Abstract
Patients with ideational apraxia (IA) who display impairment in the use of objects in test situations, sometimes show proper and effortless tool-use performance in everyday life. The purpose of this study was to examine the dissociation between the faulty use of objects under experimental conditions and their preserved performance in daily living. Tool-use performance in four patients with IA was observed and analyzed in various experimental settings. The patients were required to use a spoon in several experimental situations, from those where semantically relevant information about the spoon was omitted, to those where actual meals were served on plates together with a spoon as in a normal eating situation. All patients showed significantly better performance in the situations where abundant relevant information about the spoon, such as plates or food, was provided, while they showed severe IA in utilizing the spoon in isolation. These results indicated that tool use is possibly influenced by situations in which the tool is surrounded by information, and that IA could be influenced by a patient's situated cognition. The neuropsychological dissociation between tool use in experimental conditions and in everyday life has conventionally been regarded as “dissociation automatico-volontaire” according to the principle of Baillarger and Jackson, but situated cognition may be another important factor to explain the phenomenon.
