Long-term memory in pigeons: I. The role of discrimination problem difficulty assessed by reacquisition measures II. The role of stimulus modality assessed by generalization slope

Pigeons learned either an easy or a difficult line angle discrimination (Experiment 1) or wavelength discrimination (Experiment 2), and then they were given a reacquisition test of retention after delays of 1 min, 1 day, or 1 week. Both percentage of responses to the S+ in the initial 10-trial block and number of blocks to criterion showed a progressive memory loss which was greater for the difficult problem. These results extend recent findings by using a free operant rather than a discrete trial task and by varying problem difficulty by altering the dimensional separation between training stimuli. In Experiment 3, pigeons were given variable interval training with either a wavelength or a line angle stimulus, and then they were tested for generalization in extinction after delays of 1 min, 1 day, and 1 week. With both dimensions, the relative gradients became progressively flatter with increasing delay intervals. This replicates earlier findings and extends them to the line angle dimension. The evidence of substantial forgetting in the first 24 h in all three experiments suggests that operant free-response procedures are more sensitive to forgetting effects than are discrete trial tasks.     

REPLY TO COMMENTS ON "HUXLEY'S EVOLUTION AND ETHICS IN SOCIOBIOLOGICAL PERSPECTIVE"

Abstract. I agree with comments suggesting that humans must make an unremitting effort to expand a circle of sympathy for others. However, I disagree with the idea, expressed by everyone except Sarah Hrdy, that evolution is in some sense consistently good.     

Predictors of organizational commitment: The study of part-time army reservists

A predictive model built upon a multiple role conflict/felt responsibility conceptual framework and containing six previously untested predictors and nine previously tested organizational-related predictors of organizational commitment was investigated. The sample consisted of two battalions of U.S. Army Reserve members. Stepwise multiple regression analysis utilizing a double cross-validation design on each battalion was the data analytic technique. Increased job satisfaction and stronger intent to stay consistently entered each equation as the first and second predictors, respectively. Group cohesion also appeared in more than one equation. The variance explained across the four cross-validated samples averaged .46 and the results were very stable. The importance of the investigation of commitment for this part-time, voluntary organization was discussed, as were future research directions regarding organizational commitment.     

Memory without organization: Properties of a model with random storage and undirected retrieval

A very simple spatial model of memory storage and retrieval is described, analyzed, and discussed. The postulated memory is without organization in the sense that neither the place of storage nor the order of search during retrieval is influenced by the nature of the information being stored or retrieved. The memory consists of a three-dimensional space containing a large number of homogeneously distributed loci at which data may be stored. Data received near each other in time are stored at nearby locations. Access is by an undirected expanding-sphere search. The model exhibits a wide variety of quantitatively and qualitatively humanlike behavior with respect to both standard learning and forgetting paradigms and with respect to frequency effects and other phenomena in word processing.     

Social skills training for juvenile delinquents

Twenty-seven incarcerated juvenile delinquents matched on the number of previous offenses, age, WISC-R IQ, and locus of control were assigned to a Social Skills. Discussion or Control group. Social skills training consisted of instruction, feedback, modeling, behavior rehearsal, social reinforcement and graduated homework assignments. All subjects were assessed before and after treatment on a variety of self-report, role-play and behavioral measures. Analyses of variance for difference scores indicated that the Social Skills group improved significantly more than the Discussion and Control groups, which did not differ. Appropriate interpersonal skills were learned, state anxiety was reduced, internal locus of control was increased, and significant shifts in adjustment to the institutional program were evidenced for the Social Skills group.     

A developmental study of schedule-induced polydipsia in the rat

Rats 30, 60, 90, and 120 days of age were fed 105 45-mg food pellets on a noncontingent VT 70-sec schedule during 14 daily 2-hr sessions. Every animal became polydipsic on this schedule when compared with a schedule in which 105 pellets were presented at the beginning of the session. Mean polydipsic ratios (schedule intake/control intake) ranged from 2.9–5.4. Water intakes (milliliters per 100g body weight) did not differ during the last five sessions as a function of age. The results are discussed with respect to the generality of the class of adjunctive behaviors.     

The effect of Pavlovian stimuli on the acquisition of a new response

Three experiments explored the effects of response dependent stimuli which have had different types of contingent relationships with positive reinforcement. Results showed consistent differences in the effects of response dependent appetitive Pavlovian CS + s, CS ? s, and truly random control (TRC) stimuli on the acquisition of a new response. These differences were shown in both a free operant and a discrete-trial learning situation. Appetitive Pavlovian CS?s consistently produced lower levels of responding than did TRC stimuli, even in an experimental situation free of possible contrast effects. The results of these experiments extended a contingency analysis of acquired associations to appetitive conditioning and provided a clear demonstration of a conditioned reinforcement effect against a variety of control procedures.     

An analysis of behavior in the hobbits-orcs problem

Young adults solved a problem in which hobbits and orcs had to be transported across a river. In Expt I, a Part-Whole group of subjects solved the problem starting at a different state in the middle and then were given the entire problem. Comparison with a Control group indicated that the initial practice of the Part-Whole group did not facilitate their later performance on the same problem segment, but did facilitate performance in a different portion of the problem. In Expt II, some subjects were given feedback halfway through the problem that they were on the right track. Results gave some support to the notion that a possible difficulty in the problem is the subject's belief that he must have entered a blind alley in the search space. However, other difficulties were also involved. Inferences from several different dependent performance variables, the transfer results, and subjects' comments consistently suggested that subjects solving this problem needed to undergo a number of cognitive changes (3–4) that was smaller than the minimum number of external moves required to solve the problem (11).