Using the readiness potential of button-press and verbal response within spoken language processing.

BACKGROUND

Even though research in turn-taking in spoken dialogues is now abundant, a typical EEG-signature associated with the anticipation of turn-ends has not yet been identified until now.

NEW METHOD

The purpose of this study was to examine if readiness potentials (RP) can be used to study the anticipation of turn-ends by using it in a motoric finger movement and articulatory movement task. The goal was to determine the preconscious onset of turn-end anticipation in early, preconscious turn-end anticipation processes by the simultaneous registration of EEG measures (RP) and behavioural measures (anticipation timing accuracy, ATA). For our behavioural measures, we used both button-press and verbal response ("yes"). In the experiment, 30 subjects were asked to listen to auditorily presented utterances and press a button or utter a brief verbal response when they expected the end of the turn. During the task, a 32-channel-EEG signal was recorded.

RESULTS

The results showed that the RPs during verbal- and button-press-responses developed similarly and had an almost identical time course: the RP signals started to develop 1170 vs. 1190 ms before the behavioural responses.

COMPARISON WITH EXISTING METHODS

Until now, turn-end anticipation is usually studied using behavioural methods, for instance by measuring the anticipation timing accuracy, which is a measurement that reflects conscious behavioural processes and is insensitive to preconscious anticipation processes.

CONCLUSION

The similar time course of the recorded RP signals for both verbal- and button-press responses provide evidence for the validity of using RPs as an online marker for response preparation in turn-taking and spoken dialogue research.