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Baingio Pinna, Lothar Spillmann; Apparent motion depending on luminance and hue variations. Journal of Vision 2002;2(7):383. doi: 10.1167/2.7.383.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To study apparent motion produced by luminance and hue variations. By alternately increasing and decreasing the luminance of a short radial line running parallel to another whose luminance is kept constant, the two lines appear to change their spatial position back and forth. For example, when pairs of lines are arranged such as to create two spoke wheels of different diameter, changing the luminance in counterphase will make the inner and outer wheels appear to rotate in opposite directions. The change in spatial position is also present when the hue of one of the radial lines is varied. Method: Two frames of the same spoke wheel pattern were presented with a change of luminance (or color) in one of the two parallel lines. The amplitude of the luminance change as well as line width and distance between the two parallel lines was varied. Twelve naive subjects participated in each experiment. Results: Very small variations in luminance are sufficient to create the impression of apparent motion, while increasing the luminance difference between the lines increased the strength of the effect. In comparison, increasing the spacing between the paired radial lines reduced the strength of apparent motion. By combining a luminance change with a change in width of one the lines perceived rotation could be enhanced, cancelled or reversed. When one line becomes brighter while the other becomes darker, illusory rotation could be obtained in one direction only. Hue variations affected the amplitude and direction of the apparent motion differently. Conclusion: Oscillating rotary apparent motion has been demonstrated by luminance variation of paired parallel lines arranged in the form of a spoke wheel. This apparent motion effect is different from stroboscopic motion as no change in stimulus position is involved.
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