Foreign-accented sentence comprehension is challenging for older adults: ERP evidence from semantic and grammar processing

Abstract

Research has shown that older adults have increased difficulty comprehending foreign-accented speech. As these studies have only used behavioral measures, we exploited the fine-grained temporal resolution of EEG/ERPs to examine neural signatures of foreign- and native-accented sentence comprehension in older adults. Older adults, all normal-hearing monolingual English speakers, listened to foreign Chinese-accented and native English-accented sentences while ERPs were recorded. Foreign- and native-accented sentences contained semantic or pronoun errors, or were semantically and grammatically correct. We also gathered behavioral measures of sentence comprehension, and examined how neural activity during sentence processing relates to individual differences in listeners’ attitudes towards accented speakers, linguistic and cognitive skills, and hearing acuity. Older adults showed high comprehension accuracy of both foreign-accented and native-accented sentences. In contrast, ERP data showed different neural responses to foreign- and native-accented sentences: Semantic errors elicited an N400 effect in native-accented sentences, but not in foreign-accented sentences. Grammatical errors elicited a P600, not further qualified by accent type. Hearing acuity and individual differences in language attitudes, cognitive and linguistic variables did not systematically correlate with ERP patterns. These findings suggest that older adults are ultimately engaging in foreign-accented sentence comprehension, but non-native pre-lexical speech signals do not attain activation needed for strong lexical activation during online processing, resulting in strained and more effortful higher-level processing of semantics downstream the sentence.