The number of filling lines and their spacing in the Oppel-Kundt figure were varied so that various modes of grouping could be generated by contour-proximity. The magnitude of illusion, that is, the overestimation of a filled extent relative to an un filled extent, was measured by the method of graded series. The results demonstrated that the illusion was strongly influenced by the number of groups of lines rather than simply by the number of lines themselves. It was also found that inhomogeneous spacing which caused ambiguous grouping had only little influence on the illusion. Our previous findings suggested that the retinal separation between adjacent contours was not important for determining the illusion. The present results support this conclusion by implying that the illusion is likely to originate at higher functional levels generating size constancy, figural segregation and the like.
This experiment using a straight alley with rats tested a prediction from Hulse's rule-encoding hypothesis concerning serial pattern learning when reward of elements was changed from food pellets (original training) to saccharin solution (transfer training). Initially, three basic groups learned the monotonic (M) pattern 14-7-3-1-0, the nonmonotonic (NM) pattern 14-1-3-7-0, or the random (R) pattern under food pellets. These patterns differ as to whether there is any single rule or not. Then half of each basic group learned either the three-element (10-1-0) or the six-element (15-10-6-3-1-0) monotonic patterns using saccharin solution. During transfer training, pattern tracking-anticipated running corresponded to differential amounts or reward-was better in the rats originally trained under the M pattern than those under NM or R patterns. However, positive transfer across training phases was weaker than that predicted from the hypothesis. The results indicate that the rule learning established under extended training could be biased by peripheral hedonic stimulation, such as the quality of reward.
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.
In this review some recent psychophysical studies concerning mechanisms for spatial localization of visual objects, especially those that relate to vernier hyper-acuity in both static and dynamic situations were surveyed and discussed. The viewpoint adopted was to regard the function of the early visual processing to be the local analysis of spatial frequency with localized filters. Three approaches were introduced and commented upon to explain vernier acuity, and the plausibilities of the respective approach were evaluated. Thus, vernier acuity may be understood by supposing a process of localizing visual edges, orientation selectivity and/or phase sensitivity of visual channels. Moreover it was pointed out that the spatio-temporal averaging of visual positions was essential in the case of dynamic vernier acuity, especially for detection of the temporal offset.
Thirty male Wistar rats, which were previously trained in a Skinner box with left and right lever press, were administered one of three conditions: escapable, yoked inescapable, and no shocks. Twenty-four hours after the treatment, the rats were tested in a Skinner box on the appetitive left-right single alternation discrimination task between two levers. Results showed that the rats pretreated with inescapable shock responded significantly less during an initial stage of the task than the subjects with escapable shock and the no shock controls; motivational deficit was found in the inescapable group. In a later stage, however, the rate of correct response in the inescapable group was significantly lower than those in the other groups despite no significant difference in the number of responses was found among the groups. The results indicates that exposure to uncontrollability produced associative deficits; associative retardation is the main factor of the effects of uncontrollable shock. The generality of associative factors in the learned helplessness effects is discussed in relation to other studies which employed different types of learning task.