Error Monitoring in Speech Production: A Computational Test of the Perceptual Loop Theory

A theory of speech monitoring, proposed by Levelt (1983), assumes that the qual-ity of one’s speech is checked by the speech comprehension system. This system inspects one’s own overt speech but would also inspect an inner speech plan (‘‘the inner loop’’). We have elaborated and tested this theory by way of formalizing it as a computational model. This model includes a new proposal concerning the tim-ing relation between planning the interruption and the repair: the proposal that these two processes are performed in parallel. We attempted to simulate empirical data about the distribution of error-to-cutoff and cutoff-to-repair intervals and the effect of speech rate on these intervals (these intervals are shorter with faster speech). The main questions were (1) Is an inner monitor that utilizes the speech perception system fast enough to simulate the timing data? (2) Can the model account for the effects of speech rate on these intervals? We conclude that including an inner loop through the speech comprehension system generates predictions that fit the empirical data. The effects of speed can be accounted for, given our proposal about the time course of planning interruption and repair. A novel prediction is that the error-to-cutoff interval decreases with increasing position in the phrase. ª 2001 Academic Press Key Words: monitoring; perceptual loop theory; main interruption rule. Speakers continuously inspect the well-formedness of their own speech. Consider the events that often follow a speech error: Speech is interrupted and a new attempt is made at producing the erroneous word or phrase. This new attempt is called a ‘‘repair’ ’ (Levelt, 1983). The process of inspecting one’s own speech and taking appropriate action when errors are made is referred to as speech monitoring. Speech can be monitored for errors that stem from miscomputations at each linguistic level: for the appropriateness The research reported in this paper was funded by a grant from the Dutch Society fo