Biological Motivation for Motion Saliency

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Biological Motivation for Motion Saliency

In biological vision, bottom-up saliency is achieved through center-surround mechanisms i.e. mechanisms tuned to detect stimuli that are distinct from stimuli in their surround. Extensive psychophysics experiments have shown that these mechanisms can be driven by a variety of features, including intensity, color, orientation or motion, and local feature contrast plays a predominant role in the perception of saliency. Nothdurft has shown that simple visual concepts, such as bars, can be very salient when viewed against a background of similar visual concepts that dier from them only in terms of low-level properties, such as color, orientation, or motion

Displays similar to those used in Nothdurft's psychophysics experiments designed to determine the role of feature contrast on judgments of motion saliency are show below. Subjects were shown a display of moving dots such as that depicted on the left. While all dots (whose motion is indicated, in the figure, by arrows) were subject to motion dierent from that of their immediate neighbors, three (referred to as the targets, and indicated by circles in the figure) had substantially larger motion contrast than the others. The targets could be in different configurations, two of which are shown in the figure: (left) all three targets moved in the same direction,(right) where one target moved in a direction dierent than that of the other two.

Video Display of the Nothdurft Psychophysics Experiment

While all dots (whose motion is indicated, in the figure, by arrows) were subject to motion dierent from that of their immediate neighbors, three (referred to as the targets, and indicated by circles in the figure) had substantially larger motion contrast than the others. The targets could be in different configurations, two of which are shown in the figure: (left) all three targets moved in the same direction,(right) where one target moved in a direction different than that of the other two.

In all cases, subjects reported the percept of pop-out of a moving triangle, with similar detection rates. These experiments showed that both motion saliency and the perceptual organization of the points into a triangle do not depend on absolute quantities, such as the direction of motion of the targets, how coherent their motion is, or the type of background motion. Instead, it suggests that both motion saliency and perceptual organization are related to measurements of local motion contrast.

Publications:
On the plausibility of the discriminant center-surround hypothesis for visual saliency
D. Gao, V. Mahadevan, and N. Vasconcelos.
Journal of Vision, 8(7):13, 1-18, 2008. [doi:10.1167/8.7.13.]

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Biological Motivation for Motion Saliency
In biological vision, bottom-up saliency is achieved through center-surround mechanisms i.e. mechanisms tuned to detect stimuli that are distinct from stimuli in their surround. Extensive psychophysics experiments have shown that these mechanisms can be driven by a variety of features, including intensity, color, orientation or motion, and local feature contrast plays a predominant role in the perception of saliency. Nothdurft has shown that simple visual concepts, such as bars, can be very salient when viewed against a background of similar visual concepts that dier from them only in terms of low-level properties, such as color, orientation, or motion Displays similar to those used in Nothdurft's psychophysics experiments designed to determine the role of feature contrast on judgments of motion saliency are show below. Subjects were shown a display of moving dots such as that depicted on the left. While all dots (whose motion is indicated, in the figure, by arrows) were subject to motion dierent from that of their immediate neighbors, three (referred to as the targets, and indicated by circles in the figure) had substantially larger motion contrast than the others. The targets could be in different configurations, two of which are shown in the figure: (left) all three targets moved in the same direction,(right) where one target moved in a direction dierent than that of the other two.
Video Display of the Nothdurft Psychophysics Experiment
While all dots (whose motion is indicated, in the figure, by arrows) were subject to motion dierent from that of their immediate neighbors, three (referred to as the targets, and indicated by circles in the figure) had substantially larger motion contrast than the others. The targets could be in different configurations, two of which are shown in the figure: (left) all three targets moved in the same direction,(right) where one target moved in a direction different than that of the other two. In all cases, subjects reported the percept of pop-out of a moving triangle, with similar detection rates. These experiments showed that both motion saliency and the perceptual organization of the points into a triangle do not depend on absolute quantities, such as the direction of motion of the targets, how coherent their motion is, or the type of background motion. Instead, it suggests that both motion saliency and perceptual organization are related to measurements of local motion contrast.
Publications:	On the plausibility of the discriminant center-surround hypothesis for visual saliency D. Gao, V. Mahadevan, and N. Vasconcelos. Journal of Vision, 8(7):13, 1-18, 2008. [doi:10.1167/8.7.13.]