Is case-invariant word recognition truly abstract? Insights from the diffusion model

Skilled readers recognize words efficiently despite wide variation in their visual form (e.g., table, TABLE, table , table ). The present experiments examined how case invariance emerges in the earliest moments of word recognition using the masked priming technique to isolate early stages of processing. Specifically, we tested whether case alternation disrupts access to abstract orthographic representations or merely modulates early perceptual encoding. In two masked priming lexical decision experiments, we compared matched-case and alternating-case identity primes (e.g., TABLE–TABLE, tAbLe–TABLE) with unrelated baselines, while manipulating prime–target visual overlap (equal vs. reduced prime size). In the two experiments, we found a sizable overall masked identity priming effect that was slightly larger for matched-case identity primes than for alternating-case primes. Diffusion-model analyses showed that priming effects were expressed mainly as reductions in nondecision time ( T er parameter), indicating facilitation at early encoding stages. These results indicate that early orthographic processing is largely, but not completely, case-invariant; alternating-case primes rapidly activate abstract letter identities, while a small residual benefit remains for matched-case primes, constraining models of visual word recognition.