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Barbara Blakeslee, Mark McCourt; Filling-in versus multiscale filtering: Measuring the speed and magnitude of brightness induction as a function of distance from an inducing edge. Journal of Vision 2010;10(7):423. doi: 10.1167/10.7.423.
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Early investigations of the temporal properties of brightness induction using brightness matching found that induction was a sluggish process with temporal frequency cutoffs of 2-5 Hz (DeValois et al., 1986; Rossi & Paradiso, 1996). This led Rossi and Paradiso (1996) to propose that a relatively slow “filling-in” process was responsible for induced brightness. In contrast, Blakeslee and McCourt (2008), using a quadrature-phase motion technique, found that real and induced gratings showed similar temporal characteristics across wide variations in test field height and demonstrated that induction was observable at frequencies up to 25 Hz. Here we compare predictions of filling-in versus multiscale filtering mechanisms with data disclosing the phase (time) lag and magnitude of brightness induction as a function of distance from the test/inducing field edge. Narrow probe versions of the original quadrature-phase motion technique (Blakeslee & McCourt, 2008) and a quadrature-phase motion cancellation technique are used to measure the phase (time) lag and magnitude of induction, respectively. Both experiments employ a 0.0625 c/d sinusoidal inducing grating counterphasing at a temporal frequency of 4 Hz and a test field height of 3o. A 0.25o quadrature probe grating is added to the test field at seven locations relative to the test/inducing field edge. The psychophysical task in both experiments is a forced-choice “left” versus “right” motion judgment of the induced plus quad probe compound in the test field. The results show that the phase (time) lag of induction does not vary with distance from the test/inducing field edge, however, the magnitude of induction decreases with increasing distance. These results are inconsistent with an edge-dependent filling-in process of the type proposed by Rossi and Paradiso (1996) but are consistent with multiscale filtering by a finite set of filters such as that proposed by Blakeslee and McCourt (2008).
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