Effects of angularity of the figures with sharp and round corners on visual evoked potentials

Following a study in which equilateral triangles elicited larger visual evo ked potentials (VEPs) than either squares or circles, we examined the effec t of single-line angular figures with a sharp or a round corner at angles o f 45 degrees, 90 degrees, 135 degrees or 180 degrees. VEPs were recorded mo nopolarly at four locations on the midline of scalp for 10 subjects, while the figure was tachiscopically presented to the lower visual field. Subtrac ted waves were obtained between figure and control (blank) conditions. N1 ( peak latency 135-142 ms) and P2 (235-237 ms) waves were identifiable. N1 am plitude tended to decrease as a function of angularity, irrespective of ori entation (angle pointing up or dawn). The effect of the sharpness/roundness of the corner was much smaller than that of its angularity These findings suggest that the greater VEP response with triangles than with squares and circles may be attributable to the acute angularity of triangles. Related c ortical processes and VEP components are also discussed.