Salient visual objects perceptually disappear when they are surrounded by a rotating distracter (motion-induced blindness: MIB). In order to investigate the combined effects of perceptual grouping cues on the representation of an object with a hierarchical structure, we analysed the disappearance patterns of stimuli in which an inner target was embedded in an outer target. Participants were asked to report whether either or both of the targets disappeared during 60s of the MIB stimulus presentation. The results showed that when the targets were presented with a separation of less than 0.5 deg (high proximity), both targets disappeared simultaneously as a single object; however, they did not do so when the contour of the outer target was unclosed. Additionally, the results indicated that when both targets had high similarity in shape, the targets disappeared simultaneously, even when they were presented with a separation of more than 0.5 deg (low proximity). These results indicate that the visual system forms a whole object representation by utilizing multiple perceptual grouping cues in combination.（本研究では、内側の視覚刺激が外側の視覚刺激に囲まれている物体をターゲットとし、内側と外側ターゲット間の知覚的群化の程度が、運動誘発盲における視覚的消失にあたえる影響を検討した。その結果、ターゲット間の距離が、0.5度以下の場合に、内側と外側のターゲットは同時に消失しやすいことが明らかになった。一方で、ターゲット間の距離が、0.5度以下の場合で外側のターゲットの輪郭が開いている場合には、両ターゲットは別々に消失し、ターゲット間の距離が0.5度以上の場合では、両ターゲットの類似性が高い場合に同時に消失しやすいことが明らかとなった。）
Michiaki Shibata, Yousuke Kawachi, Jiro Gyoba.
