Phonological and Orthographic Processing : One or Both Hemispheres ?

Laterality refers to the contention that the left and right hemisphere of the brain process information differently. Currently under debate is whether there is laterality of phonological and orthographic processing. Two experiments used a lexical decision task and a priming procedure along with a distractor to the left or right visual field to test laterality. Experiment I manipulated sound similarity between strings whereas Experiment II manipulated visual similarity between strings. Both experiments tested three hypotheses. First, primed letter strings would be faster and more accurate than non-primed letter strings. Second, both hemispheres would show priming. Third, the left hemisphere in Experiment I would show greater priming than the right hemisphere, whereas the right hemisphere in Experiment II would show greater priming than the left hemisphere.