Figure 1.

(A) Stereo half images presented to each eye shown in crossed disparity (with cross-eyed fusion). Subjects were instructed to maintain fixation on the center dot while the stimulus changed from a flat presentation to a stereoscopic corrugation. (B) Photorefractor calibration showing the slope of the brightness profile across the pupil as of function induced refractive error (+1.5 to −3D). Linear regression was used to define an individual calibration equation for each subject which was used to convert slope of the brightness profile to refractive error in the vertical meridian (accommodation). (C) Dynamic pupil and accommodation responses during uncrossed and crossed disparity demands. The raw accommodation (shown by filled circles) and pupil responses (shown by filled squares) were filtered to remove noise artifacts and the resulting smoothed profile is shown as a solid green and red line, respectively. The start and end coordinates of the two responses were identified using a velocity threshold criterion and the ratio of pupil change to accommodation was determined and compared. Note that the scales for two pupil plots for crossed and uncrossed disparity were offset, albeit with the same intervals, due to differences in starting pupil size for the example traces.