Does discourse congruence influence spoken language comprehension before lexical association? Evidence from event-related potentials

Abstract

The goal of this study was to examine how lexical association and discourse congruence affect the time course of processing incoming words in spoken discourse. In an event-related potential (ERP) norming study, we presented prime-target pairs in the absence of a sentence context to obtain a baseline measure of lexical priming. We observed a typical N400 effect when participants heard critical associated and unassociated target words in word pairs. In a subsequent experiment, we presented the same word pairs in spoken discourse contexts. Target words were always consistent with the local sentence context, but were congruent or not with the global discourse (e.g., “Luckily Ben had picked up some salt and pepper/basil,” preceded by a context in which Ben was preparing marinara sauce (congruent) or dealing with an icy walkway (incongruent). Event-related potential effects of global discourse congruence preceded those of local lexical association, suggesting an early influence of the global discourse representation on lexical processing, even in locally congruent contexts. Furthermore, effects of lexical association occurred earlier in the congruent than incongruent condition. These results differ from those that have been obtained in studies of reading, suggesting that the effects may be unique to spoken word recognition.

Keywords:

• Discourse congruence
• Lexical association
• Connected speech
• N400

Acknowledgements

This work was funded by grants R01 MH066271-01A1, R24 MH081807 and R01HD060440-06A2.

Notes

¹In order to address whether differences in cloze probability among conditions could have contributed to the pattern of results reported in the current manuscript, we conducted additional analyses using only a subset of experimental stimuli (37 out of 72) from the congruent associated condition that matched the average cloze probability of the other conditions. The results of this analysis were consistent with those described below, showing that the current results cannot be attributed to differences in cloze probability across conditions.

²The duration of this pause was set to one second in order to match the average of the naturally produced pauses between sentences one and two.

³As pointed out by one of the reviewers, there were several methodological differences between the current experiment and the studies in which such P600 effects have been found. In contrast to Kuperberg et al., (2003), the current experiment used stories presented in the auditory modality as opposed to the visual modality; true/false comprehension questions as opposed to metalinguistic judgments; and critical words that were in sentence final positions as opposed to middle sentence positions. We suggest that these three methodological differences do not drive the absence of a P600 effect in our study, since reliable P600 effects were recently reported on words in the middle of a sentence akin to those found in Kuperberg et al., (2003) using the auditory modality and true/false comprehension questions (Nakano, Saron, & Swaab, 2010). Instead , as argued above, we suggest that a P600 is not elicited when the conflict arises between local semantic associations and the constructed discourse representation.