Figure 4. Perceptual repetition enhancement of the within-block response.

A) Within-block changes in the shape of the BOLD response (±SEM) as reflected in the difference in amplitude between the first and second part of the response. Upward bars indicate that the second part of the response was relatively enhanced in the late compared with the early stage of a perceptually stable period; downward bars indicate suppression of the second part of the response. Perceptual repetition enhancement of the within-block response change was found in the parietal cortex, suggesting additional neural processing when there is memory of stable perceptual history. * p< 0.05 (t-test across participants). Abbreviations as in Figure 2A. B) Event-related BOLD responses for the anterior intraparietal sulcus (region AIPS) during binocular and 3D-motion rivalry (graphs are labeled with an icon of the corresponding stimulus), averaged over blocks in the early (= after a few repeats; dashed lines) and late (= after many repeats; solid lines) stage of a perceptually stable period (±SEM). For both types of rivalry, the first and second part of the within-block response had similar amplitudes in the early phase of a perceptually stable period, whereas in the late stage of a perceptually stable period the second part was larger in amplitude than the first part.