Fig. 2.

Visuocortical contrast responses across extensive luminance range (49.2–1278.6 cd/m²). Data are group-averaged (n = 7) blood oxygen level-dependent (BOLD) responses (mean %signal change) for 9 luminance levels and 6 contrast conditions, across early visual cortical regions (V1–V3), displayed with power function fits. The visuocortical response to a full-field “black” screen (1.2 cd/m²) is represented by a magenta circle. The adapter stimulus response, denoted by a gray diamond, is a predicted response using results of the group-level nonlinear fit estimate for the 4% contrast condition. Data are means ± SE across participants.