What masked priming effects with abbreviations can tell us about abstract letter identities

Models of visual word recognition share the assumption that lexical access is based on abstract letter identities. The present study re-examined the assumption that this is because information about the visual form of the letter is lost early in the course of activating the abstract letter identities. The main support for this assumption has come from the case-independent masked priming effects. Experiment 1 used common English words presented in lowercase as targets in lexical decision, and replicated the oft-reported case-independent identity priming effect (e.g., edge-edge = EDGE-edge). In contrast, Experiment 2 using abbreviations (e.g., DNA, CIA) produced a robust case-dependent identity priming effect (e.g., DNA-DNA < dna-DNA). Experiment 3 used the same abbreviation stimuli as primes in a semantic priming lexical decision experiment. Here the prime case effect was absent, but so was the semantic priming effect (e.g., dna-GENETICS = DNA-GENETICS = LSD-GENETICS). The results question the view that information about the visual form of the letter is lost early. We offer an alternative perspective that the abstract nature of priming for common words stems from how these words are represented in the reader's lexicon. The implication of these findings for letter and word recognition is discussed. (197 words).