|Budget Amount *help
¥8,400,000 (Direct Cost : ¥8,400,000)
Fiscal Year 2000 : ¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1999 : ¥2,700,000 (Direct Cost : ¥2,700,000)
Fiscal Year 1998 : ¥3,600,000 (Direct Cost : ¥3,600,000)
(1) To provide a standardized stimulus set for studies of shape perception and recognition, we have developed a database of nonsense closed contour shapes with their various psychological properties. In the development, we have considered the usefulness for psychological research, the common properties sharing with natural objects, and the availability of techniques of geometric analyses. Among the many nonsense shapes created for this study, one hundred shapes were selected for the analyses. We constructed psychological similarity spaces by a sorting task, and measured various psychological properties such as complexity and symmetry. We also conducted a task to measure associations of the nonsense shapes with known natural objects. The analyses of the relations between psychological properties such as similarity, complexity, and symmetry ; and geometric properties such as Fourier descriptors and roundedness revealed that correlation between complexity and roundedness, and the correspo
ndence between the psychological similarity space and the similarity space derived from Fourier descriptors. As for the association data, we proposed an association-spreading index, which is based on KL information and is able to measure the variability of associations, and showed the efficiency of the association-spreading index.
(2) We conducted psychological experiments on perception and memory of nonsense shapes. (a) Inconsistent with the previous theories on the effect of attention on partially occluded figures in a selective attention task with nonsense shapes, we have shown that the effects of attention in fact can be accounted for by the effect of symmetry of the figures. (b) We investigated the spatiotemporal properties of visual short-term memory using nonsense contour shapes. In a recognition task where participants need to store precise shape of objects and the number of convex parts was used as an index of the complexity of objects, the more an object had convex parts, the less the recognition performance was. Detailed analyses of the data suggest that objects were segmented by convex parts, and each convex part was perceived and stored in memory. (c) To investigate the mechanism of the occurrence of negative priming in a matching task of nonsense shapes, the difficulty of target selection was manipulated by the binocular depth of the stimuli. The results showed that the determinant of the occurrence of negative priming was not the interference between target and distracter shapes, but the interference between the standard and distracter shapes. Less