1990 年 8 巻 2 号 p. 69-82
MM, an early blind subject, received optical iridectomy on 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. The first task was the discrimination of a a red light from a green one, which were projected onto an opaque glass screen. In spite of taking 6 months, she failed to reach the criterion of successful discrimination. On the second task, she was presented with the colored patches (including achromatic ones) attached on a white paper. She preferred to touch the edge of a colored patch with her fingers, whenever she tried to discrimitate. With such tactual aid she gradually attained the ability to discriminate between two hues during a period of 13 months. On the third task, which lasted 11 months, she was asked to distinguish two colored patches through the matching-to-sample method, and reached the criterion level. In the final stage of this task, she began to match without touching directly the edge of a patch.