Ebbinghaus Illusions with Disc Figures: Effects of Contextual Size, Separation, and Lightness

Abstract

The Ebbinghaus illusion was produced using figures with four small or large contextual discs located either near or far from the central disc. For similar figures, the discs were either all black or all white; for dissimilar figures, black and white contextual and central discs were used in opposition. 48 observers, in equal numbers, were assigned to one of the four crossings of size and separation of the contextual discs and, using the converging method of limits, illusion magnitude scores for each Ebbinghaus configuration were obtained. The central disc appeared larger when bounded by small contextual discs and smaller when the contextual discs were more distant. Contrary to size contrast theory, uniformly colored discs did not generate greater illusions; instead, white central discs appeared larger than black ones regardless of contextual color. Collectively, the results indicated that contour interactions play a prominent role in producing the Ebbinghaus illusion.

The Ebbinghaus Illusion: New Contextual Effects and Theoretical Considerations

“…The overestimation of this central circle with only 4 small contextual circles replicates many studies that examined the two standard Ebbinghaus fi gures independently ( Ehrenstein & Hamada, 1995 ;Vuk & Podlesek, 2005 ;Jaeger, et al ., 2014 ). The reduction of this overestimation produced by adding contextual circles appears comparable to the reduction in overestimation created by extending the contours in the Ebbinghaus fi gures with large but incomplete contextual circles.…”

“…Thus, any stimulus manipulation that hinders comparisons between the central circle and contextual elements reduces size contrast and consequently the illusion. 3 However, a growing number of theorists ( Ehrenstein & Hamada, 1995 ;Rose & Bressan, 2002 ) have identifi ed shortcomings in size contrast theory and some ( Weintraub & Schneck, 1986 ;Jaeger & Grasso, 1993 ;Roberts, Harris, & Yates, 2005 ;Jaeger, Klahs, & Newton, 2014 ) contended that the Ebbinghaus illusion may be a variant of the Delboeuf fi gure ( Fig. 1 b).…”

Ensemble perception in depth: Correct size-distance rescaling of multiple objects before averaging.

“…This led Im and Chong (2009) to cautiously suggest that the mean size representation is computed from individually rescaled sizes. However, given the debated nature of rescaling under the Ebbinghaus illusion (Ehrenstein & Hamada, 1995; Jaeger, 1978; Jaeger, Klahs, & Newton, 2014; Roberts, Harris, & Yates, 2005; see Robinson, 1998, for review), it is difficult to say whether the results of Im and Chong (2009) are related to size constancy. In addition, as we will demonstrate below (see the rationale of Experiment 2), Im and Chong’s (2009) design does not sufficiently address the question of whether individual sizes are actually rescaled prior to averaging.…”

Anodal Occipital Transcranial Direct Current Stimulation Enhances Perceived Visual Size Illusions

“…Two cognitive mechanisms have been proposed to account for the production of the Ebbinghaus illusion. One is low-level contour interaction (Todorović & Jovanović, 2018;Jaeger & Klahs, 2015;Jaeger et al, 2014;Jaeger, 1978), which is linked to lateral interaction in the early processing stage (Sherman & Chouinard, 2016;Salva et al, 2013), and the other is high-level size contrast (de Fockert, Davidoff, Fagot, Parron, & Goldstein, 2007;Coren & Miller, 1974;Massaro & Anderson, 1971), which largely relies on feedback connections from higher to lower visual areas (King et al, 2017;Schwarzkopf, 2015). For the Ponzo illusion, feedback projections from higher visual areas to V1 have been suggested (Zeng et al, 2020;He et al, 2015;Fang et al, 2008).…”

“…Converging evidence suggests that the processing of visual size illusions relies on both early feedforward processing in V1 (Chen, Qiao, Wang, & Jiang, 2018;Nakashima & Sugita, 2018;Sherman & Chouinard, 2016;Jaeger & Klahs, 2015;Jaeger, Klahs, & Newton, 2014) and late feedback projections from higher visual cortex to V1 (King, Hodgekins, Chouinard, Chouinard, & Sperandio, 2017;Schmidt, Weber, & Haberkamp, 2016;Schwarzkopf, 2015;Sperandio & Chouinard, 2015;Weidner et al, 2014;Schwarzkopf et al, 2011). Whether occipital tDCS affects the early or late processing stage remains to be determined.…”