Poster B35, Tuesday, August 20, 2019, 3:15 – 5:00 pm, Restaurant Hall
Dividing Attention During Language Comprehension Affects ERP Components of Contextual Integration and Revision
Ryan Hubbard1, Kara Federmeier1;1University of Illinois, Urbana-Champaign
Prior behavioral and electrophysiological work has demonstrated that when individuals process language input, such as reading a sentence, they can use the contextual information provided by the sentence to facilitate processing of upcoming information, likely through predictive processing. For instance, electrophysiological research has shown that the N400 of the ERP is reduced for expected words in strongly constraining sentences compared to weakly constraining sentences, while unexpected words in either context produced large N400s (Federmeier et al., 2007); additionally, disconfirmed predictions elicit a later frontal positivity which likely reflects revision of the previously built contextual representation in order to integrate the unexpected but plausible information. However, these anticipatory comprehension mechanisms may not always be engaged; for instance, when presentation rate is speeded (Wlotko & Federmeier, 2015), the typically observed ERP responses suggestive of prediction are diminished. These results suggest that these anticipatory mechanisms are flexibly engaged and require top-down allocation of resources, and thus may rely on attentional processes. Here, we tested this hypothesis with a divided attention language comprehension paradigm. We first developed a novel dot tracking task that allowed participants to focus their eyes centrally in order to still read words, but required constant attention in order to track moving dots. In a separate group of 8 participants, we verified the attentional demands of the task in a dual-task oddball paradigm designed to elicit P300 ERP responses (Isreal et al., 1980). The dot tracking task reliably reduced P300 amplitude and increased oddball reaction times. We then tested a new group of participants in an experiment in which they first read strongly or weakly constraining sentences with expected or unexpected endings (Federmeier et al., 2007), and then read a new set of sentences while continuously tracking dot movements. Accuracy for comprehension questions on the sentences was reduced in the dual-task condition compared to the standard reading condition. Additionally, a frontal positivity for prediction violations was observed during standard reading, but was abolished when attention was divided. Finally, divided attention also affected contextual integration, as indexed in the P2 / N400 time window. Namely, the difference in ERP amplitude between expected and unexpected endings in strong constraint sentences was larger in standard reading than when attention was divided, and this difference was due to amplitude differences of expected endings. These results demonstrate that multiple aspects of language comprehension utilize attentional resources, and when attention is divided, comprehension may be negatively impacted and contextual revision may be completely disengaged. These results also potentially give insight into what mechanisms are affected in populations with language comprehension difficulties, such as older adults (Wlotko, Lee, & Federmeier, 2010); namely, deficits in attentional processing may lead to deficits in language processing.
Themes: Meaning: Combinatorial Semantics, Meaning: Lexical Semantics
Method: Electrophysiology (MEG/EEG/ECOG)