Co-occurrence restrictions on identical consonants in the Hebrew lexicon: Are they due to similarity?

It is well known that Semitic languages restrict the co-occurrence of identical and homorganic consonants in the root. The IDENTITY HYPOTHESIS attributes this pattern to distinct constraints on identical and nonidentical homorganic consonants (e.g. McCarthy 1986, 1994). Conversely, the SIMILARITY HYPOTHESIS captures these restrictions in terms of a single monotonic ban on perceived similarity (Pierrehumbert 1993; Frisch, Broe & Pierrehumbert 1997). We compare these accounts by examining the acceptability of roots with identical and homorganic consonants at their end. If well-formedness is an inverse, monotonic function of similarity, then roots with identical (fully similar) consonants should be less acceptable than roots with homorganic (partially similar) consonants. Contrary to this prediction, Hebrew speakers prefer root final identity to homorganicity. Our results suggest that speakers encode long-distance identity among root radicals in a manner that is distinct from feature similarity.