Although more automatic aspects of language processing are relatively well-preserved with age, language processes that require more top-down resources, such as processing sentences with complex structure or selecting appropriate meanings for ambiguous words in a context, is less efficient in older adults. Previous Dutch study has shown that in younger adults, ambiguous pronouns, compared to unambiguous ones, elicited a sustained frontal negativity (Nieuwland & Van Berkum, 2006). Whether such processes are affected by healthy aging is still unknown. However, similar frontal negativity effects found in homographs were shown to be reduced in older adults (Lee & Federmeier, 2011, 2012). The current study thus aims to verify whether the frontal negativity elicited during comprehending referential ambiguity is also affected by aging.
We manipulated the referential relations between pronouns and the number of possible antecedents in the sentences such that each pronoun has either (1) two antecedents (referentially ambiguous), (2) one antecedent (referentially ambiguous), or (3) zero antecedent (referentially failure). Our results showed that, consistent with Dutch findings, relative to unambiguous pronouns, younger adult showed a sustained frontal negativity to ambiguous pronouns and a central-posterior P600 effect to referentially failing pronouns. Older adults did not show the sustained frontal negative ambiguity effect, but a trend of central-posterior negativity instead. In addition, as a group, older adults showed a smaller and delayed P600 effect to referentially failing pronouns but both N400 and P600 were found in individual data. Our present findings thus suggest that, consistent with previous homograph studies, top-down resources recruited by younger adults to resolve referential ambiguity are less available with advancing age. In addition, older adults may comprehend referential failing sentences in manners that are qualitatively different from what younger adult do.