Interference between phonemes during phoneme monitoring: evidence for an interactive activation model of speech perception.

We explore the recent finding (Newman & Dell, 1978) that the time needed to detect a target phoneme in a phoneme monitoring task is increased when the preceding word contains a phoneme similar to the target. Normal adult native speakers of English monitored auditorily presented sentences and responded as quickly as possible whenever they detected a specified phoneme. We found that preceding word-initial phonemes, despite being processed more quickly, increased the response latency to the following target phoneme more than did preceding word-medial phonemes. There was also an increase in response latency even when the subject could be highly certain that the similar preceding phoneme was not an instance of the target phoneme. We argue that the interference effects are due to fundamental characteristics of perceptual processing and that more time is needed to categorize the target phoneme. We present a computer simulation using an interactive activation model of speech perception to demonstrate the plausibility of our explanation.