Parallel distributed processing and neuropsychology: A neural network model of Wisconsin card sorting and verbal fluency

Neural networks can be used as a tool in the explanation of neuropsychological data. Using the Hebbian Learning Rule and other such principles as competition and modifiable interlevel feedback, researchers have successfully modeled a widely used neuropsychological test, the Wisconsin Card Sorting Test. One of these models is reviewed here and extended to a qualitative analysis of how verbal fluency might be modeled, which demonstrates the importance of accounting for the attentional components of both tests. Difficulties remain in programming sequential cognitive processes within a parallel distributed processing (PDP) framework and integrating exceedingly complex neuropsychological tests such as Proverbs. PDP neural network methodology offers neuropsychologists co-validation procedures within narrowly defined areas of reliability and validity.     

Developmental sequences in the age of onset of disruptive child behaviors

Retrospective and prospective reports of the onset of disruptive child behaviors were analyzed in a sample of clinic-referred boys. The younger boys (ages 7–9 years), compared with the older boys (ages 10–12 years), showed the highest level of disruptive behavior and, judging from mothers' reports, had the fastest progression of onsets from less serious to more serious problem behaviors. Despite some overlap, developmental sequences in problem behavior within the domains of hyperactivity/inattention, oppositional behavior, and conduct problems were similar across the two age groups. This was also the case for developmental sequences of overt or confrontive problem behaviors and covert or concealing conduct problems. Sequences of the onset of oppositional behavior and conduct problems were validated through prospective data, based on the information from mothers, teachers, and boys themselves. The implications of the findings are discussed for the formulation of developmental pathways of behavior and the analysis of causal factors.     

The changing face of visual persistence

In three experiments, the effect of target luminance on estimates of visual persistence was determined on a popular successive-field task. Even though the experiments differed from each other only in terms of minor changes in stimulus conditions, very different effects were obtained across the three experiments. The different findings were attributed to the often overlooked roles of masking and target degradation on tasks of persistence. Implications for the numerous contradictory findings in the persistence literature are discussed, and the current popularity of the successive-field task is questioned.     

PRODUCING GENERALIZED JOB INITIATIVE IN SEVERELY MENTALLY RETARDED SHELTERED WORKERS

The development of generalized job initiative was examined with three severely retarded men working in an industrial assembly area of a sheltered workshop. Interventions included discrimination training, role-play training, and self-monitoring. For each participant, training was applied sequentially to three sets of job initiative behaviors. Intensive training was required to establish the first set of job initiative behaviors; however, the second and third sets of job initiative behaviors were learned with only discrimination training. The discussion summarizes the findings and suggests research needed to develop more powerful learning-to-learn paradigms.     

Self-perceived and independently observed competence of young adolescents as a function of parental marital conflict and recent divorce

The self-perceived and independently observed cognitive and social competence of young adolescents as a function of parental conflict and recent divorce was investigated. Subjects were 40 young adolescents between the ages of 11 years 1 month and 15 years 1 month. A 2×2 factorial design was used, with the independent variables being parental marital status (married vs. recently divorced) and parental conflict (high vs. low). Dependent variables included the following measures of adolescent competence: adolescent-completed measures of self-perceived competence, teacher-completed measures, behavioral observations, and school grades. The results indicated that the level of parental conflict, rather than parental marital status, appears to be the critical variable associated with adolescents' independently observed levels of cognitive and social competence. In regard to adolescents' self-perceived levels of cognitive and social competence, parental marital status was found to be the critical variable. The implications of these findings are discussed.This research was supported by the William T. Grant Foundation and the University of Georgia's Institute for Behavioral Research.     

Of beasties and butterflies: Evidence for the stability and domain-specificity of individual differences in categorization

Previous research has failed to demonstrate unambiguously the relative stability across time and consistency across tasks of individual differences in categorization, or categorization breadth The present study of categorizing behavior in college students assesses breadth at each of four points in time over a six-week period Results are consistent with an interpretation of breadth as a highly stable individual difference variable, but one that is constrained by the nature of the stimulus sets employed High stability coefficients were observed for each of two redundant tasks In contrast, cross-task consistency indices were generally low Personality correlates of breadth were similarly weak and inconsistent Several variables are suggested that may attenuate the generality of categorization breadth The existence of multiple styles of categorization is discussed