Vection Perception During Exposure to Visual Motion of Narrow Field of Views
Coskun Joe Dizmen, Richard H. Y. So · Rare & Special e-Zone (The Hong Kong University of Science and Technology) · 2015
Purpose: This paper reports the preliminary findings of perceived vection during exposure to visual motion of narrow field-of-views (1 degree (horizontal) x 47 degrees (vertical)). Background: Perception of vection (illusive perception of self-motion in the absence of body movement) when watching large visual moving fields has been the subject of many studies. However, little attention was given to the perception of vection when watching visual motion of small field of views. Johansson (1977) reported that subjects experienced vection for a falling (/rising) random dot pattern covering 1 degree (horizontal) and about 47 degrees (vertical) of the visual fields at each side of the subjects’ peripheral visual field. In Johansson's study, subjects were exposed to larger FOVs first, and then the FOV was reduced gradually (till 1 degree) for the subjects who reported vection. This might have biased the results because the subjects were trained to look for vection perception. Methods: We conducted an experiment to study the interaction effects among (i) the presence and absence of ceiling light; (ii) direction of the visual motion; (iii) holding a cardboard in front versus staring at an LED placed also in front of the subjects; and (iv) speed of the visual motion (4.6 to 24.6 degrees per second) on vection ratings (from 0 to 6) and vection onset time. The visual motion stimuli for all conditions were random dots of 1 degree (horizontally) and 47 degrees (vertically) on either side of the subjects. The dots were moving vertically either upward or downward. Results: The preliminary findings of the first 8 subjects are presented in this paper. Rated levels of vection during the lights-off conditions were significantly higher and the vection onset times were significantly shorter than those reported during lights-on conditions (p<0.05). The results of holding a cardboard (versus staring at an LED) was similar to the effects of lights off conditions. Both caused significantly stronger vection (p<0.05). Both upward and downward moving stimuli at all speeds caused vection among the subjects but there was no significant effect across different direction nor speeds. Conclusion: Perception of vection does not require a large moving visual field-of-view. Vection was reported when watching two narrow stripes of moving visual scenes. Significant effects of holding a cardboard or turning the lights off are interesting and will be discussed in the presentation. To substantiate the findings, more subjects will be recruited