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.     

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.     

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.     

Narrative unity and clinical judgment

Alasdair MacIntyre's recent thinking both about the concept of a practice and the existence of narrative unity in human life raises important questions about how we should view clinical medicine today. Is it possible for clinical medicine to pursue patient well-being in a society (allegedly) afflicted with what he calls ‘modernity’? Here it is argued that MacIntyre's pessimistic view of the individual in contemporary society makes his call for patient autonomy in the clinical setting pointless. Finally, recent work in gerontology is cited to make three points: first, MacIntyre's pessimism about us is too extreme; second, the concept of a ‘fictionalized’ personal history is closer to reality than either MacIntyre's notion of narrative unity or the ideas of his imagined opponent (Sartre); and finally, we should not expect clinical medicine to produce patient well-being, when this is understood narratively.