Expanding and Contracting Optic-Flow Patterns and Vection

Abstract

When stationary observers view an optic-flow pattern, visually induced self-motion perception (vection) and a form of motion sickness known as simulator sickness (SS), can result. Previous results suggest that an expanding flow pattern leads to more SS than a contracting pattern. Sensory conflict, a possible cause of SS, may be more salient when an expanding optic-flow pattern is viewed. An experiment was conducted to test if a more salient sensory conflict accompanying expanding flow patterns might inhibit vection. Participants (n = 15) viewed a pattern of blue squares, either steadily expanded or contracted, on a large rear-projection screen. Vection onset and magnitude were measured for 30 s with a computer-interfaced slide device. Vection onset was significantly faster, and vection magnitude stronger, when a contracting pattern was viewed. We propose that our extensive experience with forward self-motion may form a neural expectancy (exposure-history) about the sensory inputs which typically accompany expanding flow. However, since backward self-motion is less common, there may be a weaker exposure-history for contracting flow, and as a result these patterns generate less salient sensory conflict and subsequently less vection.

Inhibition of vection by red

“…The average latency was approximately 11 sec for the W/R condition-considerably longer than the latencies for normal forward vection (e.g., 4-7 sec for the optical flow stimulus; Bubka et al, 2008). In the W/R condition, the average duration was approximately 70 sec, and the average magnitude was about 40.…”

“…To date, color is one of the stimulus attributes in vection induction that has rarely been tested. In almost all previous studies, achromatic stimuli were employed to induce vection-that is, white dots on a black background (e.g., Bubka, Bonato, & Palmisano, 2008) or achromatic gratings (e.g., Brandt et al, 1973). No published study has ever investigated the effect of color on vection, except for Bonato and Bubka (2006).…”

Stimulus Meanings Alter Illusory Self-motion (Vection) — Experimental Examination of the Train Illusion

“…For example, the latency of vection (i.e., the delay between the initial exposure to visual motion stimulation and vection induction) has been examined in a number of previous studies (e.g., circular vection, Kennedy et al, 1996). These have typically reported a latency of 4 to 12 s (e.g., linear vection, Bubka et al, 2008), which is considered to constitute the typical vection latency range. However, the 'latency' of vection is thought to be very short in the train illusion.…”

Stronger vection in junior high school children than in adults

“…Vection induction requires a “latency” period (Kennedy et al, 1995) that usually lasts about 4–12 s (e.g., Bubka et al, 2008). When subjectively stronger vection is obtained, the latency tends to be shorter.…”