Present study investigated how the spatial and temporal frequency, and the orientation contents of regions affect figure-ground organization. The results demonstrated that the regions with oblique gratings are dominantly perceived as figures and those with vertical or horizontal gratings are more likely to be seen as ground. These tendencies were found to appear only when the regions have relatively high spatial frequency. It is suggested that the visual channels which have fast response speed with low spatial resolution and coarse orientaion selectivity may be functionally related to ground analyses, and that those have slow speed with high resolution and fine selectivity may be to figure analyses.
Microgenetic process in subjective contour (SC) perception was studied under tachistoscopic presentation. Inducing figure (IF) was presented with duration of 10 - 300ms, and was followed by the exposure of masking pattern (dur.200ms). Subjects' task was to judge the appearances of both SC and IF. The results suggested that (i) SC perception required approximately 150ms exposure of IF, (ii) "alignment" figural cue could generate SC perception when each IF elements (sectors) were not clearly perceived, and "incompletion" cue could not operate efficiently.
An algorithm is proposed for generating subjective contours that are perceived in completely homogeneous regions. The algorithm is as follows : 1) detection of candidate points where subjective contours will pass, 2) determination of directions of possible subjective contours at each point, 3) determination of pairs of points to be filled in with subjective contours, 4) generation of subjective contours. Using this algorithm, subjective contours were successfully generated from several typical drawings. Furthermore, the algorithm was applied to synthetic line drawings where several polygons were overlapped one other without any visible inner contours. The algorithm could extract the inner contours and separate each component polygon.
Performance of motion direction discrimination was measured for one target(pt) and surround fields(ps) when each of the random dot fields was displaced indepencently. If Ps was displaced in the same direction of Pt by small displacements, the motion direction of Pt was percieved to be reversed. These optimum displacements increased with increasing the height of Pt. If Ps was displaced by the values greater than the displacements shown above, the all fields were percieved to move uniformly in the direction of Ps. These phenomena were discussed in relation to the visual motion processes.
Response characteristics of the smooth pursuit eye movement system(SPN system) were studied,using moving auditory stimuli. Although the gain is lover,the system shoved simple lowpass filter shaped characteristics similar to those observed when the system is tracking visual stinuli. Experinental results suggest that the SPN system is a feedforward system which stimulated by perceived motion,and not such that Whose tracking error is corrected by a feedback loop
Two experiments were planned to determine the adaptation effect on auditory perception. In the Experiment 1,the adaptation effect on the pitch perception was measure(L As a result, typical adaptation effects were found.In the Experiment 2, experiment on adaptation to the theoretically dissonant intervals were conducted in order to determine whether the increasing frequency of presentation of the " dissonant" intervals makes them perceptually consonant or not. The theoretically dissonant interval was presented to the subjects three time s as many as other intervals in the series stimuli. As the results of adaptation, the judged consonance of major 7th increased prominently in the course of session. Two modes of the modification were observed: (1) the selective increase in judgements of adapted interval ; and (2) the global shift over the judgements of the series stimuli.