Abstract
A transparent kinetic dot object (KDO) appears to rotate in depth and has ambiguous rotation. A rotational aftereffect can be induced via bottom-up manipulations involving luminance, motion or disparity. Superimposing the KDO on a uniformly translating field of dots induces perception of the front surface of the KDO as rotating opposite to the translating field (Sereno & Sereno, 1999). Either a large disk or an annulus of translating dots is a sufficient inducing stimulus for a rotational aftereffect (Zotov, Grossmann & Dobbins, 2007). Here we explore rotational aftereffects via high-level inducers. A rotating Necker cube has ambiguous tilt and rotation, but the two are coupled. In an array of rotating Necker cubes all appear to have shared tilt rather than shared motion with a profound tilted-down or viewed-from-above bias (Dobbins & Grossmann, 2010). In the first experiment a rotating Necker array with shared tilt/rotation coupling is employed. The array's rotation sense is determined by the viewed-from-above constraint. The array is viewed for 20 seconds, followed by an ambiguously rotating KDO for 20 seconds. Observers exhibit a rotational aftereffect in which, upon its appearance, the KDO rotates oppositely to the inducer. Since the cubes are perspectiveless with balanced motion, the rotational aftereffect cannot be a bottom-up effect. In a second experiment, observers viewed a rotating KDO (ellipsoid) that cast a shadow on the floor. The rotating shadow induces the KDO to rotate consistently with the shadow's apparent rotation. When the shadow disappears, the KDO undergoes a rapid switch to the opposite sense of rotation. In control conditions in which the elliptic shadow deforms but is not consistent with rotation, there is neither rotational induction nor aftereffect. Because the shadow is remote from the object, we conclude that the rotational aftereffect is a high-level phenomenon of object-scene interpretation.
Meeting abstract presented at VSS 2018