Reinforcement magnitude effects in first- and second-order conditioning of directed action

Three experiments investigated the effects of reinforcement magnitude on conditioned key pecking in pigeons. Experiment 1, which included between-groups and within-subject designs, yielded significant effects of unconditioned stimulus (US) magnitude on the within-conditioned stimulus (CS) distribution of key pecks and on choice behavior, but no effect on the overall rate of key pecking. Experiment 2 employed a larger US-magnitude difference in a within-subject design. This manipulation resulted in differential rates of key pecking as well as a significant choice effect and differential within-CS key-peck distributions. A second-order conditioning procedure was used in Experiment 3, in which diffuse, visual stimuli (S1's) served as Pavlovian reinforcers for two key-light S2's. The S1 previously paired with a large US was more effective in conditioning second-order key-peck behavior to an S2 than was the S1 paired with a small US. The results of these experiments demonstrate that the associative effects of US magnitude can be expressed in the strength of CS-directed motor responding. The distinctive within-CS key-peck distributions in first-order conditioning suggests an interaction between CS- and US-directed responses.     

Intertrial interval effects on internal stimulus control of behavior in brightness differential conditioning

In Experiment 1, groups were given a trial sequence in differential conditioning in which all S+ trials preceded all S? trials (+? schedule) or one in which some S+ trials followed S? trials (+?+ schedule) and either a 1- or a 30-min intertrial interval (ITI). ITI affected discrimination learning only in the +? schedule condition; schedule affected discrimination only at massed trials. In Experiment.2, all groups received a +?+ schedule. In two groups, given a 1- or 15-min ITI between all trials, discrimination learning was independent of ITI. Discrimination learning was facilitated in two other groups given a 1-min ITI between all trials except between S? and the subsequent S+ trial, when the ITI was either 15 or 60 min. The results were discussed in terms of their implications for internal reward-related stimulus control of behavior in differential conditioning.     

Retrieval processes in fifth graders and adults

This research was concerned with retrieval processes which underlie conceptual clustering. In a free recall task with categorized lists, fifth graders' and adults' retrieval was examined temporally by means of interword response times. List organization and retrieval cue factors were manipulated in order to assess the developmental relevance of an hypothesized three component retrieval model. The results indicated that both age groups used a qualitatively similar retrieval strategy, involving search for and decoding of higher-order memory units. Providing retrieval cues eliminated the category search component, but also increased the likelihood of exhaustive recall attempts under random presentation conditions. The results were discussed in terms of the inter-relationships between storage and retrieval strategies. Age-related differences in retrieval time were attributed to insufficient reorganization during input and failure to attempt to recall all of a category's members.     

Hemispheric asymmetry in memory search for four-letter names and human faces

Two memory search experiments were conducted using vertically oriented four-letter names and human faces as stimuli. Subjects were required to indicate as quickly and as accurately as possible whether or not a single probe stimulus (presented for 150 msec to either the left or right visual field) was contained in a set of 2, 3, 4, or 5 items being held in short-term memory. The probe stimuli were presented alone (clear condition) or centrally embedded in a matrix of dots (degraded condition). In Experiment 1 (involving names), a right visual field/left hemisphere advantage was obtained and pinpointed at the encoding stage rather than at the memory comparison stage of the information-processing system. For Experiment 2 (involving human faces), no hemispheric advantage was readily observed. In each experiment, both the left hemisphere and the right hemisphere employed an abstract memory comparison operation from which the effects of probe degradation have been removed. These results are discussed in terms of their implications for various models of hemispheric asymmetry.     

The precision fluency shaping program: Replication and evaluation

The purpose of this article is to present the results of a two-year project to evaluate the Precision Fluency Shaping Program (Webster, 1980) in a community speech and hearing center. Fifty stutterers participated in therapy. Results indicated that Precision Fluency Shaping was an effective therapy for the treatment of stuttering. In addition, stutterer's perception of their speech changed from pre to post therapy. Follow-up data are presented on 28 clients. Advantages of conducting Precision Fluency Shaping, meeting accountability standards, and procedures for collecting follow-up data are discussed.     

Blocking in successive differential conditioning: Prior acquisition of control by internal cues blocks the acquisition of control by brightness

In each of four experiments the acquisition of discriminative stimulus control by brightness cues (black vs white runway) in a successive go/no-go instrumental discrimination was blocked in groups given prior discrimination training with internal (reward-produced and intertrial interval-related) cues as relevant discriminanda and brightness cues irrelevant. The blocking effects obtained here in instrumental conditioning were substantial and in most cases complete. Blocking occurred whether brightness in Phase I varied across trials but was uncorrelated with reinforcement (varied-irrelevant, V-I, condition) or whether all Phase 1 trials occurred to a single value on the brightness dimension (constant-irrelevant, C-I, condition) which then served as a redundant S+ cue in Phase 2 while the previously unexperienced brightness cue was added to the S- stimulus compound, or vice versa. Blocking in the V-I condition was shown not to be due simply to nondifferential reinforcement of brightness in Phase 1, but to depend on the prior acquisition of discriminative stimulus control by internal cues. As in Pavlovian conditioning, blocking here was an increasing function of amount of prior conditioning to the blocking stimulus. The results encourage the prospect that the procedures used here can be developed into a viable instrumental conditioning companion to the Pavlovian procedures now used almost exclusively to study blocking.     

A critical review of a recent decade of stuttering research

The purpose of the present investigation was to catalogue and evaluate portions of the literature on stuttering from 1967 to 1977. Of particular interest was the identification of the research literature. Of 287 articles located and evaluated, 181 were research reports. These reports were categorized according to topics, subject selection, subjects' characteristics, type of research designs and use of randomization, reliability, and statistical methods. Unhappily, many of the faults identified in reviews ten to twenty years earlier tended to persist, and many of the deficiencies recently cited by authorities in the field were found to characterize this literature.     

Sequential effects on discrimination reversal

In Experiment 1 the sequence of trials to the positive (S+) and negative (S?) discriminanda was varied between groups during acquisition and reversal of a successive brightness discrimination. In Experiments 2 and 3, groups received different reward sequences in Phase 1 within S+. In general, groups given transitions from nonrewarded trials to rewarded trials (N-R transitions) in Phase 1 learned both the original discrimination and its reversal more slowly than groups given schedules devoid of N-R transitions. The results were discussed in relation to previously reported effects of partial reinforcement on acquisition and reversal of a discrimination and the role of sequential variables and internal, reward-produced cues in discrimination learning, reversal learning, and nonreversal shifts.     

Critical procedural variables related to the physiological effects of progressive relaxation: a review.

Twenty-five investigations of the physiological effects of progressive relaxation training were classified according to whether relaxation was found to be superior or equivalent to control conditions. The two sets of studies differed significantly on number of training sessions and in the use of taped vs live administration of training, and they tended to differ in the use of normal vs patient samples. The likelihood of producing significant physiological reductions via progressive relaxation appears to be greater when multi-session, subject-controlled training is conducted with subjects for whom physiological activity contributes to a presenting. clinical problem.     

Evaluating socioeconomic status bias in the WISC-R

The use of intelligence tests in making special education placement decisions for children has come under repeated scrutiny in recent years. Arguments for and against the use of IQs have centered around the issue of test bias. In California a permanent moratorium on the use of intelligence tests in placing minority group children into classes for the educable retarded has been handed down by the court. One defense proposed by advocates of mental testing has been that the tests are biased against socially and economically disadvantaged groups irrespective of race. According to Clarizio (1978), if a test predicts equally well for two groups it can not legitimately be described as biased. The purpose of this investigation was to evaluate the test bias of the Verbal IQ as measured by the Wechsler Intelligence Scale for Children-Revised in relation to predictions of academic achievement in two different socioeconomic status groups. The results indicated that Verbal IQs are not biased with respect to socioeconomic status. Derived regression equations are presented along with an analysis to inspect the statistical power of the original tests.     

The differential reinforcement of reward-produced and response-produced stimuli

In two experiments, groups received successive large-reward trials on odd-numbered days and successive small-reward trials on even-numbered days in the same gray alleyway. This produced a discrimination problem in which the memory of large reward (S^L) was reliably discriminative of large reward and the memory of small reward (S^S) was reliably discriminative of small reward. Intertrial interval (ITI) was varied both between and within groups. In the within-groups manipulation, ITI separating S+ trials differed from that separating S- trials. Experimental groups learned the discrimination, running slower to S^S (S- cue) than to S^L (S+ cue), and showed a negative contrast effect, running slower to S- than a small-reward control group. Discrimination was somewhat faster at massed than at spaced trials. The within-groups manipulation of ITI suggested that the effects of ITI were mediated by time-dependent changes in internal cues produced by reward events and by the instrumental response. The control exercised by internal cues was shown to be associative rather than nonassociative, e.g., motivational. Similarities with, and implications for, conventional brightness differential conditioning were discussed.