Hemisphere differences in the recognition of closed and open class words

The distinction between closed and open class words--of interest in the first instance because of claims about the support of structural analysis during comprehension--has its reflection in word recognition. For normal speakers, performances over these types give evidence of the operation of separate recognition devices, while for agrammatic speakers, performance indicates no such separation. A study of recognition accuracy with tachistoscopic presentation lateralized to the visual hemifields suggests some parallel between left and right hemisphere processing and the contrast of normal and agrammatic speakers: with direct input restricted to the left hemisphere, the vocabulary types show different levels of accuracy; no such differences are evident with presentations to the right.