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Marjan Persuh; Priming with flash-lag illusion is percept-dependent. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1293.
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© ARVO (1962-2015); The Authors (2016-present)
In priming, a presentation of one stimulus, the prime, affects the processing of a subsequent stimulus, the target. An influential proposal suggests that response priming depends on physical characteristics of the stimulus. We tested this hypothesis using a well-characterized flash-lag illusion: when a static stimulus is briefly presented in alignment with a moving stimulus, it is perceived as lagging behind it. This illusion is especially well suited for testing the hypotheses about priming for the following reasons: (1) it is very robust, (2) a large body of literature suggests that it is a high-level cognitive illusion and (3) it shows a strong dissociation between physical and perceived location.
Twelve participants were recruited from The City University of New York and participated in the study after giving informed consent. To prime for location, two horizontal bars, moving downwards or upwards were presented at the center of the CRT monitor. A dot was then flashed between the bars. When bars were moving downwards, dot position was perceived above the bar and vice versa. Participants made speeded responses to targets, which followed primes and consisted of two static horizontal bars with dot positioned above or below them. If response priming is based on physical characteristics of the stimulus no priming would be expected because the dot in the prime stimulus was spatially aligned with the bars. To test whether the moving bars alone influence reaction times to targets, we included a control condition (no prime) in which only moving bars were presented.
Our data demonstrated strong location priming; there was no priming for moving bars alone (control). ANOVA revealed a significant prime presence and congruency interaction (p = .001), showing that the difference between incongruent (M = 454 ms, SEM = 22 ms) and congruent trials (M = 418 ms, SEM = 22 ms) was significant only when the prime was present. Priming effects in the absence of prime (control) were not significant.
Contrary to the influential model of response priming, our data show that location priming with flash-lag illusion depends on the percept, not the physical stimulus. Because flash-lag illusion is considered a high-level cognitive phenomenon, our data further suggest that visual system rapidly computes perceptual quality of the stimulus, which can affect even fast motor responses.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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