Harry Potter and the Chamber of What?: the impact of what individuals know on word processing during reading

ABSTRACT

During reading, effects of contextual support indexed by N400 – a brain potential sensitive to semantic activation/retrieval – amplitude are presumably mediated by comprehenders’ world knowledge. Moreover, variability in knowledge may influence the contents, timing, and mechanisms of what is brought to mind during real-time sentence processing. Since it is infeasible to assess the entirety of each individual’s knowledge, we investigated a limited domain – the narrative world of Harry Potter (HP). We recorded event-related brain potentials while participants read sentences ending in words more/less contextually supported. For sentences about HP, but not about general topics, contextual N400 effects were graded according to individual participants’ HP knowledge. Our results not only confirm that context affects semantic processing by ∼250 ms or earlier, on average, but empirically demonstrate what has until now been assumed – that N400 context effects are a function of each individual’s knowledge, which here is highly correlated with their reading experience.

KEYWORDS:

• N400
• individual differences
• knowledge
• sentence processing
• event-related brain potentials

Acknowledgements

We thank Katherine DeLong, Tom Urbach, Jeffrey Elman, Seana Coulson, Victor Ferreira, and Zhuowen Tu for feedback on this work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 For N400 context effects, we followed up on interactions with electrode in a distribution analysis containing a subset of 16 electrodes (following the procedure in Federmeier & Kutas, 1999) which supported this interpretation. For both sentences types, N400 context effects were centro-posterior; for control, but not HP, sentences, the N400 context effect was somewhat right lateralised.

2 For post-N400 context effects, we followed up on interactions with electrode in a distribution analyses containing a subset of 16 electrodes (as for our N400 context effects). These analyses confirmed that for control sentences, N400 context effects were left/frontal, while no context effects were present on the late positivity for HP sentences.

Additional information

Funding

This research was supported by Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) [grant number RO1HD022614] to MK and Frontiers of Innovation in Science Program grant to MT.