N400 (neuroscience) - Theories of The N400

Theories of The N400

There is still much debate as to exactly what kind of neural and comprehension processes the N400 indexes. Some researchers believe that the underlying processes reflected in the N400 occur after a stimulus has been recognized. For example, Brown and Hagoort (1993) believe that the N400 occurs late in the processing stream, and reflects the integration of a word's meaning into the preceding context (see Kutas & Federmeier, in press, for a discussion). However, this account cannot explain why items that themselves have no meaning (e.g. pseudowords) also elicit the N400. Other researchers believe that the N400 occurs much earlier, before words are recognized, and represents orthographic or phonological analysis.

More recent accounts posit that the N400 represents a broader range of processes indexing access to semantic memory. According to this account, it represents the binding of information obtained from stimulus input with representations from short- and long-term memory (such as recent context, and accessing a word's meaning in long term memory) that work together to create meaning from the information available in the current context (Federmeier & Laszlo, 2009; see Kutas & Federmeier, in press). As research in the field of electrophysiology continues to progress, these theories will likely be refined to include a complete account of just what the N400 represents.