Two experiments were conducted to investigate how kanjis were located in the memory structure of jukugo (two-kanji-compound word). In a previous study (Hirose, 1992b), it was suggested that the lexicon of jukugo was formed in such a structure that several jukugos containing a common first kanji were together, based on the first kanji. The present experiment was carried out using priming paradigms, as in the previous study, where the subjects were asked to make lexical decisions. Kanjis were divided into two types, independence words or combination words. The results showed that if an independence word was presented as prime stimulus, an activation to its jukugos was not observed. However, an activation was found if a combination word was presented as prime stimulus. Therefore it was inferred that the kanji as an independence word was memorized independently, whereas the kanji as a combination word was memorized in such a structure that was suggested in Hirose (1992b).
The effect of velocity gradients of the adapting stimulus to the resultant motion aftereffect in depth (MAE in depth) was examined. The motion vectors in the adapting stimulus all radiated from the origin (expansion). When the local speeds increase linearly towards periphery, the observers perceived the three-dimensional rigid motion. This three-dimensional rigidity perception was not occurred when the local speeds are zero at the periphery and increase towards center or when the local speeds are always the same. The duration and the percept of resultant MAE in depth were measured after adapting to the moving stimulus that have three types of velocity gradients described above. The duration of the MAE in depth was determined by the average speed of the adapting stimulus and had no relation to the percept of the adapting stimulus. A clear percept of three-dimensional rigidity arose in the resultant MAE in depth in all of the adapting stimulus. These results support the idea that looming detectors which selectively respond to the approaching motion have hierarchical structure to compute direction and velocity.
The characteristics of the visual and tactual activities were investigated in a congenitally blind person before and soon after an operation performed for regaining his sight. The subject was born blind due to congenital cataracts, and underwent aspiration of both cataractous lenses at the age of 9. Before the operation, his ERG was normal. After the operation he wore +12D lenses. The results obtained were as follows: (1) Before the operation, he could identify colors. To some extent, he could also count objects, discriminate the size of 2 two-dimensional rectangles or two circles. On the other hand, he could not identify two-dimensional figures. (2) During the 15 days after the second eye operation, his percentage of correct responses increased in all tasks, except for discrimination of the size of 2 two-dimensional circles. (3) Postoperatively, the patient no loger attempted to touch objects after counting them and discriminating the size of 2 two-dimensional rectangles, but with either size discrimination of the circular shapes or identification of shapes, he touched them after looking at them, just as before the operation.
Three pigeons were trained concurrently with both Pavlovian feature-positive and feature-negative discrimination tasks (A-, X→A+, B+, Y→B-), in which one diffuse feature stimulus (X) signaled that one target keylight (A) was followed by the food and another diffuse feature stimulus (Y) signaled that another target keylight (B) was not followed by the food. The birds learned both of these two discriminations and produced many pecks to the target keylight in both kinds of positive trials (X→A+ and B+) and few pecks to the target keylight in both kinds of negative trials (A- and Y→B-). In the test after this training, a temporal gap was inserted between the feature and the target, and its effects on the discriminations were investigated. The performance of the feature-positive discrimination was less susceptible to the effect of the gap than that of the feature-negative discrimination.