Traditionally, it was believed that a necessary condition for vection was
the stimulation of peripheral vision through a wide FOV display. Andersen
and Braunstein [5] showed that ``central vection''
(vection as a result of stimulating only the central visual field with
angles as small as 7.5
) was possible. A similar non-dependence of
vection on peripheral vision was reported by Howard and Heckmann
[47]. Other research
[14,71,70] has suggested that a
critical issue in determining vection is the apparent relative motion
between the self and the perceived visual background.
Because vection is influenced by the visual background, and because foreground occlusions make a display appear to be the visual background, one would expect that a foreground occlusion would increase vection. Howard and Heckmann [47] make essentially this point. ``The configuration in which we obtained good centre-consistent vection, namely a moving scene seen at some distance through a window in a large stationary surround, is typical of situations in which the world is seen through the window of a moving vehicle. The fact that good vection may be obtained under these circumstances is a point to be borne in mind by those who wish to avoid the high cost of producing wide-field displays to induce convincing sensations of self-motion in aircraft simulators.''
Similarly, Mergner and Becker [67] reported that when
participants were exposed to a 30 by 30 vection stimulus
in central vision, the participants never reported vection when the limited
FOV was created by masking (blanking) part of the screen (by putting a box
with a small opening over the projection system). In contrast, when the
same FOV restriction was created by a mask worn on spectacles, the
participants did report vection. In the latter case, the participants felt
the vection to be qualitatively less cogent than with full-field stimuli;
however, their quantitative estimates were only slightly reduced.