Mechanism of the figural aftereffects.

Ganz, Leo

doi:10.1037/h0022952

“…This confirms the similarity between the illusion and F AE TC functions reported by Ganz (1966b) and Pollack (1958), respectively, although our functions do not decline as rapidly as theirs. The control TC function shows no systematic or significant deviation from zero.…”

Section: Methodssupporting

confidence: 78%

“…which presumably is not present in illusions. Illusions and FAEs would also be accompanied by different patterns of eye movements (e.g., Ganz, 1966b). Finally, the tendency to overestimate large IFDs was different in FAE and illusion conditions.…”

Section: Discussionmentioning

confidence: 99%

“…1a are presented simultaneously, the T figure will appear displaced to the right relative to the comparison (C) figure. Ganz (1966b) has shown that this illusion is an inverted-U function of the interfigural distance (IFD), and is virtually identical to the F AE function produced by presenting the I before the T figure (pollack, 1958).Since this configuration is one of the few still explainable by Ganz's model, it is crucial to note an apparent discrepancy between the model's predictions and the illusion. According to the model, the T figure is displaced away from the area previously stimulated by the I figure and hence the T and C figures are not aligned.…”

mentioning

confidence: 92%

“…1a are presented simultaneously, the T figure will appear displaced to the right relative to the comparison (C) figure. Ganz (1966b) has shown that this illusion is an inverted-U function of the interfigural distance (IFD), and is virtually identical to the F AE function produced by presenting the I before the T figure (pollack, 1958).…”

mentioning

confidence: 99%

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Induction-, test-, and comparison-figure interactions under illusion and figural aftereffect conditions

Howard

¹

,

Evansf

²

,

McDonald

³

1973

Perception & Psychophysics

1

0

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Ganz (l966a, b) has argued that an induction figure will displace a test figure placed near it under both illusion and figural aftereffect conditions. The data from Experiments I and II show that most of the illusion produced by the figures studied by Ganz results from an interaction between the comparison and induction figures. The data from Experiment III suggest that both the test and comparison figures interact with the induction figure under figural aftereffect conditions. Although the induction-test figure interactions do not contradict Ganz's model, the induction-comparison figure interactions cannot be explained by it. The data also suggest that researchers should be extremely cautious in drawing conclusions about the processes underlying illusions and figural aftereffects unless they are confident that there is no interaction between the induction and comparison figures. Ganz's (1966a, b) model of illusions and figural aftereffects (F AEs) has been extensively criticized for its failure to explain many phenomena. According to the model, FAEs are simultaneous illusions in which the trace of the test (T) figure is displaced away from the afterimage of the induction (I) flgure.! Thus, illusions and FAEs should be comparable functions of most independent variables. Several authors (e.g., Pollack, 1967;Over, 1968;Wagner, 1968;Howard, 1971) have pointed out that this prediction is incorrect for the Mu e ll e r-Ly e r , concentric circles, and related configurations which appear to produce displacement of the T figure toward the I figure over a wide range of illusion conditions and displacement away under' comparable FAE conditions.There are a few stimulus configurations, however, for which the model apparently predicts similar illusion and FAE functions correctly. If the I and T figures shown in Fig. 1a are presented simultaneously, the T figure will appear displaced to the right relative to the comparison (C) figure. Ganz (1966b) has shown that this illusion is an inverted-U function of the interfigural distance (IFD), and is virtually identical to the F AE function produced by presenting the I before the T figure (pollack, 1958).Since this configuration is one of the few still explainable by Ganz's model, it is crucial to note an apparent discrepancy between the model's predictions and the illusion. According to the model, the T figure is displaced away from the area previously stimulated by the I figure and hence the T and C figures are not aligned. If the T figure is now moved so that it touches the I figure as in Fig. lb, the model predicts that the T figure should not be displaced and no illusion should occur. The first prediction is confirmed by the obvious fact that no gap appears between the I and T figures. Yet "This research was supported in part by grants to the first author from the Colgate Research Council and from the Sloan Foundation.t Now in the Department of Psychology, University of Massachusetts. Amherst. Massachusetts 01002.many Os report that the left edge of the C figure appears to the...

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“…Coren (1969) has shown that this source of distortion can account for some 15';( of the Poggendorff iIlusion. Bekesy (1967) and Ganz (1966) have presented evidence that suggests that lateral inhibition operating on converging or intersecting line elements adds to the magnitude of many illusions. Coren (1970) has shown that when possible sources of inhibitory interactions are removed.…”

mentioning

confidence: 99%