Hemisphere-specific effects in word recognition do not require hemisphere-specific modes of access

Consistent with converging experimental evidence, we assume that foveal information is initially split across the two cerebral hemispheres. We have previously presented the SERIOL model of letter-position coding, which specifies how the resulting two halves of a letter string are integrated into an abstract representation of letter order. This representation is based on ordered pairs of two letters (bigrams); such a representation is created for input occurring at any location in the visual field. Various studies have shown hemisphere-specific effects in lexical access by using unilateral presentation of stimuli. While the hemisphere-independent means of lexical access in the SERIOL model (via bigrams) may seem inconsistent with these findings, we propose that such effects arise from the hemisphere-specific transformations necessary to create the bigram representation. We provide a theoretical account of the finding that high N (lexical neighborhood size) evokes facilitation in the RH, but not the LH (Lavidor & Ellis, 2002a, 2002b); an experiment discussed elsewhere (Whitney & Lavidor, 2003) has verified key predictions of this account. We also discuss the differing effects of word length across visual fields.