The role of verbal labels in the judgment of orientation and location

In an earlier study it was found that judgments of right-left orientations and locations were more difficult than judgments of up-down only when spatial words were used in the tasks. Experiments are reported in which pictures of many objects were presented to eliminate the possibility that subjects in previous studies had used strategies specific to single-stimulus tasks. In experiment 1, right-left orientations were judged more slowly than up-down orientations both when the spatial words were used and when arbitrary letters replaced the spatial words. In experiment 2, judgments of the right-left locations of pictures took longer than judgments of their up-down locations only when spatial words were used in the task; the right-left difficulty was eliminated when arbitrary letters replaced the words. The differential effect of words and letters in location judgments seems to be due to the different coding strategies adopted by subjects under the two conditions. It is concluded that a right-left difficulty does not depend on the use of spatial terms: word and letter conditions yield different results only when the task permits different judgments to be made under the two conditions.     

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 evoked potentials (VEPs) than either squares or circles, we examined the effect of single-line angular figures with a sharp or a round corner at angles of 45°, 90°, 135° or 180°. VEPs were recorded monopolarly at four locations on the midline of scalp for 10 subjects, while the figure was tachiscopically presented to the lower visual field. Subtracted waves were obtained between figure and control (blank) conditions. N1 (peak latency 135–142 ms) and P2 (235–237 ms) waves were identifiable. N1 amplitude tended to decrease as a function of angularity, irrespective of orientation (angle pointing up or down). 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 cortical processes and VEP components are also discussed.