| Research Abstract |
In spite of partial loss of stimulus information, the vistual system can complete the loss and generate equivalent percepts to the case that complete information is given. In the present study, visual phantoms were intensively investigated as a representative phenomenon of such visual completion effects. The phantoms are perceived when a central portion of grating is covered up with an opaque occluder, connecting top and bottom section of the grating across the occluder. The phantom illusion is a unique phenomenon that has aspects of both modal completion and amodal completion, providing us with a good opportunity to investigate them together.
Kitaoka, Gyoba, ＆ Kawabata (1999) found that low-contrast inducing gratings can produce phantoms even in photopic vision when the occluder luminance is quite low or high. This new type of completion phenomena is called "photopic phantoms". Brown, Gyoba, ＆ May (in press) revealed that phantoms are generated with global figural fidelity to oblique i
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nducing grating, while the ordinal grating induction effect occurs depending on local luminance changes. Kawabata, Gyoba, Inoue, ＆ Ohtsubo (1999) clearly demonstrated that infants under 1 month of age can perceive the continuation of the grating behind the occluder, if the spatial frequency of the grating is low and the occluder height is narrow. Furthermore, Kawabata, Gyoba, Inoue, ＆ Ohtsubo (in press) showed that 4 month-old infants can perceive the grating continuation under broader occluders. However, they also found that there is a constraint between grating frequency and occluder height for perceiving grating continuation, and that the constraint is a common property for seeing the phantom illusion. When two objects overlap, the thicker one is perceived in front of the thinner one. This phenomenon is called Petter's effect. Kitaoka, Gyoba, Sakurai, ＆ Kawabata (in press) pointed out similarities between Petter's effect and the phantom illusion, which is visible when the spatial frequency is low or the occluder is thin.
As mentioned above, our phantom research provides a promising basis for building an integrative explanation of visual completion phenomena. Less
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