Letter-similarity effects in braille word recognition

Letter-similarity effects are elusive with common words in lexical decision experiments: viotin and viocin (base word: violin) produce similar error rates and rejection latencies. However, they are robust for stimuli often presented with the same appearance (e.g., misspelled logotypes such as anazon [base word: amazon] produce more errors and longer latencies than atazon). Here, we examine whether letter-similarity effects occur in reading braille. The rationale is that braille is a writing system in which the sensory information is processed in qualitatively different ways than in visual reading: the form of the word's letters is highly stable due to the standardisation of braille and the sensing of characters is transient and somewhat serial. Hence, we hypothesised that the letter similarity effect would be sizable with misspelled common words in braille, unlike the visual modality. To test this hypothesis, we conducted a lexical decision experiment with blind adult braille readers. Pseudowords were created by replacing one letter of a word with a tactually similar or dissimilar letter in braille following a tactile similarity matrix (e.g., [ausor] vs [aucor]; baseword: [autor]). Bayesian linear mixed-effects models showed that the responses to tactually similar pseudowords were less accurate than to tactually dissimilar pseudowords-the response times (RTs) showed a parallel trend. This finding supports the idea that, when reading braille, the mapping of input information onto abstract letter representations is done through a noisy channel.