Induced self-motion in central vision.

Abstract

Previous research on visually induced self-motion found that stimulation of the central visual field (up to 30 degrees in diameter) results in perceived object motion while self-motion requires peripheral stimulation. In the present study, perceived self-motion was induced with a radially expanding pattern simulating observer motion through a space filled with dots, with visual angles of 7.5 degrees, 10.6 degrees, 15 degrees, and 21.2 degrees. Speed and texture density were also varied. The duration of reported self-motion (a) decreased with increased speed, (b) failed to increase with increased visual angle, and (c) decreased with visual angle at the highest speed level. In a second experiment, subjects rated the perceived depth of the displays. The speed and speed/area interaction effects on judged depth matched those found for induced self-motion. These results suggest an extension of the focal/ambient theory: In addition to a more primitive ambient processing mode that requires peripheral vision, there is a higher level system concerned with ambient processing that functions in the central visual field and uses more complex stimulus information, such as internal depth represented in a radially expanding pattern.

Spatiotemporal boundaries of linear vection

“…Moreover, we have shown that perceived direction of curvilinear vection is not always reported unambiguously (Sauvan & Bonnet, 1989). These results suggest that the lower and the higher level ambient systems, according to Andersen and Braunstein's (1985) theory, should be involved in the perception oflinear vection.…”

“…Consequently, the receptive field size of the motion detector units that are stimulated seems to be essential for perceiving linear vection in the same way as are the size of the stimulus, its eccentricity, and the optical flow structure (Sauvan & Bonnet, 1993). According to Andersen and Braunstein (1985), two systems control ambient vision: a lower level system that would require peripheral vision, and a higher level system that would work in the central visual field and would process complex visual information such as depth cues. The more primitive ambient system has also been described as complementary to the focal system: The former would be involved in spatial orientation and localization; the latter, in object recognition (Wolpert, 1990).…”

“…Indeed, a rectilinear vection is perceived when a radially expanding dot pattern subtending 7.so of visual angle is the inducing stimulus (Andersen & Braunstein, 1985). Moreover, circular vection can be induced by stimulating only the central visual field, and not the peripheral field (Post, 1988).…”

“…Vection can also be induced, for example, by using both visual and vestibular stimulations (Dichgans & Brandt, 1978). It has been shown that central rectilinear- (Andersen & Braunstein, 1985), or horizontal linear- (Telford, Spratley, & Frost, 1992) vection is influenced by depth cues-that is, by complex visual information. For example, apparent depth, introduced by using kinetic occlusion information, influences the strength of horizontal linear vection (Telford et aI., 1992).…”

“…These results reinforce the proposal that the higher level ambient system, which may process visual information such as depth cues (cf. Andersen & Braunstein, 1985), is involved in the perception of complex induced self-motion (Sauvan & Bonnet, 1993). This we define as observer's (or robot) motions along linear and/or curved paths, especially in a cluttered environment.…”