Is comprehension necessary for error detection? A conflict-based account of monitoring in speech production

Although speech is error-prone, verbal communication is successful because speakers can detect (and correct) their errors. The standard theory of speech-error detection, the perceptual-loop account, posits that the comprehension system monitors production output for errors. Such a comprehension-based monitor, however, cannot explain the double dissociation between comprehension and error-detection ability observed in the aphasic patients. We propose a new theory of speech-error detection which is, instead, based on the production process itself. The theory borrows from studies of forced-choiceresponse tasks the notion that error detection is accomplished by monitoring response conflict via a frontal brain structure, such as the anterior cingulate cortex. We implement this idea in the two-step model of word production, and test the model-derived predictions on a sample of aphasic patients. Our results show a strong correlation between patients??? error detection ability and the model???s characterization of their production skills, and no significant correlation between error detection and comprehension measures, thus supporting a production-based monitor, generally, and the implemented conflict-based monitor in particular. The successful application of the conflict-based theory to error detection in linguistic, as well as non-linguistic domains points to a domain-general monitoring system