Early left anterior negativity

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. It is characterized by a negative-going wave that peaks around 200 milliseconds or less after the onset of a stimulus, and most often occurs in response to linguistic stimuli that violate word-category or phrase structure rules (as in *the in room instead of in the room). As such, it is frequently a topic of study in neurolinguistics experiments, specifically in areas such as sentence processing. While it is frequently used in language research, there is no evidence yet that it is necessarily a language-specific phenomenon. More recent work has criticized the design of many of the foundational studies that characterized the ELAN, such that apparent ELAN effects might be the result of spillover from words prior to the onset of the critical word. This raises important questions about whether the ELAN is a true ERP component or an artifact of certain experimental designs. The ELAN was first reported by Angela D. Friederici as a response to German sentences with phrase structure violations, such as *the pizza was in the eaten (as opposed to the pizza was eaten); it can be elicited by English phrase structure violations such as *Max's of proof (as opposed to Max's proof) or your write (as opposed to you write). 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") 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"); 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 (other reports have placed its time course, or latency, between 100 and 200ms, "under 200ms", "around 125 ms", or "about 160ms").