Longitudinal Development of the Automatic Postural Response in Infants

In this longitudinal study, the development of automatic postural responses elicited during stance following perturbation of the support surface was investigated. Infants (N = 9) unable to stand without support were tested initially: follow-up tests were performed until the infants were able to stand and walk independently. Surface electromyographic recordings of leg and trunk muscle activity following a postural perturbation induced by a forward or backward translation of the support surface were made for each infant. Muscle onset latencies following the perturbation and the proportion of trials in which muscle activity was recorded were determined. First, infants activated appropriate muscles either in isolation or in pairs and then combined these muscles into functional synergies. Although activation of all three postural muscles was recorded in infants before they were able to stand and walk independently, the three-muscle response was not consistent in the youngest children. The proportion of trials eliciting muscle activity continued to increase (p <.O5) after infants began to walk independently, with postural muscle activity recorded in virtually every trial by late independent walking. Thus. the automatic postural response elicited during stance was shown to begin with activity in single or paired muscles, followed by activation of the postural muscles in functional synergies. These data illustrate the progressive development of an effective sensory-motor organization.     

Creativity in an Indigenous Afro-Arab Islamic Culture: The Case of Sudan

The present study attempted to appraise creativity in the indigenous Sudanese culture, which is formed by a complex integration and interaction of various social and cultural factors, mainly of African, Arab, and Islamic origin. More specifically, the study investigated the concept of creativity in a conformist culture, the problem of using Western tests and the problem of modernization. Also it attempted to find answers to some crucial questions: What is the scope available for creative expression in a tight sociocultural system? How could creativity coexist with conformity? What form of creativity can exist in the indigenous sociocultural system?     

Personality and Coping: Three Generations of Research

ABSTRACT This article introduces the Journal of Personality 's special issue on coping and personality. It first presents a historical overview of the psychological study of how people cope with stress and identifies three generations of theory and research: (a) the psychoanalysts and the ego development school, which tended to equate personality and coping strategies; (b) the transactional approach, which appeared in the 1960s and emphasized situational and cognitive influences on coping while downplaying the role of individual differences; and (c) the most recent, "third generation," whose work is represented in this special issue and focuses on the role of personality in coping while maintaining strong operational distinctions among coping, personality, appraisal, and adaptational outcomes. This introduction concludes with a discussion of unresolved conceptual and methodological issues and a brief orientation to the third-generation articles that follow in this special issue.     

Detecting a nonevent: Delayed presence-versus-absence discrimination in pigeons

Eight pigeons were trained on a delayed presence-versus-absence discrimination paradigm in which a sample stimulus was presented on some trials but not on others. If a sample was presented, then a response to one choice key produced food. If no sample was presented, a response to the other choice key produced food. The basic finding was that performance remained constant and well above 50% correct on no-sample trials as the retention interval increased, whereas performance dropped precipitously (to below 50% correct) on sample trials. In the second phase of the experiment, all of the trials were no-sample trials, and reinforcers were delivered probabilistically for one group of pigeons and according to time-based schedules for the other group. The exact reinforcement probabilities used in Phase 2 were those calculated to be in effect on no-sample trials in Phase 1 (according to a discrete-state model of performance). Subjects did not show exclusive preference for the richer alternative on no-sample trials in the first phase, but those in the probabilistic group developed near-exclusive preference for the richer alternative during the second phase. These data are inconsistent with the predictions of the discrete-state model, but are easily accommodated by an account based on signal detection theory, which also can be applied effectively to discrimination of event duration and the “subjective shortening” effect.     

INTERPERSONAL AFFECT AND PERFORMANCE APPRAISAL: A FIELD STUDY

Interpersonal affect has been found, in prior laboratory research, to be related to ratings of job performance. Such findings have been taken to mean that affect creates bias in ratings. The present study was conducted to determine if this relationship would hold up in a field setting. The present study was also designed to examine how structured diary-keeping, and the nature of the appraisal instrument, might be related to affect-appraisal relationships. The results for 85 raters, and 404 ratees, suggested that affect was significantly related to all ratings, but more strongly related to trait-like ratings than task/outcome-like ratings, and that having raters keep performance diaries actually increased the strength of the relationship between affect and ratings. We concluded that affect may not be a biasing influence on ratings, but may be a result of better subordinate performance. Results from an analysis of the diary content supported this conclusion. Implications for the role of affect on ratings and the nature of the relationship between past performance and interpersonal affect in field settings are discussed.     

Education and the unity of the person

Conclusion The deeper meaning of education, says Dewey in his Human Nature and Conduct (1922), which distinguishes the justly honored profession from that of mere trainer, is that a future new society of changed purposes and desires may be created by a deliberately humane treatment of the impulses of youth (p. 69). For Dewey, a truly humane education consists in an intelligent direction of native activities in the light of the possibilities and necessities of the social situation (p. 70). Student impulse and interest are not to be suppressed nor continually vented in unrestrained expression. In view of the plasticity of youth, there is little danger that allowing the role of student interest will lead away from important objectives of the curriculum.Education which respects the integrity of the student is a prerequisite of the kind of educated public suited for fuller participation in the democratic processes which properly direct and reconstruct our social life. The citizen appropriate for a democratic society is neither the dull conformist nor the superficial, gushing, non-conformist or sensualist. Individual impulse and initiative is neither to be damned up nor frivolously expressed. Meaningful participation and fuller social reconstruction require that we respect the social conditions for the possibility of knowledge and its growth, and this is more easily achieved, and more broadly appealing, when we speak of plans for the school environment. Respect for the cognitive and developmental needs of our own children and young people is fundamental to the self-respect of any viable society. Education could be philosophical praxis for a better world.     

Semilattice-based dualities

The paper discusses regularisation of dualities. A given duality between (concrete) categories, e.g. a variety of algebras and a category of representation spaces, is lifted to a duality between the respective categories of semilattice representations in the category of algebras and the category of spaces. In particular, this gives duality for the regularisation of an irregular variety that has a duality. If the type of the variety includes constants, then the regularisation depends critically on the location or absence of constants within the defining identities. The role of schizophrenic objects is discussed, and a number of applications are given. Among these applications are different forms of regularisation of Priestley, Stone and Pontryagin dualities.     

Individual and age-related differences in children’s working memory

The purpose of this study was to investigate the degree to which age-related and individual differences in children’s working memory (WM) are due to a general or task-specific capacity system. Experiment 1 correlated children’s (N=146; age range 5–19 years) verbal and visual-spatial working memory performance with various intelligence and achievement measures. The results supporting a general system were that (1) visual-spatial and verbal WM measures were significantly intercorrelated with and without age partialed out and (2) both verbal and visual-spatial WM measures were significantly correlated with diverse achievement and intelligence measures. Experiment 2 compared three age groups (N=192; 7-, 10-, and 13-year-olds) on working-memory performance tasks under initial, enhanced (cued), and maintenance conditions. The results supporting a general capacity system were that (1) age-related performance differences in WM were found on all conditions and not isolated to specific processes, (2) the maintenance measures (high-load condition) predicted the variance better in age-related performance than process measures, and (3) although individual differences in WM performance reflected two independent operations, these operations produced similar correlations to achievement within age groups. Overall, the results support a general capacity explanation of age-related and individual differences in children’s WM performance.     

Group aggregates and individual reliability: The case of verbal short-term memory

Two experiments examined the generalizability of the effects of word length and phonological similarity with visual and auditory presentation in immediate verbal serial ordered recall. In Experiment 1, data were collected from 251 adult volunteers drawn from a broad cross-section of the normal population. Word length and phonological similarity in both presentation modes significantly influenced the group means. However, 43% of the subjects failed to show at least one of the effects, and the likelihood that effects appeared was highly correlated with verbal memory span. In Experiment 2, 40 subjects of the original sample were retested, 20 of whom had failed to show one or more effects in Experiment 1. Whether or not an effect had appeared for individual subjects on the first test session was a poor predictor of whether the effect would appear on retest. Finally, an analysis of subject reports demonstrated that the patterns of experimental data could be accounted for in part by the strategies that subjects reported using, and the effect of strategy was independent of the effect of span. The implications of these findings for theories of verbal short-term memory are discussed.