In the present study we investigated event-related brain potentials (ERPs) related to verbal slips. Tongue twisters where used to reliably induce speech errors.
Two German tongue-twisters and four matched control sentences where first presented in a “karaoke” fashioned display to the subjects, indicating a certain segmentation and pace for the repetitions to follow. While overtly repeating a given sentence, subjects had to fixate a cross on the center of the screen. Subjects where previously trained to time their repetition segment-by-segment to a train of click-tones, also given with the initial display of each sentence. The pace was identical for all sentences and their segments.
ERPs where calculated time locked to click-tones associated with verbal slips and correct vocalisations in tongue-twisters as well as correct vocalisations in control sentences. Average waveforms for error trials where more negative going, than for correct trials.
Results are discussed in relation to the possible neural generators underlying this error negativity as well as in relation to the competing plans hypothesis.