Local contrast and maintained generalization.

Pigeons received variable-interval reinforcement for key pecking during presentations of horizontal and vertical line-orientation stimuli, while pecks during five intermediate orientations were extinguished. Lowest peck rates were observed during presentations of negative stimuli adjacent to the positive orientations while peck rate during 45 degrees (the intermediate negative orientation) was relatively high, i.e., there were negative contrast shoulders. When peck rates were manipulated in the positive orientations, peck rate in neithboring orientations changed in the opposite direction. Contrast shoulders faded after prolonged training. A second type of contrast, local contrast, was correlated with similarity of preceding stimulus and different average peck rates during different stages of the discrimination process. The data suggest that sequential local contrast accompanying the formation of a discrimination contributes to the form of generalization gradients. Blough's model of stimulus control predicts the changes in gradient form described here, but may not accurately depict the underlying process responsible for gradient form.     

The empirical study of teenage work: A behavioral code for the assessment of adolescent job environments

Policy recommendations that adolescents supplement their experience in school with experience in the workplace have been made in the absence of objective data on the nature of most adolescents' activity on the job. This paper presents a coding system for chronicling a variety of microbehaviors in sequence, as they occur, in adolescent job environments. Three elements of each of approximately 100 behaviors performed by a targeted teenage worker are recorded by an on-site observer who enters appropriate code numbers into a portable event recorder: (1) the social context of the behavior; (2) the character of the behavior; and (3) the duration and concomitants of the behavior, when appropriate. Each of 97 working teenagers was observed continuously over a two hour period on the job. Interobserver agreement on the coding of worker behaviors and the social contexts in which they occurred averaged .86 and .97, respectively. In addition to its applicability in research on the effects of working on adolescent development, information obtained using the code can be helpful in the evaluation of youth employment programs, the vocational counseling of adolescents, and the validation of subjective worker reports of job attributes.     

Behavioural family therapy and the influence of a systems framework

A family approach using the techniques of behaviour modification, to a family presenting with problems of encopressis in a five-year-old boy, is described. The usefulness of taking a broader analysis of the context of the behaviours targeted for modification under the impact of systems theories is emphasized. A one-year follow-up after treatment demonstrated both symptomatic and family changes.     

Exercise, changes in aerobic capacity, and changes in self-perceptions: An experimental investigation

Subjects in an exercise training condition participated in a 10-week aerobic exercise class, whereas subjects in waiting-list control and independent control conditions did not. The results indicated that subjects in the training condition evidenced reliably greater improvements in physical fitness (aerobic capacity) and reported reliably greater improvements in their abilities and confidence in both the physical area (e.g., ability to run distances) and nonphysical area (e.g., frustration tolerance) than did subjects in the control conditions. On the other hand, improvements in physical fitness were not related to reported improvements in abilities and confidence. These findings are of interest because they indicate that some of the important personal changes that are associated with physical fitness training are not due to changes in fitness, but appear to be due to other factors (e.g., group participation and expectancies).     

Kanji reading by a prekindergarten language-disabled child: A pilot study

A , severely language-disabled boy was taught 250 words made up of one, two, three, or four Japanese/Chinese kanji. Many kanji words were learned and some ability to process these in simple sentences was observed. Acquisition of a word for meaning was not dependent on its visual complexity, but on the child's ability to grasp the meaning of the word. Results suggest that a whole-word method may facilitate very early reading acquisition and a possible neurophysiological correlate of this is proposed. Kanji or whole words may prove useful for language-handicapped individuals unable to process words phonetically.     

Sexual preference,feminism, and women's perceptions of their parents

In an attempt to clarify the relation between parental variables, sexual preference, and sex-role attitudes, three groups of women were studied: lesbian feminists, heterosexual feminists, and heterosexual traditional women. The women were asked about their perceptions of their parents when they were in high school. The groups differed more from each other with respect to their perceptions of their fathers than their mothers. The perceived attitudes of the father were much more important in differentiating lesbian feminists from heterosexuals than in differentiating heterosexual feminists from heterosexual traditionals. Both the heterosexual groups (feminist and traditionals) reported having a more affectionate and involved father who also encouraged them more in the expression of anger than the lesbian feminists reported. The results suggest women's father relationships must not be obscured in research and support Johnson's hypothesis that the father relationship is more central than the mother relationship in sex typing and especially in the specifically sexual aspects of sex typing.     

Contextual potentiation of acquired behavior after devaluing direct context-US associations

In two experiments, water-deprived rats were exposed to tone-footshock pairings in a particular conditioning context. In Experiment 1, the training parameters were selected on the basis of parametric pilot data so as not to produce direct associations between the conditioning context and footshock. Despite independent evidence of no appreciable direct association between the conditioning context and footshock, animals tested in the conditioning context exhibited more lick suppression to the tone than other animals tested with the tone outside of the conditioning context. Thus, the conditioning context potentiated suppression to the tone in the absence of appreciable fear of the conditioning context. In Experiment 2, training parameters were used that permitted the formation of direct associations between the conditioning context and footshock; however, for half the animals, these associations to the context were then extinguished. With the tone absent, a comparison of extinguished animals tested either in the conditioning context or outside the conditioning context detected no differences in suppression, demonstrating the effectiveness of the extinction manipulation. However, other animals also subjected to extinction of direct context-footshock associations displayed greater suppression to the tone within the conditioning context than comparable animals tested outside the context. Collectively the data indicate that the superior retention-test performance seen within the training context can arise both from the commonly assumed direct associations between the training context and the unconditioned stimulus and from the potentiation by the training context of the associations between the nominal conditioned stimulus and unconditioned stimulus.     

The effects of distributed training on retention of operant conditioning in human infants

Long-term retention of operant footkicking acquired in the mobile conjugate reinforcement paradigm was assessed as a function of the distribution of training time. In the first study, 3-month-old infants were trained for either one 18-min session or for two 9-min or three 6-min sessions separated by 24-hr intervals. All infants exhibited retention during a test administered immediately after training, but only those trained in a single session continued to perform the conditioned response during cued-recall tests 7 or 14 days later. Infants trained in three sessions showed no evidence of remembering the contingency even after a week. A warm-up decrement, seen in the day-to-day performance of infants in the distributed conditions, was eliminated in the second study by the interpolation of a nonreinforcement period at the outset of daily sessions. This procedure also enhanced long-term retention such that infants trained in three 6-min session now remembered the contingency for 14 days and did not differ from infants who had received a single 18-min session. Whether distributed training facilitates or impairs long-term retention appears to depend on the opportunity for infants to acquire a sufficient number (or kind) of effective retrieval cues during original learning.     

Discrimination and generalization by rats of temporal stimuli lasting for minutes

In three experiments, rats learned to respond differentially to reinforced and nonreinforced trials when the length of the intertrial interval (ITI) predicted the trial outcome (reinforcement or nonreinforcement). Rats in control groups, for whom the length of the ITI did not predict the outcome, did not show differential performance on nonreinforced and reinforced trials. Generalization gradients obtained following discrimination training were comparable to those obtained following discrimination training with other types of discriminative stimuli. That is, groups which had shown differential performance in discrimination training yielded generalization gradients with fastest speeds at the previously reinforced ITIs, slowest speeds at the previously nonreinforced ITIs, and intermediate speeds at ITIs of intermediate length. Control groups yielded flat gradients across all ITIs tested. These effects were shown for relative time discrimination (short time = reinforcement, long time = nonreinforcement, or the reverse) and also for an absolute time discrimination (long and short time = reinforcement, middle time = nonreinforcement or the reverse). This method was effective for time duration measured in minutes rather than seconds, as is more commonly the case.     

Dynamic processes in music perception

A schema-based theory of music perception that describes the dynamic interaction between the musical event and the listener’s knowledge of the underlying regularities in tonal music is proposed. Three properties of musical schema are evaluated in a recognition memory experiment: (1) The schema engages a subset of the abstract knowledge system that is determined by the predominant key of the musical sequence, (2) the schema evaluates both interval relations and the functions of the sounded elements within the established tonal framework, and (3) the schema interacts continuously with the musical event in time to process pitch information in its temporal context. Listeners are required to identify the serial position of a chord that is changed between two successive chord sequences that are otherwise identical. The experiment measures the magnitude and the temporal extent of the disruptive effect of including in the sequence an element outside the tonal framework. The results show temporally specific effects on memory for pitch relations consistent with the operation of a musical schema. Comparisons are made with schema-based theories applied in other perceptual and cognitive domains.