Definition:
The P600 is an event-related potential (ERP) component — a positive-going electrical brain response peaking at approximately 600 milliseconds after stimulus onset — associated with the detection and reanalysis of syntactic violations, morphosyntactic anomalies, and the revision of initial sentence structure interpretations during language comprehension. Discovered by Lee Osterhout and Phillip Holcomb in 1992, the P600 is the counterpart to the N400 in the standard ERP framework for language: the N400 indexes semantic processing difficulty, while the P600 indexes syntactic processing difficulty and reanalysis. Together, they have been central tools for probing the neural architecture of language processing.
Basic Properties
| Property | Value |
|---|---|
| Polarity | Positive |
| Peak latency | ~500–900ms after stimulus onset |
| Scalp distribution | Bilateral parietal (sometimes frontal at earlier latencies) |
| Sensitive to | Syntactic violations, morphosyntactic agreement errors, garden-path reanalysis |
What Elicits the P600
| Stimulus type | P600 effect |
|---|---|
| Syntactic violations (“The cat chased by the dog” — ungrammatical passive) | Large P600 |
| Morphosyntactic agreement violations (“The key to the cabinets are rusty”) | P600 |
| Garden-path sentences (requiring reanalysis of initial parse) | P600 (reflects reanalysis effort) |
| Phrase structure violations | P600 (often with early LAN component) |
N400 vs. P600 Dissociation
The N400–P600 dissociation is used to probe semantic vs. syntactic processing:
- Semantic anomalies → primarily N400
- Syntactic anomalies → primarily P600 (sometimes preceded by LAN)
- Semantic-syntactic interaction violations → can elicit both or complex patterns
This dissociation has been used to argue for separate processing streams for syntax and semantics, though the complete functional independence of the two systems is debated.
P600 and Morphosyntax
A particularly well-studied application is subject-verb agreement: violations like “The key to the cabinets are rusty” (attraction errors) reliably elicit P600, allowing researchers to study the online processing of number agreement in both L1 and L2.
P600 in SLA
The P600 has been central to debates about native-like attainment in L2 syntax:
- Late L2 learners often show attenuated or absent P600 for morphosyntactic violations compared to native speakers
- Some advanced L2 learners show qualitatively native-like P600 patterns, suggesting syntactic automatization is achievable but late and effortful
- The pattern of “native-like N400 but non-native-like P600” (semantic more automatic than syntax) has been reported across multiple studies of adult L2 learners
History
Lee Osterhout and Phillip Holcomb (1992) first reported the P600 in response to syntactically anomalous phrases. Angela Friederici’s work throughout the 1990s–2000s extended the P600 framework to phrase structure violations and morphosyntax, and developed the model of the temporal sequence of ERP components during syntactic processing (ELAN → LAN → P600). The P600 has been one of the most used tools in examining syntactic processing and SLA.
Common Misconceptions
- “The P600 always reflects syntax specifically.” The P600 is sensitive to syntactic processing demands, but can also be elicited by semantic-syntactic interaction effects and even by non-linguistic incongruence in some paradigms — its functional interpretation is debated.
- “No P600 in L2 means no syntactic knowledge.” Absence or attenuation of the P600 in L2 learners may reflect processing automaticity differences rather than knowledge differences — learners may have explicit syntactic knowledge without automatic, ERP-detectable syntactic processing.
Criticisms
The interpretation of the P600 as “syntactic” while the N400 is “semantic” has been challenged by studies showing P600 effects in contexts where semantic interpretation rather than syntactic repair drives the processing. Some researchers argue for a unified account where late positive components reflect general difficulty of integration or repair regardless of the linguistic level involved.
Social Media Sentiment
The P600 is discussed primarily in academic communities. In science communication, ERP language research (including the P600) occasionally appears in popularized discussions of how the brain processes grammar in real time — a topic that connects linguistics, neuroscience, and questions about what it means to “know” a language.
Last updated: 2025-07
Practical Application
P600 research supports the importance of extensive grammatical practice in SLA: for syntactic automatization to develop (towards native-like P600 patterns), learners need extensive processing experience with the target grammar — not just explicit instruction. Communicative practice, extensive reading, and listening all provide the input processing needed for syntactic automatization.
Related Terms
See Also
Research
Osterhout, L., & Holcomb, P. J. (1992). Event-related brain potentials elicited by syntactic anomaly. Journal of Memory and Language, 31(6), 785–806.
The paper discovering the P600 as a response to syntactic violations, establishing it alongside the N400 as one of the two fundamental ERP components in language processing research.
Friederici, A. D. (2002). Towards a neural basis for auditory sentence processing. Trends in Cognitive Sciences, 6(2), 78–84.
A key review proposing the temporal sequence model of syntactic ERP processing (ELAN → LAN → P600) and linking these components to discrete stages in syntactic analysis — foundational for the neurobiology of syntax.
Osterhout, L., McLaughlin, J., Kim, A., Greenwald, R., & Inoue, K. (2004). Sentences in the brain: Event-related potentials as real-time reflections of sentence comprehension and language learning. In M. Carreiras & C. Clifton (Eds.), The On-line Study of Sentence Comprehension (pp. 181–204). Psychology Press.
An overview of ERP evidence for sentence comprehension processes and language learning, directly addressing the relationship between P600/N400 patterns and second language acquisition — essential context for SLA applications.