Asymmetrical processing of tachistoscopic inputs in undergraduates across sex, handedness, field-side, and fixation instructions.

Past studies have indicated that men as well as right-handers show a right-visual field (RVF) advantage for letter recall and a left-visual field (LVF) advantage for letter position recall, suggesting asymmetrical brain organization for these groups. To examine these laterality effects more closely, 96 undergraduates were tested in a tachistoscopic task; they were equally divided by sex and hand dominance. On each of the 48 trials, subjects were required to recall either the letters or respective letter positions within 4 x 4 matrices flashed to the right or left visual field for 100 msec. Subjects further received instructions prior to each trial cueing them as to the field in which the matrix would be positioned (i.e., left, right or neither). Analyses indicated that right-handed men showed the predicted RVF advantage for letters while only right-handed subjects evidenced a LVF advantage for letter positions. Instructions might have contributed to the observed sex difference with letters; this would imply that right-handers exclusively possessed this asymmetrical organization.