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.     

HIV infection--psychological coping and political reality

The authors warn against a trivialization of the AIDS problem and against the call for state control. Since sexuality is ultimately uncontrollable, they plead instead for the greater clarification of the conflicts which those who are infected with HIV and those who are not infected experience in dealing with each other. The continuing mystification of these conflicts would result in mutual jeopardy through acting-out.     

Group differences in intelligence and speed of information-processing

Three samples of different levels of mental ability, but each of average or above- average intelligence, were administered a battery of reaction time test which measure the speed with which persons can execute various elementary cognitive processes. Discriminant analyses revealed significant differences between the groups in reaction times and intraindividual standard deviations, and univariate analyses indicated that higher ability groups tended to obtain significantly faster mean reaction times and to show significantly less intraindividual variability than lower ability groups. Groups which differed the most in mental ability differed to the greatest extent on the more complex reaction time tests but this pattern was reversed for groups which were relatively close in mean IQ. Generally, the results support the hypothesis that speed- of-processing is an important factor unferlying intelligence, but a number of puzzling findings indicate the need for continued research in this area.     

Effects of neonatal forebrain noradrenaline depletion on recovery from brain damage: performance on a spatial navigation task as a function of age of surgery and postsurgical housing

The experiments examined the contributions of forebrain noradrenaline and environmental enrichment to recovery of place navigation ability in rats after hemidecortication in infancy or adulthood. Noradrenaline depletion did not affect recovery from neonatal hemidecortication, although the early hemidecortications did allow sparing of function relative to adult operates. Noradrenaline depletion also failed to attenuate the positive effects of enriched housing on otherwise normal rats. Noradrenaline depletion did retard recovery of adult hemidecorticate rats housed in standard laboratory cages, but it did not retard recovery of adult hemidecorticate rats housed in enriched environments. The results suggest that noradrenaline is importantly involved in enhancing recovery from brain damage when other sources of compensation (e.g., neonatal injury, enriched environment) are absent.     

Sex differences in the effects of gonadectomy on amphetamine-induced rotational behavior in rats

The effects of gonadectomy on amphetamine-induced rotational behavior were studied in male and female rats. Different systemic doses were used to produce equivalent brain concentrations of the drug in each group, thereby controlling for sex differences in the metabolism of amphetamine. Ovariectomy of female rats significantly attenuated amphetamine-induced rotation, whereas castration of males was without effect. The results support the idea that in females, the endogenous gonadal hormones facilitate functional activity in the mesostriatal dopamine system.     

Attitude and personality characteristics of older stutterers

Attitude and personality characteristics of 29 stutterers (19 male, 10 female) aged 52–82 yr were assessed using five questionnaires. Results indicate that, while the older stutterers score approximately the same as young adult stutterers on scales assessing approach and performance behaviors, the large majority of older stutterers perceive their stuttering as less handicapping than when they were young adults. Self-perceived personality characteristics of the older stutterers were similar to a group of older nonstutterers. While a few of the subjects had experienced some degree of success as a result of treatment later in life, the majority of the subjects did not currently desire treatment.     

Perspectives on individual-family-social network interrelations

The author focuses on the trend in the family therapy field toward an expanded view of families in the context of their social environments. Within this broader eco-system perspective attention is given to individual-family-social network interrelations with implications for the family therapist.An earlier version of this paper was presented at the American Association for Marriage and Family Therapy, Dallas, Texas, October 29, 1982. Appreciation is expressed to Alice Lynn for her comments and suggestions on an earlier draft of this paper. The author has also benefitted from discussions with Douglas Sprenkle on paradigms and contexts.     

Human interventions in a behavioural experiment for Asian Elephants (Elephas maximus)

Animal Cognition - Experiments are widely used to investigate the behaviour and cognition of animals. While the automation of experiments to avoid potential experimenter bias is sometimes possible,...