Reinforcing variability in adolescents with autism

Five adolescents with autism, 5 adult control participants, and 4 child controls received rewards for varying their sequences of responses while playing a computer game. In preceding and following phases, rewards were provided at approximately the same rate but were independent of variability. The most important finding was that, when reinforced, variability increased significantly in all groups. Reinforced variability could provide the necessary behavioral substrate for individuals with autism to learn new responses.     

Ipsilateral loudness adaptation over multiple intensity levels

Could monaural loudness adaptation be a simple artifact of psychophysical contrast? From adaptation data based on the Ipsilateral Comparison Paradigm (ICP), A. J. Dange, J. S. Warm, E. M. Weiler, and W. N. Dember (1993) concluded that loudness adaptation was not an artifact of psychophysical contrast, but their conclusion was dependent on results from one intensity. This study, involving multiple intensities, re-examined the issue of contrast versus adaptation and generally supported the conclusions of Dange et al. The results also showed an unexpected asymmetry of adaptation based on the direction of the referent modulation used with the ICP technique. Some implications are discussed.     

The treatment of relevant and irrelevant outgroups in minimal group situations with crossed categorizations

Among a sample of Belgian high school boys, the author attempted to determine on the basis of social identity theory (H. Tajfel & J. C. Turner, 1979) whether an outgroup's relevancy in intergroup comparisons influences the amount of intergroup discrimination. Relevancy was manipulated by the use of 2 trivial categorization dimensions that were orthogonally crossed. In 1 of the crossed categorization conditions, this procedure resulted in the formation of 4 groups, whereas in the 2nd condition, only 2 of these groups were effectively formed. Nevertheless, the participants in both conditions were instructed to evaluate 4 groups--either 4 actual groups (1st condition) or 2 actual and 2 hypothetical groups (2nd condition). In both conditions, the intergroup evaluations exhibited the same pattern--that is, they did not differentiate their ingroups from the partly overlapping groups but were clearly biased against the double outgroup.     

Environmental influences on perceptual and motor skills of children from immigrant Ethiopian families

The purpose of this study was to examine environmental influences on perceptual and motor skills of children from immigrant Ethiopian families in Israel in comparison with those of Israeli-born children. The subjects were divided into groups based on age (6- to 8-yr.-olds and 10- to 12-yr.-olds) and length of time in Israel. The results of this study show that the perceptual and motor performance of 6- to 8-yr.-old, less recent Ethiopian immigrants is similar to that of the recent Ethiopian immigrants of the same age. A difference exists between those two groups and the Israeli-born children of the same age. In the 10- to 12-yr.-old age group, there is a marked difference between the performance of the two groups of Ethiopian immigrants. The difference between the less recent immigrants and the Israeli-born children is smaller for most tasks; however, the less recent immigrants' performance is still poorer than that of the Israeli children. These results are compatible with those of other studies describing the difficulties encountered by children who had not studied in formal educational settings and those who have had that experience.     

Emotion, plasticity, context, and regulation: perspectives from affective neuroscience

The authors present an overview of the neural bases of emotion. They underscore the role of the prefrontal cortex (PFC) and amygdala in 2 broad approach- and withdrawal-related emotion systems. Components and measures of affective style are identified. Emphasis is given to affective chronometry and a role for the PFC in this process is proposed. Plasticity in the central circuitry of emotion is considered, and implications of data showing experience-induced changes in the hippocampus for understanding psychopathology and stress-related symptoms are discussed. Two key forms of affective plasticity are described--context and regulation. A role for the hippocampus in context-dependent normal and dysfunctional emotional responding is proposed. Finally, implications of these data for understanding the impact on neural circuitry of interventions to promote positive affect and on mechanisms that govern health and disease are considered.     

Measurement of psychosocial adjustment to breast cancer: a unidimensional or multidimensional construct?

Using data from a longitudinal study of Hoskins' 'Patterns of Adjustment to Breast Cancer among Women and their Partners', a conceptually derived multidimensional formulation of psychosocial adjustment was empirically tested. The Psychosocial Adjustment to Illness Scale was administered to both patients and partners at six times post-definitive surgery, i.e., 7-10 days, 30 days, 60 days, 90 days, 180 days, and one year. Extensive factor analytic studies were performed on data from the Psychosocial Adjustment to Illness Scale at four of the collection times when complete data sets were available for 128 patients and 121 partners. Results of the principal components analysis with varimax rotation were compared to factor analyses reported by the developers of the scale. The seven-factor matrix reported by Derogatis was not reproduced; instead, one factor was consistently identified at each of the four time periods as the best solution. Although items from all seven domains of the scale loaded on the single factor, items pertaining to psychological distress and role performance in the domestic and social environments were most prominent. These data support the need to validate empirically hypothesized separate dimensions of psychosocial adjustment to breast cancer in both patients and partners as proposed in a number of widely used tests.     

Task demands and representation in long-term repetition priming

The effects of task demands on the representation of letter strings in long-term repetition priming (LTRP) were explored in two lexical decision experiments. The stimuli in both experiments were words and nonwords, some presented horizontally and some vertically. The only difference between the two experiments was the response required by the participant. In Experiment 1, the participants pressed one of two buttons, indicating whether or not a given stimulus was a word. In Experiment 2, the participants pressed one of four buttons, indicating both the lexical status and the orientation of a given stimulus. The results were that in Experiment 1, LTRP was not disrupted by a change in stimulus orientation, whereas in Experiment 2 it was, suggesting that the nature of the stimulus representation utilized in LTRP is partially dependent on the demands of the task.     

A model of human performance on the traveling salesperson problem

A computational model is proposed of how humans solve the traveling salesperson problem (TSP). Tests of the model are reported, using human performance measures from a variety of 10-, 20-, 40-, and 60-node problems, a single 48-node problem, and a single 100-node problem. The model provided a range of solutions that approximated the range of human solutions and conformed closely to quantitative and qualitative characteristics of human performance. The minimum path lengths of subjects and model deviated by average absolute values of 0.0%, 0.9%, 2.4%, 1.4%, 3.5%, and 0.02% for the 10-, 20-, 40-, 48-, 60-, and 100-node problems, respectively. Because the model produces a range of solutions, rather than a single solution, it may find better solutions than some conventional heuristic algorithms for solving TSPs, and comparative results are reported that support this suggestion.     

Age-related differences in semantic priming: evidence from event-related brain potentials

Hasher and Zacks (1988) suggested that aging may affect processes involved in the inhibition of irrelevant information during language processing. Our experiment tested this hypothesis using the N400 event-related brain potential in a priming paradigm and assessed whether older subjects could benefit from the constraints of a sentence context. Twenty older (63 to 88 years) and 20 young (19 to 29 years) subjects read sentences and word pairs. Each final word varied on the degree of relatedness to the preceding context, with some being highly related (BC), moderately related (R), or unrelated (U). Younger subjects showed the expected N400 effect gradient (U > R > BC) in both the sentence and word-pair contexts, while older adults showed no discrimination between the conditions (U = R = BC) for the sentence and limited discrimination (U > BC) for the word pairs. These results support the inhibition-deficit hypothesis, whereby older adults fail to inhibit related items in working memory, and suggest that older adults do not benefit from the constraints of a sentence context.