Figure 1

mfPOP Stimulator and Five-Ring Ensemble of Stimuli. (A) Stimuli are presented on two LCD displays (i) in a stereoscopic arrangement. Two dichroic mirrors (ii) direct the stimuli to the two eyes. Objective lenses (iii) render the stimuli at optical infinity. LEDs (iv) provide infrared (IR) illumination of the eyes. IR video cameras (v) image the pupils. The host computer (vi) tracks the pupil diameters at 60 frames/s synchronous with the displays. Eye positions and blinks are also recorded, and real-time feedback regarding the tracking accuracy is presented to the operator. (B) The individual stimuli have smoothly blurred sides and so are dominated by spatial frequencies <2 cpd. The contours shown represent the 80% level of the luminance of each region. The 5 concentric rings (numbers) of stimulus regions are somewhat overlapping to reduce under-sampling of the visual field. There is no overlap across the vertical and horizontal meridians. The fixation cross was 1.6 degrees across and was presented within the central 2 degrees of the visual fields.