Shock intensity and signaled avoidance responding

Five rats were submitted to a signaled free-operant avoidance contingency. Throughout the experiment, shock intensity was varied from 0.1 to 8.0 mA, with shock duration constant at 200 milleseconds. Results indicate: (a) an all-or-none effect of shock intensity on response and shock rates, on percentage of shocks avoided, and on frequency of occurrence of responding during the preshock stimulus; and (b) no systematic effect of shock intensity on stimulus control, measured either by the percentage of stimulus presentations accompanied by a response or by the percentage of responses that occurred during those preshock stimuli. Such results indicate that for each subject there is a minimum shock intensity necessary to establish and maintain avoidance responding; intensities higher than this minimum value have little or no effect on responding (with an upper limit for those strong intensities with a general disruptive effect on behavior).     

Point biserial correlation coefficient and its generalization

The problem of measuring the association between two characters, one quantitative and the other qualitative, is discussed. The formula for the large sample standard error of the point biserial correlation coefficient under general conditions is derived. The point multiserial correlation coefficient is introduced and some of its properties are examined. Tests of different hypotheses appropriate to these types of problems are formulated.I wish to pay my sincerest thanks to Dr. C. R. Rao, Dr. S. K. Mitra, and the reviewers for their valuable suggestions.     

Development of planning and its relation to other cognitive processes

The purpose of this study was to (a) delineate the course of development of children's planning skills during school years, (b) examine whether different levels of planning exist, and (c) explore the role of other cognitive processes as cognitive correlates of planning. The participants were 250 students, 50 from each of the five targeted grades (3, 5, 7, 9, and 11). They each completed a battery of planning, attention, and simultaneous and successive processing tasks. MANOVA indicated that the main effect of grade was significant, whereas gender had no significant effect on planning. Pairwise comparisons of performance means between grades indicated that developmental trajectories were not uniform across planning tasks. Correlation and regression analyses showed that the relationship between planning tasks and attention, and simultaneous and successive processing scores varied as a function of the planning task and the grade level. Furthermore, two planning factors were found and cluster analyses of variables indicated that one of the tasks, Crack-the-Code, may represent a different kind of planning than the other planning tasks used.     

Predictive validity of the Dutch PCL:YV for institutional disruptive behavior: findings from two samples of male adolescents in a juvenile justice treatment institution

The present prospective study examined the predictive validity of the Dutch version of the Psychopathy Check List: Youth Version for disruptive behavior in male adolescents during treatment. The study comprised two samples admitted to different secure treatment institutions in The Netherlands, Jongerenhuis Harreveld (n = 81) and Rentray (n = 66). Overall, the results demonstrate that psychopathy is a significant predictor of institutional disruptive behavior, and physical violence in particular. Furthermore, Hare's traditional Factor 2 was more strongly related to disruptive incidents than Factor 1. By using the recently proposed three- and four-factor models of psychopathy, insight into the pattern of associations between psychopathy dimensions and different types of disruptive behavior was obtained. The antisocial dimension of psychopathy appeared to be more strongly related to severe incidents than the lifestyle dimension. Regression analyses identified significant contributions of the antisocial and lifestyle dimensions to the prediction of incidents. The relatively small degree of variance explained underlines the importance of other risk factors to identify adolescents at risk of disruptive behavior during institutional treatment.     

Priming index of the Spanish word fragments from the Dasí, Soler,and Ruiz (2004) database

Word-fragment completion is a frequently used test in implicit memory research. A database of 196 Spanish fragments was recently published (Dasí, Soler, & Ruiz, 2004) in which the fragments were described for indices, such as difficulty, familiarity, frequency, number of meanings, and so on (www.psychonomic.org/archive). In this work, a new index, the priming index, is described for the same 196 fragments. This index is calculated for each fragment by subtracting the difficulty index (the proportion of correct completion when the fragment is not studied) from the proportion of correct completion when the fragment is studied, and it means the capacity of an item to be primed. In order to determine whether the new index performs well, we have replicated some important experimental effects, such as priming, frequency, and difficulty. We consider that this index can help researchers to better select stimuli for fragment-completion tasks.     

Prerogatives Without Restrictions?

Philosophical Studies -