Induced movement in the visual modality: An overview.

Abstract

Induced movement, illusory movement in a stationary stimulus resulting from adjoining movement, has received steady experimental investigation over the last 70 years or so. It is observed under different viewing conditions in a wide variety of displays that differ considerably in overall size and in form of inducing and induced stimuli. Explanations have been diverse, some being based on relations within the display and others invoking mediation by other aspects of the observer's perception. Probably, no one explanation can account for all forms of induced movement. Current knowledge about induced movement may have important implications for visual perception of object morion. Among possibly important factors is size of display, which can vary from two small spots (e.g., Carr & Hardy, 1920) to displays occupying most of the observer's visual field (e.g., Post, 1986).A second major purpose of this overview is to examine explanations for induced movement (Explanations section). Duncker's (1929Duncker's ( /1938 findings have had an important influence here, although many of his suggestions have subsequently been shown to require at least some modification. For example, his theory I thank J. Morss for reading an earlier version of this article, J. Ravey for translation, and two anonymous referees for helpful suggestions.

Effect of visual surrounding motion on body sway in a three-dimensional environment

“…Induced movement is most effectively elicited when induced and inducing stimuli are as close as possible in all three dimensions of space (adjacency principle: Gogel & Koslow, 1972;Gogel & MacCracken, 1979;Reinhardt-Rutland, 1988), whereas motion parallax increases with increasing distance between two objects. As a consequence, if the contradirectional sway observed in foreground fixation condition (Experiment 1) was elicited by induced movement of the foreground, it should be even greater and more consistent when the earth-fixed foreground is coplanar with the moving background than when the foreground and background are at 100 cm from each other.…”

“…A perceived movement of the fixated foreground induced by the moving background ("induced movement"; see Reinhardt-Rutland, 1988, for review) could also be responsible for the contradirectional sway observed by Bronstein and Buckwell (1997). Van Asten et al (1988) investigating visually induced body sway in the anteroposterior direction reported that when the central part of their linearly moving display was masked, anteroposterior sway was in the opposite direction of background motion (moving forward -backward) in 25% of the trials.…”

Relationship of induced motion and apparent straight-ahead shifts to optokinetic stimulus velocity

“…Copyright 1990 Psychonomic Society, Inc. -Rutland, 1988), it is unlikely that each of the proposed visual-vestibular causes of 1M operate under all conditions in which 1M is observed. Specifically, with small inducing stimuli, which are incapable of eliciting vection, it is unlikely that vection sensations contribute to 1M.…”

Basics of seeing motion

“…A number of stimulus variables can be identified that reduce or promote induced motion. For example, induced motion diminishes when the motion of the inducing pattern increases in speed (36) . Another critical condition for induced motion is that the frame that defines the background and the enclosed stimulus should be adjacent to one another, i.e.…”

“…In this case, however, a displacement of sound opposite to the direction of visual motion adaptation can be observed, suggesting a cross-modal, visual-auditory aftereffect (49) . Motion aftereffects can also be obtained from (and interact with) induced motion (36) . These and other findings (50) indicate the existence of several different motion aftereffects, depending upon the site at which adaptation effects occur.…”