Tracking the time course of letter visual-similarity effects during word recognition: A masked priming ERP investigation.

Visual similarity effects during the early stages of word processing have been consistently found for letter-like digits and symbols. However, despite its relevance for models of word recognition, evidence for letter visual-similarity effects is scarce and restricted to behavioral experiments. In two masked priming experiments, we measured event-related potential (ERP) responses to words preceded by an identical (dentist-DENTIST), a visually similar (dentjst-DENTIST), or a visually dissimilar prime (dentgst-DENTIST) to track the time course of the effects of letter visual-similarity during word processing. In the 230- to 350-ms time window, the ERPs in the visual dissimilar condition showed larger negative-going amplitudes than in the visual similar condition, which in turn behaved like the identity condition. In a later time window (400-500 ms), the visually similar condition elicited larger negative-going amplitudes than the identity condition. This pattern of findings can be accommodated within those models of word recognition that assume uncertainty concerning letter identities early in word processing that is resolved over time.