RECOGNITION IN THE DOMINANT AND NON-DOMINANT VISUAL HEMIFIELDS.

Abstract

As one experiment in a series demonstrating subliminal perceiving under a variety of conditions, stimuli (CVC trigrams) were exposed along the horizontal meridian at eight points subtending angles of 2, 6, 12, and 24 on the right and left visual hemifields. Recovery probabilities were calculated in each case. Previously, the 6 stimuli had been randomly ordered into pairs, and the pairings learned in a paired-associate task to a criterion of 120 correct serial anticipations. Recovery of the exposed stimuli ranged from chance to 100% according to angle of regard. The paired associate was sabstitated ar response for the exposed stimalus at 24 eccentricity to a significanc degree (# < .05). A standard finger aiming test was used to determine eye dominance for each of 20 Ss. The frequency of exposed stimi~li and paired-associate substitutes identified in the dominant hemifield were 102 and 54, respectively; for the non-dominant hemifield these were 66 and 75, respectively. Frequencies are for 6, 12O, and 24 angles combined. The ibalue, 20.3 (1 df), is highly significant (p < ,001 ). The superiority of word recognition to the right of fixation, which is well established, has been generally attributed to neural activity. Mishkin and Forgays (1752) propose selective training of the right visual hemifield. Hebb (1949) concludes that temporal-spacial networks are built up through reading, an integral part of which is activity in the frontal oculo-motor area of the cortex, present when S is reading from left to right. Presentation of a word to the right of fixation facilicates the activation of this network. Neural facilitation of the type described might be expected to be equally effective under the conditions of the present experiment. There was in fact better recognition in the right hemifield. This, however, could be an artifact of frequency of right dominance. When the data are corrected appropriately, right superiority, though still significanc, is reduced, while superiority of recognition on the dominant side is enhanced. The complementary finding, that the paired associate is substituted as response for the actual stimulus on the nondominant side, is of interest. No plausible explanation of this effect, however, can be suggested.