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Hongjing Lu, Daniele Zavagno, Zili Liu; Perceived higher luminance in the glare effect does not give rise to a stronger afterimage. Journal of Vision 2002;2(7):364. doi: https://doi.org/10.1167/2.7.364.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The glare effect refers to the phenomenon that when a surface is surrounded by regions of outwardly decreasing luminance, it will be perceived as self-luminous (Zavagno, 1999). It is also perceived to be of higher luminance. We investigated whether such a stimulus also gives rise to a longer lasting afterimage, as a stimulus of higher luminance would.
Method: Two glare-effect stimuli and two controls were used. The first glare-effect stimulus was a cross figure — a white square surrounded by four squares, the luminance of each of the four decreases outwardly. The second stimulus was a white disk surrounded by an annulus of decreasing luminance in the radial direction. For the control stimuli, the direction of the luminance gradient was reversed. In each trial, a stimulus was presented against a gray background for either 8, 12, or 16 seconds. It was then replaced by an outline figure, which was either a square or a circle slightly smaller than the white square or disk of the stimulus just presented. When the dark afterimage disappeared within this outline figure, the subject pressed a button to record the lifetime.
Result: As expected, the longer the stimulus presentation, the longer its afterimage lasted (F(2,6)=11.22, p<0.01). However, the glare-effect stimuli did not give rise to longer lasting afterimages. In fact, the lifetime was slightly shorter (F(1,3)=10.91,p<0.05).
Conclusion: The glare effect, although perceived to be of higher luminance, does not register a longer lasting afterimage. This indicates that the percept involves higher mechanisms than those responsible for afterimages.
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