Attentional modulation of self-motion perception.

Attentional effects on self-motion perception (vection) were examined by using a large display in which vertical stripes containing upward or downward moving dots were interleaved to balance the total motion energy for the two directions. The dots moving in the same direction had the same colour, and subjects were asked to attend to one of the two colours. Vection was perceived in the direction opposite to that of non-attended motion. This indicates that non-attended visual motion dominates vection. The attentional effect was then compared with effects of relative depth. Clear attentional effects were again found when there was no relative depth between dots moving in opposite directions, but the effect of depth was much stronger for stimuli with a relative depth. Vection was mainly determined by motion in the far depth plane, although some attentional effects were evident even in this case. These results indicate that attentional modulation for vection exists, but that it is overridden when there is a relative depth between the two motion components.