The early left anterior negativity is an event-related potential in electroencephalography, 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 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.
Characteristics
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 ; it can be elicited by English phrase structure violations such as *Max's of proof or *your write. The ELAN is not elicited by sentences with other kinds of grammatical errors, such as subject-verb disagreement or grammatically dispreferred and "awkward" sentences ; 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. The speed of the ELAN may also be affected by characteristic of the violating stimuli; the ELAN appears later to visual stimuli that are fuzzy or difficult to see, and may occur earlier in morphologically complex spoken words where much information about the meaning of the word precedes the word's recognition point. Its name derives from the fact that it is picked up most robustly by EEG sensors on the left front regions of the scalp; it may sometimes, however, have a bilateral distribution. Some authors consider the ELAN to be a separate response from the left anterior negativity, while others label it as just an early version of the LAN. The ELAN has been reported in languages such as English, German, Dutch, Chinese, and Japanese. It is possible, though, that it is not a response specific to language.
Use in neurolinguistics
The ELAN response has played an important role in studies of sentence processing, particularly in the development of the so-called "serial model" or "syntax-first model" of sentence processing. According to this model, the brain's first step in processing sentences is to organize input and build local phrase structure, and it does not process semantic information or meaning until after this step has succeeded. This model predicts that if the initial building of local phrase structure fails then semantic processing does not go forward. 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 will not elicit an N400, since the building of phrase structure is a prerequisite for semantic processing. These types of studies have had subjects read or listen to sentences that have both a syntactic and semantic violation in the same place. Some such studies have found such sentences to elicit an ELAN and no N400, thus supporting the claim of the "serial model", while others have found both an ELAN and an N400, challenging the model.
