Dynamic Glass Pattern


In 1969 Leon Glass created a Moire effect using an array of random dots. He superimposed the array on a copy of itself, rotated about the centre by a small amount. A global circular Moire pattern was apparent in the superimposed arrays, at least when the rotation angle was very small. These patterns have since become known as 'Glass' patterns.
Ross et al. (2000) created a series of such Glass patterns, each containing an entirely new array of dots. When the series of patterns was presented rapidly, as in this demonstration, observers reported apparent rotation even though there was no dot-to-dot correspondence between successive patterns which could form the basis for this apparent motion. Use the playback controls to pause the animation and confirm the lack of correspondence between frames.
This motion effect has been interpeted as support for the theory that 'motion streaks' influence motion processing. A motion streak is a trail of neural activity left behind fast-moving objects, which can be seen when viewing firework displays. These trails can be detected by orientation-selective cells in the cortex, and could be used by the visual system to aid motion processing. The dot pairs in the Glass pattern may simulate motion streaks, which bias the random direction signals created by the sequence of patterns in favour of the rotational direction that is consistent with the streak.
Burr, D. C., & Ross, J. (2002). Direct evidence that “speedlines” influence motion mechanisms. Journal of neuroscience, 22(19), 8661-8664.
Geisler, W. S. (1999) Motion streaks provide a spatial code for motion direction. Nature, 400, 65–69.
Glass, L. (1969). Moire effect from random dots. Nature, 223(5206), 578-580.
Ross, J., Badcock, D. R., & Hayes, A. (2000). Coherent global motion in the absence of coherent velocity signals. Current Biology, 10(11), 679-682.