Figure 3.

Correlation in the illusion magnitude. Each point represents the magnitudes of two illusions for one participant in one of the three conditions (monocular, dichoptic, binocular). Comparing the Ponzo illusion and the Ebbinghaus illusion (A), the illusion magnitudes were not correlated in strength for each separate condition (N = 6 or 5) or for all three conditions considered together (N = 18 or 15). Comparing the Ponzo illusion in the horizontal and the vertical design (B), the illusion magnitudes were correlated in strength for each separate condition (N = 5) and for all three conditions considered together (N = 15).