The left anterior negativity (LAN) is an ERP component that has been often associated with morphosyntactic processing, but recent reports have questioned whether the LAN effect, in fact, exists. The present project examined whether the LAN effect, observed in the grand average response to local agreement violations, is the result of the overlap between two different ERP effects (N400, P600) at the level of subjects (n=80), items (n=120), or trials (n=6160). By-subject, by-item, and by-trial analyses of the ERP effect between 300 and 500 ms showed a LAN for 55% of the participants, 46% of the items, and 49% of the trials. Many examples of the biphasic LAN-P600 response were observed. Mixed-linear models showed that the LAN effect size was not reduced after accounting for subject variability. The present results suggest that there are cases where the grand average LAN effect represents the brain responses of individual participants, items, and trials.

Words and morphemes are understood very quickly, but there are few techniques available to study the brain's response to them at the time-scale at which they occur. The left anterior negativity (LAN) has been reported as the primary ERP signature of morphosyntactic processing, but recent reports have questioned whether the LAN effect, in fact, exists, suggesting that it might result from component overlap during ERP averaging. Given that the LAN is relevant in sentence comprehension models, and that averaging procedure is widely used in ERP analysis, it becomes important to model the variability of this ERP effect. The present project examined whether the LAN effect, observed in the grand average response to local agreement violations in Spanish, is the result of the overlap between two different ERP effects (N400 and P600) at the level of subjects (n=80), items (n=120), or trials (n=6160).By-subject, by-item, and by-trial analyses of the gender violation effect between 300 ms and 500 ms showed a clear left-anterior negativity for 55% of the participants, 46% of the items, and 49% of the trials. Further analyses showed many examples of the biphasic LAN-P600 response. Mixed-linear models showed that the LAN effect size was not reduced after accounting for subject variability. The present results suggest that there are cases where the grand average LAN effect represents the brain responses of individual participants, items, and trials.

Bilinguals’ need to suppress the activation of their other language while speaking has been proposed to result in enhanced cognitive control abilities outside of language. Several studies therefore suggest shared cognitive control processes across linguistic and non-linguistic tasks. Here we investigate this potential overlap using scalp electroencephalographic recordings and the Laplacian transformation, providing an estimation of the current source density and allowing to separate EEG components in space. Fourteen Spanish-English bilinguals performed a pictureword matching task contrasting incongruent trials using cross-linguistic false cognates (e.g., a picture- foot, overlaid with distractor text: English word- PIE, i.e. the false cognate for the Spanish “pie” meaning “foot”) with congruent trials (matching English picture names and words, i.e., picture-foot, overlaid text: English word FOOT), and an unrelated control condition. In addition, participants performed an arrow-version of the Eriksen flanker task. Worse behavioral performance was observed in incongruent compared to congruent trials in both tasks. In the non-linguistic task, we replicated the previously observed congruency effect on a medialfrontal ERP peaking around 50 ms before EMG onset. A similar ERP was present in the linguistic task, was sensitive to congruency, and peaked earlier, around 150ms before EMG onset. In addition, another component was found in the linguistic task at a left lateralized anterior frontal site peaking around 200 ms before EMG onset, but was absent in the non-linguistic task. Our results suggest a partial overlap between linguistic and non-linguistic cognitive control processes and that linguistic conflict resolution may engage additional left anterior frontal control processes.