Vection in a Large Screen Immersive Virtual Environment

The illusion of self motion perception, generally known as vection has been investigated from a psychological perspective since 1875. Vection can occur naturally when in a stationary vehicle and observing a moving, adjacent object such as when sitting in a train and observing an adjacent train begin to move. Studying vection can provide insights into how sensory information is integrated in the brain as well as a means to improve the design of existing applications such as driving simulations and entertainment park rides.Our aim is to examine the visual factors that affect the perception of illusory self motion in a large screen immersive virtual environment. Among the factors investigated are, the direction of movement, the vertical field of view and the attention of the observer.
In an initial study we investigated how the direction of motion specified by optic flow affects the perception of self motion. We also studied the effect the floor projection (which significantly increases the field of view in our current setup: See Figure 1) has on the effectiveness of the illusion. Twelve trajectories of motion, varying by motion direction, were presented to seated, stationary users and consisted of a random dot limited lifetime particle system. An additional condition evaluated a limited subset of these motion trajectories in a photorealistic environment (Virtual Tübingen ? see Figure 2) [1, 2].
In a second study we evaluated the effect of two visual attention tasks on the perception of linear vection. All participants experienced three conditions: baseline (no attention task), visual attention (react to viewing one particular target), and working memory (count a subset of specific targets) [3]. In all conditions the virtual environment consisted of a tunnel-like scene and participants fixated on the center of the screen while targets appeared moving on the ground floor (see Figure 1).
In the first set of experiments, lower vection onset times were reported for backward, downward, circular, and curvilinear motions than for forward, sideways, and upward motions. Also, in the photorealistic environment we found that linear vection was improved (lower onset time) with a floor projection while circular vection was not affected.
The attention task was found to have a significant effect on vection onset time with a decrease from a mean of 10.23 seconds (baseline condition) to a mean of 7.81seconds (working memory condition).
Future research will further investigate the effect of an individual?s attention on the illusory sensation of self-motion. We will do this by altering the cognitive load of an individual in systematic ways and determining the impact of this cognitive load on subjective ratings of vection.
Last updated: Friday, 05.10.2012