Shared or separated representations for letters with diacritics?

Understanding the front end of visual word recognition requires us to identify the processes by which letters are identified. Since most of the work on letter recognition has been conducted in English, letter perception modeling has been limited to the 26 letters of the Latin alphabet. However, many writing systems include letters with diacritic marks. In the present study, we examined whether diacritic letters are a mere variant of their base letter, and thus share the same abstract representation, or whether they function as separate elements from any other letters, and thus have separate representations. In Experiments 1A and 1B, participants performed an alphabetical decision task combined with masked priming. Target letters were preceded by the same letter (e.g., a-A), by a diacritic letter (e.g., â-A), or by an unrelated letter (e.g., z-A). The results showed that the primes sharing nominal identity (e.g., a) facilitated target processing as compared to unrelated primes (e.g., z), but that primes that included a diacritic mark (e.g., â) did not, with reaction times being similar to those in the unrelated priming condition. In Experiment 2 we replicated these results in a lexical decision task. Overall, this demonstrates that as long as diacritics are used in scripts to distinguish between lexical entries, the diacritic letters are not mere variants of their base letters but constitute unitary elements of the script in their own right, with diacritics contributing to the overall visual shape of a letter.