Neural Basis for a Powerful Static Motion Illusion

Abstract

Most people see movement in Figure 1, although the image is static. Motion is seen from black 3 blue 3 white 3 yellow 3 black. Many hypotheses for the illusory motion have been proposed, although none have been tested physiologically. We found that the illusion works well even if it is achromatic: yellow is replaced with light gray, and blue is replaced with dark gray. We show that the critical feature for inducing illusory motion is the luminance relationship of the static elements. Illusory motion is seen from black 3 dark gray 3 white 3 light gray 3 black. In psychophysical experiments, we found that all four pairs of adjacent elements when presented alone each produced illusory motion consistent with the original illusion, a result not expected from any current models. We also show that direction-selective neurons in macaque visual cortex gave directional responses to the same static element pairs, also in a direction consistent with the illusory motion. This is the first demonstration of directional responses by single neurons to static displays and supports a model in which low-level, first-order motion detectors interpret contrast-dependent differences in response timing as motion. We demonstrate that this illusion is a static version of four-stroke apparent motion.

Microsaccades drive illusory motion in theEnigmaillusion

“…A nonmutually exclusive possibility is that microsaccades may displace after-images caused by the black and white stripes in the pattern and thus cause phi movement. Conway and coworkers (61,63) recently showed that pairs of stimuli of different contrasts can generate motion signals (i.e., phi movement) in directionally selective neurons of areas V1 and MT, and proposed that this neural mechanism may underlie the perception of another type of illusory motion from static patterns (61)(62)(63). Whatever neural circuit is responsible for the percept, the link between microsaccades and the generation of illusory motion signals has not been directly demonstrated until now.…”

Cats and Illusory Motion

“…This illusion is called the Rotating Snakes illusion and can be considered an optimized version of either the Fraser-Wilcox illusion (Fraser & Wilcox, 1979;Naor-Raz & Sekuler, 2000) or the peripheral drift illusion (Faubert & Herbert, 1999). Conway et al (2005) suggested that these responses occur in the neurons in MT (middle temporal) and Kuriki et al (2008) showed that in humans hMT+ (middle temporal complex) responds to this illusion. Moreover, Ashida et al (2012) showed evidence that V1 (primary visual cortex) -V4, V3A (V3 accessory), and MT+ are involved in this illusion.…”

Microsaccades and Blinks Trigger Illusory Rotation in the “Rotating Snakes” Illusion

“…1E) (Kitaoka, 2005). A grayscale version of the illusion is effective perceptually as well, and drives the responses of directionally selective visual neurons, so long as the luminance relationship between the patches is preserved (Conway et al, 2005).…”

“…The Rotating Snakes is a spatiotemporal illusion, in which both spatial layout and temporal stimulation-usually brought about by eye movements (Backus and Oruç, 2005;Conway et al, 2005;Murakami et al, 2006;Beer et al, 2008;Ashida et al, 2010)-are critical to the perception. The specific eye movements and neural mechanisms involved remain controversial, however.…”

“…One theory explaining the phenomenon is that contrastinduced latency differences in neural responses and/or neural adaptation trick the brain's motion detectors into responding to the stationary patches as if to actual motion (Faubert and Herbert, 1999;Backus and Oruç, 2005;Conway et al, 2005;Kitaoka, 2006). For instance, latency differences between higher-and lower-contrast patches may generate equivalent neuronal responses in areas V1 and MT to those induced by actual motion (Conway et al, 2005).…”