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Michael Zenz, Rick Cai; The effect of metacontrast masking on the Fröhlich effect. Journal of Vision 2008;8(6):133. doi: 10.1167/8.6.133.
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© ARVO (1962-2015); The Authors (2016-present)
The onset of a moving object is often times perceived as being displaced forward in it's motion trajectory; this visual illusion is called the Fröhlich Effect. One explanation of this displacement states that the early portion of the motion trajectory is masked by the later, and thus the actual onset of the object is simply erased from conscious awareness (Kirschfield & Kammer, 1999). However, other studies have produced results inconsistent with this explanation (Müsseler & Aschersleben, 1998; Cai, 2003). Whether masking is actually present in the Fröhlich Effect has never been directly measured. We measured it in this study. In Experiment 1 we found that in order to be detected, a color marking the first frame of a moving bar had to be at a higher saturation level than that of an identical control flash. This indicates that the first frame of a moving bar is indeed susceptible to masking. In Experiment 2 the first frame of the moving bar either had fully saturated color, resulting in no masking, or desaturated color, resulting in full masking. Consistent with Cai (2003), the onset of the fully saturated bar was perceived to be displaced forward in it's motion trajectory; however, the desaturated bar exhibited an even larger displacement. In Experiment 3 we found, using a classic metacontrast masking paradigm (Breitmeyer & Ögmen, 2006), that a fully saturated colored circle (a marker) is only partially masked when spatially surrounded and temporally followed by an annulus, whereas a desaturated version of the circle is fully masked in the same situation. In sum, we found that masking is indeed present, and is likely to play a role in the Fröhlich Effect. Interestingly, we also found that masking cannot account for the whole Fröhlich effect. Thus, the Fröhlich effect is likely to result from multiple perceptual mechanisms.
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