The interrelation between stimulus range and the number of response categories in vowel categorization.

Abstract

The categorization of speech sounds is influenced by the preceding sound context. Specifically, listeners shift their boundary between two categories toward the values of the preceding sounds. Such boundary shifts are larger if listeners can respond with fewer categories than are actually present in the stimuli. This study investigates the influence of the stimulus range on boundary shifts between vowels and whether these shifts are smaller if listeners can choose from more categories than are present in the stimuli. The F1 continuum between Spanish /i/ and /e/ was presented to Peruvian listeners in three ranges. Half of the listeners responded with /i/ and /e/, the other half chose from the five Spanish vowels. Boundary shifts between /i/ and /e/ as a function of the stimulus range were observed, which were smaller when listeners could choose from five categories. In subsequent analyzes, the influence of the preceding sound context appeared smaller for listeners that could choose from five categories. Al...