The relation between proximity and brightness similarity in dot patterns

The Gestalt studies demonstrated the tendency to visually organize dots on the basis of similarity, proximity, and global properties such as closure, good continuation, and symmetry. The particular organization imposed on a collection of dots is thus determined by many factors, some local, some global. We discuss computational reasons for expecting the initial stages of grouping to be achieved by processes with purely local support. In the case of dot patterns, the expectation is that neighboring dots are grouped as a function of proximity and similarity of contrast, by processes that are independent of the overall organization and the various global factors. We describe experiments that suggest a purely local relationship between proximity and brightness similarity in perceptual grouping.     

Expectation and autokinesis

The reported direction of autokinesis for naive observers is not biased by gaze deviations of 22.5 deg of arc. However, instructions to expect either “inward” or “outward” movement produce reports of autokinetic movement that are progressively biased in the expected direction. Instructions to expect “more” or “less” movement resulted in a decrease in the reported duration of apparent movement for the “less” group but no change for the “more” group. Response bias is not considered to play a role in these results. The results are discussed in terms of fixational bias and selective attention mechanisms of autokinesis.     

Clinical, electroencephalographic and computer tomographic studies of children with West and Lennox-Gastaut syndrome

The results of clinical, electroencephalographic and repeated computed tomographic examination of 14 children suffering from epileptic seizures in connection with the West and Lennox-Gastaud syndrome are analyzed and compared. Computed tomography yields little information regarding the etiology of such forms of epilepsy. Distinct clinical and electroencephalographic findings were accompanied by normal computed tomographic results in a large proportion of the cases. To avoid misinterpretation of computed tomographic findings and consequent prognostic errors in these epileptic cases it is necessary to take possible side effects of ACTH and corticosteroid treatment into account. At the climax of hormone treatment computed tomography revealed imposing changes in the form of generalized atrophy in 10 of the 14 children examined. These receded completely upon termination of hormone treatment.     

Tests for stability in linear structural equation systems

Interpretations regarding the effects of exogenous and endogenous variables on endogenous variables in linear structural equation systems depend upon the convergence of a matrix power series. Convergence depends upon the eigenvalues of the structural coefficient matrix. The test for convergence developed by Jöreskog and Sörbom is shown to be only sufficient, not necessary and sufficient.     

A more powerful method for testing for agreement between a judge and a known standard

We assume that a judge's task is to categorize each ofN subjects into one ofr known classes. The design of primary interest is employed if the judge is presented withs groups, each containingr subjects, such that each group of sizer consists of exactly one subject of each of ther types. The probability distribution for the total number of correct choices is developed and used to test the null hypothesis that the judge is guessing in favor of the alternative that he or she is operating at a better than chance level. The power of the procedure is shown to be superior to two other procedures which appear in the literature.The authors are grateful for the suggestions of the referees and for computer funding provided by the Northeast Regional Data Center at the University of Florida.     

Two logit models for external analysis of preferences

A logit vector model and a logit ideal point model are presented for external analysis of paired comparison preference judgments aggregated over a homogeneous group. The logit vector model is hierarchically nested within the logit ideal point model so that statistical tests are available to distinguish between these two models. Generalized least squares estimation procedures are developed to account for heteroscedastic sampling error variances and specification error variances. Two numerical illustrations deal with judgments concerning employee compensation plans and preferences for salt and sugar in the brine of canned green beans.     

The generalization of the effects of a cognitive-behavioral treatment program for aggressive children

A cognitive-behavioral treatment program for aggressive children was assessed using 12 outcome measures classified into five categories which reflected a continuum of generalization of treatment effects. From a summer daycamp 41 children, ages 7 through 12, were selected based on aggressive behavior displayed during the first week of camp. They were randomly assigned to either a treatment group or a nontreatment control group. Treatment consisted of four weeks of coping-skills training using behavioral rehearsal and self-instruction training. Considering all 12 measures, treatment was found effective (F=2.90, p < .01). The most meaningful results included improved interpersonal problem-solving skills and a decrease in being disciplined for fighting. No changes were found, however, in physical or verbal aggression and in peer rating of aggression. Modest support for the effectiveness of these treatment procedures was identified, although caution is needed in considering their clinical utility. Further research and application appear justified.