1985 年 5 巻 2 号 p. 795-802
The mental representative structure of hierarchically ordered semantic categories was explored with sixty-six aphasic patients and sixty normal adults by a word-verification task. Four words concerning living things and ten line-drawings depicting an object were prepared as stimuli. All possible pairings of each of the four words with each of the ten line-drawings were made to be verified. The subjects were required to judge whether a word was true or false with respect to a picture presented simultaneously. The results indicated that subjective category domains were more diffusive in aphasic patients than in normal adults, and that this alteration was exclusively due to increase of peripheral members, but not of central members. It was also revealed that normative category boundaries may be preserved unconsciously or “incompletely” in aphasic patients except the severe fluent subgroup, in whom there may be profound disintegration of boundaries. On the other hand, some common features concerning intra-categorical structure across normal adults and aphasic patients permit the hypothesis that aphasic patients may retain partially normal semantic knowledge.