早期失明者の開眼手術後における信号系活動(3) : 光・視-信号系活動における図領域の探索活動と方向の弁別活動

抄録

MM, an early blind subject, received an optical iridectomy in her right eye at the age of 12. Preoperatively, her right eye had only light perception. Immediately after the operation, she could distinguish brightness, but not color. In order to improve her visionsign system activity, we planned to develop her visual discrimination between vertical and horizontal strips. On the first task, she was asked to distinguish through the matching-to-sample method, a black vertical strip from a horizontal one (7.5cm×1.0cm in size) attached to a white paper. Even after 5 months of training, she was unable to reach the criterion of successful discrimination. On the second task, she was presented with green strips (12.0cm×2.0cm in size) attached to a white paper, in addition to tactile samples aiding the discrimination task. Performance only improved, when the supplementary tactile sample was attached to the rear of the stimulus card. With such tactual aid she gradually attained the ability to discriminate between two directions over a period of 4 months. In the final stage of this task, it was observed that her activity of exploring the edge of the figure-area, and of tracing from one edge of the strip to the other, gradually became a systematic one. A theoretical implication concerning the changes in her exploratory activities is briefly discussed.