On the Validity of Simulating Stagewise Development by Means of PDP Networks: Application of Catastrophe Analysis and an Experimental Test of Rule-Like Network Performance

This article addresses the ability of Parallel Distributed Processing (PDP) networks to generate stagewise cognitive development in accordance with Piaget's theory of cognitive epigenesis. We carried out a replication study of the simulation experiments by McClelland (1989) and McClelland and Jenkins (1991) in which a PDP network learns to solve balance scale problems. In objective tests motivated from catastrophe theory, a mathematical theory of transitions in epigenetical systems, no evidence for stage transitions in network performance was found. It is concluded that PDP networks lack the ability to recover the positive outcomes of analogous catastrophe analyses of real cognitive developmental data. In an attempt to further characterize the learning behaviour of PDP networks, we carried out a second simulation study using the discrimination-shift paradigm. The results thus obtained indicate that PDP learning is compatible with the learning of stimulus-response relationships, not with the acquisition of mediating rules such as conceived in (neo-)Piagetian theory. In closing, we speculate about the feasibility of simulating stagewise development with alternative network architectures.     

Block's Overflow Argument

This article challenges Block's ‘overflow argument’ for the conclusion that phenomenal consciousness and access‐consciousness are distinct. It shows that the data can be explained just as well (or better) in terms of a distinction between contents that are made globally accessible through bottom–up sensory stimulation and those that are sustained and made available in working memory through top‐down attention.     

Applicability of two violence risk assessment tools in a psychiatric prison hospital population

The risk of violent behavior is known to be higher for patients who suffer from a severe mental disorder. However, specific prediction tools for clinical work in prison psychiatry are lacking. In this single-center study, two violence risk assessment tools (Forensic Psychiatry and Violence Tool, “FoVOx,” and Mental Illness and Violence Tool, “OxMIV”) were applied to a prison hospital population with a primary psychotic or bipolar disorder and subsequently compared. The required information on all items of both tools was obtained retrospectively for a total of 339 patients by evaluation of available patient files. We obtained the median and inter-quartile range for both FoVOx and OxMIV, and their rank correlation coefficient along with 95% confidence intervals (CIs)—for the full cohort, as well as for cohort subgroups. The two risk assessment tools were strongly positively correlated (Spearman correlation = 0.83; 95% CI = 0.80–0.86). Such a high correlation was independent of nationality, country of origin, type of detention, schizophrenia-spectrum disorder, previous violent crime and alcohol use disorder, where correlations were above 0.8. A lower correlation was seen with patients who were 30 years old or more, married, with affective disorder and with self-harm behavior, and also in patients without aggressive behavior and without drug use disorder. Both risk assessment tools are applicable as an adjunct to clinical decision making in prison psychiatry.     

Predicting future blood donor returns: past behavior, intentions, and observer effects.

A prospective design was used to explore the efficacy of 6 factors (e.g., intentions) to predict the number of future blood donations in an initial sample of 630 blood donors. Differential predictions are made for the roles of past behavior and intentions with respect to occasional (4 or fewer previous blood donations) and regular (5 or more previous blood donations) blood donors. Intentions were predictive for occasional donors, and past behavior was predictive for regular donors. Furthermore, for regular donors only, an inverted U-shaped curve explained the relationship between past behavior and future behavior. Finally, it is reported that observing others fainting produces a reduction in the number of future donations for occasional donors. The theoretical and practical implications of these findings are discussed.     

The mechanics of reinforcement

Mathematical principles of reinforcement were developed in order to (1) account for the interaction of target responding and other behavior; (2) provide a simple graphical representation; (3) deal with measurement artifacts; and (4) permit a coherent transition from a statics to a dynamics of behavior. Rats and pigeons were trained to make a target response while general activity was measured with a stabilimeter. The course of behavioral change was represented as a trajectory through a two-dimensional behavior space. The trajectories rotated toward or away from the target dimension as the coupling between the target response and the incentive was varied. Higher rates of reinforcement expanded the trajectories; satiation and extinction contracted them. Concavity in some trajectories provided data for a dynamic generalization of the model.