance of at least some avoidance responses.     

Violent groups

This article reviews relevant empirical studies and theoretical formulations in an effort to gain insight into the many violenceprone groups that have come to public attention in recent years. Research findings show group members tend to score high on variables like anger at family members and overcontrolled hostility, often are in developmental transition at the time they join the groups, and gain relief from significant emotional distress through group membership. Leader characteristics, group norm forming and group control processes particular to these kinds of groups are also described in an effort to develop further understanding.Parts of this paper were presented in New York City at a September 1979 symposium on forensic psychology and psychiatry sponsored by the New York Academy of Science.     

Effects of previous delay of reward,generalized effort,and deprivation on impulsiveness

Two experiments investigated the effects of learning and motivational variables upon rats' degree of impulsiveness (choice of a small, immediate reward versus a large, delayed reward). In Experiment 1, food was presented in one of four ways for 24 sessions: fixed-ratio lever pressing requirement, continuous-reinforcement lever-pressing requirement, long intervals between free food presentations, or short intervals between free food presentations. Exposure to the long intervals produced less subsequent impulsiveness in 48 choice trials than did the short intervals, there being no effect of the instrumental requirement. In Experiment 2, there were 48 choice trials in which two hunger levels were combined factorially with two delays of reward for the self-control alternative. Hunger level did not affect implusiveness when there was a short delay, but high hunger increased the impulsiveness when there was a long delay. These results indicate that impulsiveness is affected by prior learning and current motivation. Implications for Baum, Rachlin, and Green's matching formula and for frustration theory are discussed.     

A base-free measure of change

A model for the measurement of the discrepancy between two scores is presented and discussed as a paradigm for the study of growth or experimentally produced change. The model assumes two tests or measures differing in complexity, and it analyzes the true difference between the test scores into a component that is entirely dependent on the first or base-line test and a second component that is entirely independent of it. Equations for estimating both components are given and these are compared with other measurement efforts with similar goals.