Abstract
We describe a visual illusion in which a stationary, flickering disc appears to move when presented simultaneously with other flickering discs. We refer to this effect as flicker-induced induced motion (FLIIM). FLIIM occurs regardless of whether the discs have soft or hard contours, but only when there is more than one flickering object. Across three experiments, we examined (1) the optimal flicker rate at which motion was seen, (2) the strength of the effect as a function of eccentricity, and (3) whether the effect was present when the flicker is an isoluminant color change. In all experiments, four discs were presented on the screen for 1 s. Three of the discs were displaced by a small amount in a random direction each frame, while the fourth remained stationary. Participants attempted to identify the stationary disc. In all experiments, discs alternated between black and white at rates of 2-14 Hz. In a control, 0 Hz condition, the discs did not change color, but three of the four still moved. The effect was stronger (detection of the stationary disc was worse) when the discs were presented in the periphery (Exp. 1), compared to when they were presented foveally (Exp. 2). FLIIM occurred equally strongly for black-white and isoluminant color changes (Exp. 3). Across both kinds of changes and eccentricities, accuracy was worst at a 2 Hz flicker rate and gradually improved up to 8-9 Hz, at which point it was similar to the control condition. The presence of a static, non-flickering fixation point suggests that the effect is not due to ambiguity in the frame of reference.
Meeting abstract presented at VSS 2018