Perceptual magnet and phoneme boundary effects in speech perception: Do they arise from a common mechanism?

The question of whether sensitivity peaks at vowel boundaries (i.e., phonem e boundary effects) and sensitivity minima near excellent category exemplar s (i.e., perceptual magnet effects) stem from the same stage of perceptual processing was examined in two experiments. In Experiment 1, participants g ave phoneme identification and goodness ratings for 13 synthesized English /i/ and /e/ vowels. In Experiment 2, participants discriminated pairs of th ese vowels. Either the listeners discriminated the entire range of stimuli within each block of trials, or the range within each block was restricted to a single stimulus pair. In addition, listeners discriminated either one- step or two-step intervals along the stimulus series. The results demonstra ted that sensitivity peaks at vowel boundaries were more influenced by stim ulus range than were perceptual magnet effects; peaks in sensitivity near t he /i/-/e/ boundary were reduced with restricted stimulus ranges and one-st ep intervals, but minima in discrimination near the best exemplars of /i/ w ere present in all conditions.