Left hemisphere superiority for pronounceable nonwords, but not for unpronounceable letter strings

Abstract

Right-handed adults were asked to identify bilaterally presented linguistic stimuli under three experimental conditions. In Condition A, stimuli were three-letter pronounceable nonwords (such as TUP), and subjects were asked to report them by naming them. In Condition B, stimuli were three-letter pronounceable nonwords, and subjects were asked to report them as strings of letters. In Condition C, stimuli were more or less unpronounceable letter strings (such as UTP) created by rearranging the letters of pronounceable nonwords, and subjects reported them as strings of letters. Pronounceable nonwords were found to be better identified from the right visual hemifield irrespective of the way in which they were reported. Unpronounceable letter strings did not produce any visual hemifield difference. Nonwords are of interest because they can be seen as potential words that lack both specific semantic properties and entries in the subject's internal lexicon. The results of the experiment are consistent with the view that both the left and right cerebral hemispheres are able to identify letters but the left hemisphere is more sensitive to the pronounceability of the nonwords. This may happen either because the left hemisphere can make better use of resemblances to real words or because it has access to spelling to sound correspondence rules.