Martin, A. E., & Nieuwland, M. S.
(2014). Similarity-based interference during comprehension of noun phrases: evidence from ERPs. Poster presented at the 6th Annual Society for the Neurobiology of Language Conference, Amsterdam, The Netherlands.
Current accounts of sentence comprehension invoke the notion of retrieval interference as a primary determinant of difficulty during processing [1-2]. Specifically, similarity between constituents (e.g., NP feature-overlap)
has been argued to interfere when people resolve subject-verb or anaphoric dependencies [3-7]. We ask whether similarity-based interference effects arise as a function of multiple NPs in the discourse that overlap in gender and/or number. We take a novel approach by
examining interference effects at the second NP rather than downstream after “maintaining” multiple NPs [6-8], using ERPs to establish quantitative and qualitative
processing consequences. We used the empty category PRO to introduce two NPs, only the second NP could be PRO controller (e.g., “While [PRO] talking to the waitresses, the man/men/woman/women inspected the menu”). If feature overlap affects processing of the second NP, most interference should occur under gender- and number-matching NPs. Because this
interference crosses the subject-object distinction, we predicted that interference would elicit a P600 effect, the effect most reliably associated with syntactic processing
difficulties . Methods: During EEG recording, 24 participants read 160 grammatical sentences (40 per
condition) in a 2(gender: match, mismatch) x 2(number: match, mismatch) factorial design where the first clause introduced the object-NP and had PRO as subject, and
the matrix clause introduced the controller of PRO. Subject and object NPs could overlap in gender and/or number. We fully counterbalanced 160 male/female
singular/plural gender-definitional nouns as object NPs, and as critical NP always ‘woman/man/girl/boy’ (or plural form). Sentences were mixed with 156 fillers and
presented word by word (300 ms duration, 200 ms blank), followed by intermittent comprehension questions (85%
response accuracy). Results: Across all electrodes, a significant gender by number interaction was observed (500-800 ms window ; F(1,23)=6.02, p<.05), due to a
robust P600 effect of number-mismatch in the gender-match conditions (M=-1.18, F(1,23)=8.04, p=.01), that did
not occur in the gender-mismatch conditions (M=-.17, F(1,23)=.18, ns). No distributional effects were observed.
Conclusions: The P600 effect for double-match NPs suggests that interference was driven by similarity
contingent upon matching gender and number. Our results testify to the strength of gender-cues during incremental processing, consistent with memory-based
accounts of discourse comprehension [2-7]. The results suggest that when features maximally overlap, the subject NP may be momentarily considered as an anaphor for the more distinctive (i.e., first-mentioned and semantically richer) object NP. Alternatively, the P600 may reflect
increased discourse complexity stemming from similar NPs . Our results imply a central role for interference during comprehension, even of simple grammatical sentences. References:  Lewis, Vasishth, Van Dyke, 2006;  McElree, Foraker, & Dyer, 2003;  Gerrig & O’Brien, 2005;  Gordon, Hendrick, & Johnson, 2004;  McKoon & Ratcliff, 1998;  Van Dyke & McElree, 2006;
 Gordon, Hendrick, Johnson, & Lee, 2006;  Wager & Phillips, 2013;  Osterhout & Holcomb, 1992;  Kaan
& Swaab, 2003