The influence of spatial orientation on the perceived path of visual saltatory motion

Visual saltation is the illusory mislocalization that occurs when multiple elements are rapidly presented to two peripheral locations; mislocalized elements appear to fill in the intermediate space. We investigated the influence of element orientation on the path of illusory saltatory motion. Experiment 1 showed that congruence in element orientation at the two locations (horizontal-horizontal or vertical-vertical) produced rectilinear saltation, while incongruent orientations (vertical-horizontal or horizontal-vertical) elicited curvilinear saltation consistent with rigid rotation around a common point. In curvilinear saltation, mislocalized elements were perceived with an intermediate orientation. Experiment 2 showed that the perceived shape of the motion path was directly dependent on the salience of orientation information. In Experiment 3, we showed that the circular path of curvilinear saltation (induced by orientation incongruence) is altered by background motion (wedge-shaped regions of inward and outward moving dots) that overlaps only with the inter-element space. An ellipsoid path, where the major axis corresponds to the mislocalized element overlapping with outward motion and the minor axis corresponds to the mislocalized element overlapping with inward motion, is produced. These findings reveal that the interpretation of visual saltation arises from high-level computations in which the percept is derived through an interaction of form and motion.