SHIFTING BEHAVIOR - AN ANALYSIS OF RESPONSE PATTERNS OF PARKINSON PATIENTS IN DISCRIMINATION-LEARNING

Parkinson patients often show decreased performance on what is general ly referred to as ''shift tasks.'' This does not necessarily imply tha t Parkinson patients have problems with shifting, since task performan ce reflects not only shifting but also other factors. Using a discrimi nation learning task, we analyzed response patterns to determine the d ecision rules used. As well, we varied the manner of problem alternati on (implicit versus explicit) and the type of problem alternation (ext radimensional versus intradimensional shifts). In accordance with the literature, we found that Parkinson patients needed more trials to sol ve the problems. However, the response patterns of the Parkinson patie nts and controls were practically the same. An important finding was t hat. Parkinson patients did not hold on longer to a rule, which was co rrect in a farmer problem, than controls did. Therefore, we concluded that Parkinson patients are able to shift from one decision rule to an other. (C) 1995 Academic Press, Inc.