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.     

Patterns of practice with the TAT in juvenile forensic settings

Psychologists in juvenile forensic psychological clinics were surveyed about usage of the TAT. A clear majority uses the TAT as part of their assessment battery, the majority using between six and ten cards. Administration and scoring methods were examined. Selection of cards was harmonious with prior research on theme productivity. Many respondents were found not to use the TAT because of time constraints, a finding discussed in terms of appropriate standards of care. Additional research needs to establish representative as well as expected standards of ethical practice for the TAT among general clinical groups, both adult and adolescent.     

Type A behavior pattern and the judgment of noncontingency: mediating roles of mood and perspective

Past research indicates that Type A's and B's differ in their behavioral responses to lack of control. The present study examined perceptual judgments of noncontingency in an attempt to clarify further the role of a control dynamic in Type A-B differences. Type A's and B's assumed the role of either an actor or an observer on a standard contingency judgment task. Consistent with previous research, both Type A's and B's exhibited an illusion of control when in the role of actor. Only Type B's exhibited an illusion of control when observing another person perform the task. Additional analyses indicated that the absence of an illusion of control by Type A observers reflected accuracy rather than a motivational distortion. Mood was also found to mediate control judgments, but only for actors. The plausibility of a memory-based interpretation for the mood effects is discussed.     

Three-way metric unfolding via alternating weighted least squares

Three-way unfolding was developed by DeSarbo (1978) and reported in DeSarbo and Carroll (1980, 1981) as a new model to accommodate the analysis of two-mode three-way data (e.g., nonsymmetric proximities for stimulus objects collected over time) and three-mode, three-way data (e.g., subjects rendering preference judgments for various stimuli in different usage occasions or situations). This paper presents a revised objective function and new algorithm which attempt to prevent the common type of degenerate solutions encountered in typical unfolding analysis. We begin with an introduction of the problem and a review of three-way unfolding. The three-way unfolding model, weighted objective function, and new algorithm are presented. Monte Carlo work via a fractional factorial experimental design is described investigating the effect of several data and model factors on overall algorithm performance. Finally, three applications of the methodology are reported illustrating the flexibility and robustness of the procedure.We wish to thank the editor and reviewers for their insightful comments.