Left-right and upper-lower visual field asymmetries for face matching, letter naming, and lexical decision.

The relation between left-right and upper-lower visual field (VF) asymmetries was examined for face matching, letter naming, and lexical decision. Stimuli were flashed in the VF quadrants. Face matching resulted in a lower left and upper right VF advantage. Letter-naming resulted in a distinct upper-right VF advantage. For lexical decision, no upper/lower asymmetries were found. Words were processed faster in the right than in the left VF, while nonwords were processed equally fast in both VFs. The results are discussed in terms of hypothesized structural connections of the lower versus upper visual field to dorsal versus ventral visual pathways and in terms of attentional mechanisms related to the processing of visual information in the VF quadrants.