Attentional effects on Necker cube adaptation.

Abstract

Abstract If subjects adapt to an unambiguous version of a Necker cube, a subsequent ambiguous cube tends to be seen in the opposing perspective. The present experiment shows that this adaptation effect depends on whether the adapting cube is attended. During the adaptation phase, subjects saw two superimposed cubes of opposite perspective and different sizes and colors centered on fixation. Subjects detected color changes in line segments that defined either the small or large cube. The perception of the subsequent ambiguous cube depended on which of the adapting cubes was task relevant. This attentional effect showed a strong asymmetry. When subjects attended to the small adapting cube, an aftereffect appropriate to the perspective of the cube was found, but when the large adapting cube was attended, no aftereffect was present. This asymmetry may relate to constraints on the spatial distribution of attention.Resume Si les sujets s'adaptent a une version non ambigu d'un cube de Necker, ils ont tendance a voir le cube ambigu qui suit dans la perspective opposee. La presente experience montre que cet effet d'adaptation depend de l'attention que pre@tent les sujets au cube d'adaptation. Pendant la phase d'adaptation, les sujets ont vu deux cubes superposes qui etaient presentes dans des perspectives opposees et dont la taille et la couleur variaient; ces cubes etaient centres sur un point de fixation. Les sujets detectaient les changements de couleur dans les segments de ligne qui definissaient le petit cube ou le grand cube. La perception du cube ambigu subsequent etait fonction du cube d'adaptation qui se rapportait a la ta@che. Cet effet attentionnel se caracterisait par une forte asymetrie. Lorsque les sujets pre@taient attention au petit cube d'adaptation, un arriere - effet approprie a la perspective du cube se produisait, mais non dans le cas du grand cube. Cette asymetrie peut e@tre reliee aux contraintes qui interviennent dans la distribution spatiale de l'attention. Several studies indicate that attention can affect the perception of the Necker cube. Pelton and Solley (1968) and Hochberg and Peterson (1987) have shown that subjects can change the rate of reversals through instructions, while Kawabata (1986) reports that the interpretation of the cube depends on which local feature of the cube is attended. Shulman (1992) recently published results indicating that adaptation of the Schroder staircase, a reversible perspective figure, depends on whether the adapting staircase is attended. During the adaptation phase, subjects saw two superimposed unambiguous staircases in opposing perspective. Attention was directed to one or the other staircase by asking subjects to detect colour changes during the adaptation phase in the relevant staircase. Perception of the ambiguous test staircase depended on which of the adapting staircases was attended.Von Grunau, Wiggin and Reed(1984) have shown that perception of the Necker cube can be biased by prior adaptation to unambiguous cubes. Since much of the prior work on attention and reversible perspective figures has been conducted with the Necker cube, it seemed worthwhile to show that Shulman's results (1992) generalize to that figure.Experiment 1METHODSubjects12 naive observers participated in Experiment 1.Apparatus and StimuliStimuli were displayed on a colour monitor controlled by an Amiga 1000 microcomputer.A fixation cross was displayed at all times. The adapting and test stimuli are displayed in Figure 1. The adapting cube could be either large or small. When two adapting cubes were presented simultaneously, one was large, the other small, and the two cubes were superimposed and centered on a common fixation point. The cubes were made of different sizes and colours so they could be readily discriminated during blocks in which both were simultaneously presented. The length of each side of the small cube was 1.5 degrees, the large cube 4. …