Kolk & Postma [2] proposed, following Dell & O'Seaghdha [1], that when a speaker chooses a word, phonologically-related words as well as the intended word are activated. Initially, the activations of all these words are similar, though eventually the intended word reaches a higher asymptotic value when activation is complete [1]. According to Kolk & Postma [2], if a response is made in the phase where activation is building up (rather than at full activation), there is a higher chance of the competing, rather than the intended, word being selected (i.e. an error). They propose that a speaker detects such errors when they are produced overtly using the perceptual system, and a monitor in the linguistic system responds by interrupting and initiating the correction [2].
Word repetition and hesitation (not errors in themselves) have been regarded as signifying underlying errors that are detected and interrupted before speech is output in a similar way to overt errors. An assumption in [2] is that activation for a word stops (or, if it continues, is ignored) immediately a candidate word is selected. The brain processes responsible for speech production have massive parallel capacity. Consequently, activation for all the candidates for a word slot could continue beyond the point where a word is selected in cases where a word is responded to prematurely. when the selected word reaches asymptote, the relative activations of this and the other candidate words indicate when an error has occurred (when the selected word has a lower activation than one of the competing words), and what correction is appropriate (the word with the highest activation). This provides the basis for error detection and correction without the need for a perceptual monitor. Continuing the buildup of activation after a word has been selected, implies that activation of nearby words in its phrase overlaps. It is shown, with some realistic assumptions about how activation builds up and decays across different words in a phrase, that this model predicts word repetition and hesitation and also part-word disfluencies (a characteristic of stuttering), again without the need for a perceptual monitor.
s Dell, G. S. / O'Seaghdha (1991): "Mediated and convergent lexical priming in language production: a comment to Levelt et al.", Psychol. Review 98, 604-614. Kolk; H. H. J. A. / Postma (1997): "Stuttering as a covert-repair phenomenon," in R. F. Curlee and H. Siegel (eds.), Nature and treatment of stuttering: new directions (Allyn & Bacon, Boston, MA, USA), 182-203.