The effects of word length and emotionality on hemispheric contribution to lexical decision.

The effects of emotionality and length on lateralized lexical decision of abstract nouns were investigated in 41 normal and three commissurotomized subjects. Emotionality had the same effect in both visual fields: Emotional words were responded to more accurately than neutral words. Length had different effects in the two visual fields: The accuracy of lexical decisions in the left visual field was selectively higher for four-letter words and in the right visual field it was selectively lower for six-letter words. The latency of lexical decisions revealed equivalent length effects in both visual fields. Of the commissurotomy patients, only L.B.'s left hemisphere performed above chance and revealed a length effect. Length effects are interpreted to reflect a change from a parallel graphic analysis to a sequential parsing strategy when resources are limited. Such a change can occur for words or nonwords in either visual hemifield.