Background: Many pairs of words in Spanish, in particular many verbal forms, differ only in the syllable stressed, such as aNImo (I encourage) and aniMÓ (he encouraged). Consequently, word stress may acquire a lexical contrastive value that has been confirmed by Dupoux, Pallier, Sebastian, and Mehler (1997) for Spanish speakers though not for French speakers in auditory perception.
Method: This study contrasts the priming effect produced by pairs of written words that differ only in their stress pattern with the priming effect in repetition priming, stress only priming (with no orthographic relation), and morphological priming, in visual word recognition.
Results: The results, using short and masked prime presentation, showed facilitation for different stress (orthographically identical) pairs (rasGÓ/RASgo) compared to totally unrelated pairs (rasGÓ/RASgo) but no facilitation compared to orthographically unrelated (but stress related) pairs (PERsa/RASgo). However, identity pairs (RASgo-RASgo) produced facilitation compared to both orthographically unrelated conditions. At long SOA, orthographically related (stress unrelated) pairs produced significant facilitation, as occurred with morphologically related pairs (RASga/RASgo), on the orthographically unrelated words (PERsa/RASgo).
Conclusion: These results confirm the early and prelexical importance of word stress for lexical selection in Spanish, as is the case with orthographic and phonological features.