Abstract
The length of a repeating, back-and-forth motion trajectory is underestimated by as much as 30% (Sinico et al., 2009). This effect has been attributed to path averaging within a window of about 100 ms. We tested whether path shortening also occurs for transformational apparent motion (TAM). This illusory motion occurs with the onset of a bar adjacent to a stationary square, causing the perception of a motion along the bar (Tse et al., 1998). If the bar is turned off, the bar appears to shrink back to its original form. This illusory motion allowed us to investigate whether observers perceive that the bar appears shorter when undergoing TAM. While maintaining central fixation, participants (N = 11) viewed a TAM display consisting of a square and a sudden onset and offset of an adjacent rectangle. The length of the rectangle, its location relative to the square, and its duration on screen were varied. The experiment also included real-motion control trials with incrementally growing and shrinking rectangles that resembled the reversing illusory motion perceived in the TAM display. Stimuli were either black on a gray background (first-order objects) or dynamic white noise on a static white-noise background (second-order objects). The real-motion control replicated the perceived shortening effect for both first-order and second-order bars. The effect was also observed for both first and second-order bars in the TAM display. This result indicates that a similar motion path averaging occurs for both real and illusory motion.
Meeting abstract presented at VSS 2018