Inhibition and facilitation in visual word recognition: prefrontal contribution to the orthographic neighborhood size effect.

The recognition of words is a central component of language processing. A major role for visual word recognition has been attributed to the orthographic neighbors of a word, i.e., words that are orthographically similar to a target word. It has been demonstrated that the presence of orthographic neighbors facilitates the recognition of words, but hinders the rejection of nonwords. It is therefore assumed that representations of orthographic neighbors are at least partially activated during word recognition, and that they influence word recognition depending on the specific task context. In the present study, we used fMRI to examine the neural bases of the effect of orthographic neighborhood size on speeded lexical decisions to words and nonwords. Our results demonstrate lexicality x neighborhood size interactions in mid-dorsolateral and medial prefrontal cortex, suggesting the involvement of a domain-general, extra-lexical process for orthographic neighborhood effects on word and nonword processing. This result challenges computational models that offer purely lexical accounts of the orthographic neighborhood effect and suggests an important role for executive control functions during visual word recognition.