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. Author manuscript; available in PMC: 2023 Apr 1.
Published in final edited form as: Psychophysiology. 2022 Apr;59(4):e14035. doi: 10.1111/psyp.14035

FIGURE 11.

FIGURE 11

(a) Pupil diameter is linearly related to the pixel intensity (luminance) at fixation for scenes that are equivalent in pixel intensity and contrast (luminance) when full-field scenes are presented (inset) and eye movements allowed. (b) Pupil diameter is no longer linearly related to pixel intensity at fixation when scenes are presented in a matrix (5 × 5; inset) so that each fixation includes all luminance variations. In both (a) and (b) of Figure 11, each point is one scene and all scenes were pre-experimentally manipulated so that mean pixel intensity was 140 (8-bit grayscale stimulus) (courtesy M. Bradley)