The nature of phoneme representation in spoken word recognition

Four experiments used the Psychological Refractory Period logic to examine
whether integration of multiple sources of phonemic information has a decisional
locus. All experiments made use of a dual-task paradigm in which participants
made forced-choice color categorization (Task 1), and phoneme categorization
(Task 2) decisions at varying stimulus onset asynchronies. In Experiment 1, Task
2 difficulty was manipulated using words containing matching or mismatching
coarticulatory cues to the final consonant. The results showed that difficulty and
onset asynchrony combined in an underadditive way, suggesting that the
phonemic mismatch was resolved prior to a central decisional bottleneck. Similar
results were found in Experiment 2 using non-words. In Experiment 3, the
manipulation of task difficulty involved lexical status, which once again revealed
an underadditive pattern of response times. Finally, Experiment 4 compared this
pre-bottleneck variable with a decisional variable: response key bias. The latter
showed an additive pattern of responses. The experiments show that resolution of
phonemic ambiguity can take advantage of cognitive “slack” time at short
asynchronies, indicating that phonemic integration takes place at a relatively
early stage of spoken-word recognition.