The distinctive role of vowel harmony in visual word recognition: The case of Turkish.

Vowel harmony is a phenomenon in which the vowels in a word share some features (e.g., frontness vs. backness). It occurs in several families of languages (e.g., Turkic and Finno-Ugric languages) and serves as an effective segmenting cue in continuous speech and when reading compound words. The present study examined whether vowel harmony also plays a role in visual word recognition. We chose Turkish, a language with four front and four back vowels in which approximately 75% of words are harmonious. If vowel harmony contributes to the formation of coherent phonological codes during lexical access, harmonious words will reach a stable orthographic-phonological state more rapidly than disharmonious words. To test this hypothesis, in Experiment 1, we selected two types of monomorphemic Turkish words: harmonious (containing only front vowels or back vowels) and disharmonious (containing front and back vowels)-a parallel manipulation was applied to the pseudowords. Results showed faster lexical decisions for harmonious than disharmonious words, whereas vowel harmony did not affect pseudowords. In Experiment 2, where all words were harmonious, we found a small but reliable advantage for disharmonious over harmonious pseudowords. These findings suggest that vowel harmony helps the formation of stable phonological codes in Turkish words, but it does not play a key role in pseudoword rejection.