Abstract
When the visual system analyzes distributed patterns of sensory inputs, what features of those distributions does it use? It has been previously demonstrated that higher-order statistical moments of luminance distributions influence perception of static surfaces and textures. Here, we tested whether the brain also represents higher-order moments of dynamic stimuli. We constructed random dot kinematograms, where dots moved according to probability distributions that selectively differed in terms of their mean, variance, skewness, or kurtosis. When viewing these stimuli, human observers were sensitive to the mean direction of coherent motion and to the variance of dot displacement angles, but they were insensitive to skewness and kurtosis. Observer behavior accorded with a model of directional motion energy, suggesting that information about higher-order moments is discarded early in the visual processing hierarchy. These results demonstrate that use of higher-order moments is not a general property of visual perception.
Highlights
Perception emerges from the statistical analysis of sensory information (Helmholtz, 1867; Jazayeri & Movshon, 2006; Pouget, Dayan, & Zemel, 2000)
When viewing a collection of elements that move independently according to samples from a probability distribution, as in a random dot kinematogram, the visual system can extract a percept of coherent motion
We found that human observers could detect odd motion only when either the mean or variance of the motion distribution was manipulated; in contrast, they were insensitive to changes in skewness and kurtosis
Summary
Perception emerges from the statistical analysis of sensory information (Helmholtz, 1867; Jazayeri & Movshon, 2006; Pouget, Dayan, & Zemel, 2000). We perceive mean luminance as brightness, luminance variance over space as spatial contrast, and positively skewed luminance as “gloss” (Motoyoshi, Nishida, Sharan, & Adelson, 2007). It is largely unknown, whether higher-order moments convey meaningful information in other visual domains. One domain that lends itself well to experimentally measuring the influence of higher-order moments is visual motion. When viewing a collection of elements that move independently according to samples from a probability distribution, as in a random dot kinematogram, the visual system can extract a percept of coherent motion. We ask whether the higher-order moments of the motion distribution correspond to other percepts. Based on prior studies of static textures (Kingdom, Hayes, & Field, 2001; Motoyoshi et al, 2007; Okazawa, Tajima, & Komatsu, 2015; Portilla & Simoncelli, 2000), it might be expected that they would
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