Contextual similarity between targets and competitors, whether semantic or phonological, often leads to behavioral interference in language production. It has been assumed that resolving such interference relies on control processes similar to those involved in tasks such as Stroop. This article tests this assumption by comparing the electrophysiological signatures of interference resulting from a contextual similarity versus a Stroop-like manipulation. In blocks containing two items, participants repeatedly named pictures that were semantically related, phonologically related, or unrelated (contextual similarity manipulation). In straight blocks, the pictures were named by their canonical names. In reverse blocks, participants had to reverse the names (Stroop-like manipulation). Both manipulations led to behavioral interference, but with different electrophysiological profiles. Whole-scalp stimulus-locked and response-locked analyses of semantic and phonological similarity pointed to a system with global modularity with some degree of cascading and interactivity, whereas the effect of phase reversal was sustained and of the opposite polarity. More strikingly, a representational similarity analysis showed a biphasic pattern for Stroop-like reversal, with earlier higher similarity scores for the reverse phase flipping into lower scores ~500 msec poststimulus onset. In contrast, contextual similarity induced higher similarity scores up to articulation. Finally, response-locked mediofrontal components indexing performance monitoring differed between manipulations. Correct response negativity's amplitude was lower in the phonological blocks, whereas a pre-correct response negativity component had higher amplitude in reverse versus straight blocks. These results argue against the involvement of Stroop-like control mechanisms in resolving interference from contextual similarity in language production.

New theories of monitoring in language production, regardless of their mechanistic differences, all posit monitoring mechanisms that share general computational principles with action monitoring. This perspective, if accurate, would predict that many electrophysiological signatures of performance monitoring should be recoverable from language production tasks. In this study, we examined both error-related and feedback-related EEG indices of performance monitoring in the context of a typing-to-dictation task. To disentangle the contribution of the external from internal monitoring processes, we created a condition where participants immediately saw the word they typed (the immediate-feedback condition) versus one in which displaying the word was delayed until the end of the trial (the delayed-feedback condition). The removal of immediate visual feedback prompted a stronger reliance on internal monitoring processes, which resulted in lower correction rates and a clear error-related negativity. Compatible with domain-general monitoring views, an error positivity was only recovered under conditions where errors were detected or had a high likelihood of being detected. Examination of the feedback-related indices (feedback-related negativity and frontocentral positivity) revealed a two-stage process of integration of internal and external information. The recovery of a full range of well-established EEG indices of action monitoring in a language production task strongly endorses domain-general views of monitoring. Such indices, in turn, are helpful in understanding how information from different monitoring channels are combined.

Response selection is often studied by examining single responses, although most actions are performed within an overarching sequence. Understanding processes that order and execute items in a sequence is thus essential to give a complete picture of response selection. In this study, we investigate response selection by comparing single responses and response sequences as well as unimanual and bimanual sequences. We recorded EEG while participants were typing one- or two-keystroke sequences. Irrespective of stimulus modality (visual or auditory), response-locked analysis revealed distinct contralateral and ipsilateral components previously associated with activation and inhibition of alternative responses. Unimanual sequences exhibited a similar activation/inhibition pattern as single responses, but with the activation component of the pattern expressed more strongly, reflecting the fact that the hand will be used for two strokes. In contrast, bimanual sequences were associated with successive activation of each of the corresponding motor cortices controlling each keystroke and no traceable inhibitory component. In short, the activation component of the two-keystroke sequence EEG pattern can be understood from the addition of activation components of single-stroke sequences; the inhibition of the hand not being used is only evidenced when that hand is not planned for the next stroke.