Abstract
When a flashed target is presented close to a moving texture, the perceived position of the target is shifted in the direction of the motion following the flash (Whitney and Cavanagh, 2000). This effect is strongest when the target is superimposed on the motion and presented when the motion reverses direction (Anstis & Cavanagh, VSS 2011). Here we investigated whether visual motion can shift the perceived position of an auditory target and compared it to the shift induced in a visual target. A 32° x 22° field of white random dots moved horizontally at 40 degrees per second, reversing direction every 1500 ms. A burst of white noise was presented on two loudspeakers on the left and right of the monitor at the same time that the motion reversed direction. The apparent location of the noise burst was varied between approximately -16° and +16° from screen center by changing the inter-speaker delay. Six observers reported whether the sound was located to the left or right of screen center. We also tested the effect of the random dot motion on a visual target flashed synchronously with the motion reversal. For the visual target, consistent with previous literature, the perceived position of the flash was significantly shifted in the direction of the motion following the flash. However, for the auditory target there was no overall shift: 3 observers showed a null effect whereas the remaining 3 observers reported a significant shift of the auditory target in the direction opposite that was seen for the visual target (corrected for multiple independent tests). The difference between the direction of visual and auditory shifts was marginally significant. These results suggest that the effect of motion-induced position shift may operate differently in crossmodal space.
Meeting abstract presented at VSS 2013