The early left anterior negativity (commonly referred to as ELAN) is an event-related potential in electroencephalography (EEG), or component of brain activity that occurs in response to a certain kind of stimulus.
[4] The ELAN is not elicited by sentences with other kinds of grammatical errors, such as subject-verb disagreement (*"he go to the store" rather than "he goes to the store")[9] or grammatically dispreferred and "awkward" sentences (such as "the doctor charged the patient was lying" rather than "the doctor charged that the patient was lying");[10] it only appears when it is impossible to build local phrase structure.
It appears rapidly, peaking between 100 and 300 milliseconds after the onset of the grammatically incorrect stimulus[3] (other reports have placed its time course, or latency, between 100 and 200ms,[11] "under 200ms",[1] "around 125 ms",[8] or "about 160ms"[12]).
[15][16][17] This model predicts that if the initial building of local phrase structure fails (as in the above examples *Max's of proof and *your write) then semantic processing (the brain's interpretation of the meaning of the sentence) does not go forward.
[18] This has been tested by taking advantage of two brain responses: the ELAN, which reflects the phrase-structure-building, and the N400, which reflects semantic processing; the model predicts that sentences eliciting an ELAN (a violation of local phrase structure) will not elicit an N400, since the building of phrase structure is a prerequisite for semantic processing.