CONSISTENCY OF THE FIRST FIXATION WHEN VIEWING A STANDARD GEOMETRIC STIMULUS

Eye movements in response to presentation of a standard geometric figu re (Rey Complex Geometric Figure) were investigated in 33 normal subje cts. The figure was presented to each subject for 20 s, with instructi ons to remember as much detail as possible. Stimulus display was manag ed by special software that ensured all subjects were focused on the c entre of the monitor before presentation, thus controlling for the ini tial point of gaze. Subjects were instructed, after viewing the stimul us, to reproduce the figure to scale on a blank sheet of paper. Locati on of the first voluntary fixation during the viewing period was consi stently near the same feature in 80% of subjects (cohort I, n = 20). P atterns of eye movement during the remainder of the period, however, w ere found to vary widely among individuals. A complementary experiment using a second group of subjects (cohort LI, n = 13) was undertaken t o examine possible effects of brain function lateralisation on process ing a feature in the left hemi-field. No lateralisation effect was evi dent and consistent identification of the same feature in the first vo luntary fixation was confirmed for all subjects. No systematic relatio nships were found between eye movement indices obtained from real-time viewing of the Rey Figure and subsequent recall by drawing.