Article Figures & Data
Figures
- Figure 1.
Rotating Snakes, by A. Kitaoka. A static motion illusion in color (top) and grayscale (bottom) is shown.
- Figure 2.
Human observers indicated that all element pairs in the static motion illusion contribute to the illusory motion perception. A, A single trial of the blue/white stimulus. B, A single trial of the luminance version of the blue/white stimulus, in which the blue was replaced with dark gray. C, Results for colored element pairs. The dashed lines indicate the 95% confidence limits for random choices, for any individual subject. D, Results for grayscale element pairs. E, Results averaged over all subjects; mean ± SD.
- Figure 3.
Both V1 and MT cells show longer latency responses to lower-contrast stimuli. A, Average responses of a V1 cell in an alert macaque to at least 300 presentations of each of the four different grayscale bars, as indicated, flashed on an intermediate gray background for 27 ms in the receptive field of the cell. B, Average responses of an MT cell in an alert macaque to at least 300 presentations of each of the four bars, as indicated, flashed for 27 ms in the receptive field.
- Figure 4.
Direction-selective cells responded more strongly to static presentations of adjacent element pairs when the motion percept of a given element pair was congruent with the direction preference of the cell. A, Checked bars, Histograms of C.I.s of 20 weakly direction-selective V1 cells (D.I.s < 0.3) for the two same-contrast pairs averaged together (top; median, +0.005), for the two opposite-contrast pairs averaged together (middle; median, -0.0015), and for all four contrast pairs averaged together (bottom; median, -0.0037). Black bars, Histograms of C.I.s for 19 strongly direction-selective V1 cells (D.I.s >0.3) for the two same-contrast pairs averaged together (top; median, +0.06), for the two opposite-contrast pairs averaged together (middle; median, +0.03), and for all four contrast pairs averaged together (bottom; median, +0.06). B, Histograms of congruency indices (see Materials and Methods) for 20 MT cells for the two same-contrast pairs averaged together (top; median, +0.13), for the two opposite-contrast pairs averaged together (middle; median, +0.09), and for all four contrast pairs averaged together (bottom; median, +0.09).
Additional Files
Supplemental Material
Files in this Data Supplement:
- Supplementary Fig. 1 - Supplementary Figure 1 Histogram of the average difference in number of spikes for congruent minus anti-congruent responses, averaged over all four element pairs. Because responses were brief, corresponding spike rates would be much higher.
- Supplemental Movie 1 - Supplementary Video 1 This movie shows that simply flashing the illusion on the retina, with fixation maintained, induces the illusory motion. To experience the effect, maintain fixation on the black dot while the movie loops.
- Supplemental Movie 2 - Supplementary Video 2 This movie shows an example of the stimuli used in the psychophysical experiments. Element pairs from the illusion were repeated, each pair separated by a gray spacer. In sequential frames the gray spacers of a previous frame was replaced by the element pair, and the element pair of a previous frame was replaced by a gray spacer. Thus in a continuous cycle of frames there is no net motion, although there often is apparent motion, as in the illusion. To experience the effect, maintain fixation while the movie loops. Most people report an illusion of rightward motion.
