Performance errors are associated with robust behavioural and EEG effects. However, there is a debate about the nature of the relationship between these effects and implicit vs. explicit error awareness. Our aim was to study the relationship between error related electrophysiological effects, such as spectral perturbations in fronto-medial theta band oscillations (FMT), and error awareness in typing. Typing has an advantage as an experimental paradigm in that detected errors are quickly and habitually signalled by the participant using backspace, allowing separation of detected from undetected errors without interruption in behaviour. Typing is thought to be controlled hierarchically via inner and outer loops, which rely on different sources for error detection. Touch-typist participants were asked to copy-type 100 sentences as EEG was recorded in the absence of visual feedback. Continuous EEG data were analysed using independent component analysis (ICA). Time-frequency and ERP analyses were applied to emergent independent components. The results show that single-trial FMT parameters and Error Related Negativity (ERN) amplitude predict overt, adaptive post-error actions such as error correction via backspace; and, post-error slowing after errors, reflecting implicit error awareness. In addition, we found that those uncorrected errors which were slowed down the most were also the ones associated with a high level of FMT activity. Our results as a whole show that FMT are related to neural mechanism involved in explicit awareness of errors, and input from inner loop is sufficient for error correction in typing.
Public SignificanceWe investigated the patterns of brain activity which precede errors and error-correction during skilled typing. This is interesting because it tests how theories of action and error-monitoring apply in a domain where actions are made extremely rapidly (up to ten keys per second). Electroencephalography (EEG) allows us to identify signature changes which have previously been associated with error-related processes in the brain. We showed that two of these signature patterns, the "error related negativity" (ERN) and "fronto-medial theta band oscillations" (FMT), both predict whether a typist is likely to notice and correct an error they make, as well as predicting how much typing slows down after an uncorrected error. The results support the idea -which has been contested -that the ERN reflects our explicit recognition that we have made a mistake.