Effect of Cognitive Load in a Visual Search Task on the Perceived Threshold of Redirected Walking

Abstract

A new method of movement in Virtual Reality (VR) is redirected walking (RDW), which is implemented by manipulating the magnification of movement in VR in relation to the same movement in reality, such as taking two steps forward in the VR space when one step forward is taken in reality. RDW is implemented by manipulating the user's viewpoint in VR according to the magnification of the movement. However, if the manipulation is perceived, it causes discomfort. Therefore, the amount of manipulation of RDW is limited based on the user's perception threshold. Although RDW thresholds have been studied in previous research works, they might fluctuate depending on the cognitive load caused by different tasks in VR. Because tasks are rarely performed by walking alone in VR, RDW must be designed by considering the cognitive load in dual tasks. Therefore, in this study, we used a visual search task, which is an important task for humans, as a secondary task to quantitatively evaluate the relationship between the cognitive load (memory load and visual load) and the perceptual threshold in the visual search task, and to study the effect of cognitive load on the perception of RDW. The experimental results showed that the perceptual threshold of RDW increased when the memory load was increased. However, no change in the perceptual threshold of RDW was observed when the visual load was increased. This suggests that the memory load dominates the effect of visual search tasks on RDW and that the increased memory load increases the perceived threshold of RDW. In addition, the method of exploration can affect the perception of RDW because vestibular, visual, and somatosensory information differ depending on the way the body is moved during the visual exploration task.