Dispersion in models of categorical perception

A signal detection theory model of auditory discrimination with a nonlinear mapping from stimulus continuum to perceptual continuum can account for the enhanced discrimination at the category boundary found in categorical perception. Properties of this transformation are specified by a unimodal “dispersion function”. Furthermore, it is shown that a system consisting of two acoustic feature detectors with an associated decision function is also a dispersive system, which models categorical perception of a stimulus continuum as well as boundary shifts under adaptation. The effect of detector adaptation on discrimination is discussed in view of three different types of decision variable and different types of detector noise.     

Structure and development of behavior systems

Behavior systems are particular organizations of cognitive structures that are called behavior mechanisms: perceptual, central, and motor. Thus, behavior systems are defined here in structural terms and not in terms of their functional characteristics. In young animals, behavior mechanisms often develop independently of functional experience, though specific types of experience are usually necessary for integrated systems to develop. These concepts are illustrated here by the dust-bathing, feeding, aggressive, and sexual systems of the fowl, which are considered to be typical of behavior systems in other species. Aspects of neural development are examined and found to facilitate our understanding of a wide range of developmental phenomena, such as critical periods and irreversibility. Finally, various examples of classical conditioning and instrumental learning are analyzed in terms of the type of structures involved, and they are related to general developmental processes.     

Varieties of positive and negative priming

Numerous recent investigations have focused on a particular relation between the roles a stimulus plays in successive displays: when a stimulus ignored by a subject on one occasion is to be attended on a succeeding occasion, reaction time to that stimulus is slowed relative to a control condition. But this is but one possible case ofnegative priming. There are other ways in which negative priming might occur, and there are several varieties of positive priming as well. All these possibilities were explored in the present experiment.     

Disentangling Type A behavior: The roles of ambition,insensitivity, and anxiety

This study identified stable components of Type A behavior as usually defined, and examined their relationships with more traditional psychological constructs. Overall scores on the most popular Type A measure (a version of the Jenkins Activity Survey) were moderately associated with ambition but largely unrelated to measures of adjustment. An item analysis yielded subcomponents of Drivenness and Involvement. Drivenness was unrelated to ambition, but was positively related to anxiety and negatively related to interpersonal perceptiveness. Involvement was positively related to ambition and to interpersonal competence. It is suggested that the Jenkins Activity Survey measures a heterogeneous mixture of constructive commitment and self-defeating responses that clouds its psychological interpretation.     

Learning and generalization of piagetian tasks by mentally retarded students

70 mentally retarded students, successfully taught to conserve number and substance in the Piagetian sense, resisted attempts at extinction but were unable to generalize to other conservation tasks.     

Assessing interactional competencies: The early social-communication scales

Interactional competencies that develop in the first two years of life provide a foundation for all further social and communicative developments. Their normal acquisition, especially in the handicapped, can not be taken for granted. If delays in social-communicative development can be identified early in life and changes made in how the social environment interacts with the child, intervention may effectively facilitate social development. However, to accomplish this, both a model for describing and an instrument for assessing interactional competencies are needed. A recently developed set of scales, organized according to a cognitive-developmental framework and drawing upon recent research literature, is described in terms of its organization and content. Results that support the cognitive model underlying the set of scales are reported. The paper concludes with a consideration of potential criticisms that may apply to such a theoretically based instrument.     

The Temple-Wisconsin Cognitive Vulnerability to Depression Project: lifetime history of axis I psychopathology in individuals at high and low cognitive risk for depression

The authors tested the cognitive vulnerability hypotheses of depression with a retrospective behavioral high-risk design. Individuals without current Axis I diagnoses who exhibited either negative or positive cognitive styles were compared on lifetime prevalence of depressive and other disorders and the clinical parameters of depressive episodes. Consistent with predictions, cognitively high-risk participants had higher lifetime prevalence than low-risk participants of major and hopelessness depression and marginally higher prevalence of minor depression. These group differences were specific to depressive disorders. The high-risk group also had more severe depressions than the low-risk group, but not longer duration or earlier onset depressions. The risk group differences in prevalence of depressive disorders were not mediated by current depressive symptoms.