The impact of semantic memory organization and sentence context information on spoken language processing by younger and older adults: An ERP study

Abstract

To examine changes in semantic memory organization and use during aging, we recorded event-related potentials as younger and older adults listened to sentences ending with the expected word, an unexpected word from the same semantic category, or an unexpected word from a different category. Half of the contexts were highly constraining. In both groups, expected words elicited less negativity 300-500 ms (N400) than unexpected ones, and unexpected words elicited smaller N400s when these were categorically related. Whereas younger adults showed the greatest N400 reduction to unexpected but related words in high constraint contexts, older adults showed the opposite tendency. Thus, unlike younger adults, older adults as a group do not seem to be using context predictively. Older adults with higher verbal fluency and larger vocabularies, however, showed the younger response pattern, suggesting resource availability may offset certain age-related changes.

Multiple effects of sentential constraint on word processing

“…Although further work is needed to clearly link this electrophysiological pattern with results seen in behavioral measures, a likely hypothesis is that this effect could be related to the narrowed scope of behavioral facilitation (on lexical decision times) observed for strongly constraining sentences (Schwanenflugel and LaCount, 1988). If this response is indeed related to prediction, then it should be reduced or absent under conditions where predictive processing is less likely, as has been reported for elderly individuals (Federmeier et al, 2002) and for right-hemisphere-biased processing (Federmeier and Kutas, 1999a); we are currently examining this issue further. A similar frontal positivity (650 to 850 ms) was observed in Spanish-English bilinguals in response to low cloze probability words completing English sentence fragments and idioms (e.g., The driver of the speeding car was given a citation.…”

Foreign-accented speech modulates linguistic anticipatory processes

“…The more appropriate the word for a given context, the smaller the amplitude, replicating Federmeier et al (2002). In other words, we expect the N400 amplitudes to be smaller for Best Completions than for Related words, and smaller for Related than for Unrelated words.…”

“…Hence, going a step further on anticipation capacities during sentence comprehension, a second question of interest is whether listeners are able to pre-activate other words semantically related to the expected ones when listening to foreign-accented speech, as they do during native speech comprehension (Federmeier et al, 2002). As we mentioned above, if listeners narrow the possible lexical candidates during foreign-accented speech comprehension (Goslin et al, 2012), then we would expect that only sentences' best completions are anticipated when listening to foreign-accented speakers.…”

“…Also, and crucially, within-category words elicited smaller N400 amplitudes than between-category words. Federmeier and Kutas (1999) interpreted this gradation as suggesting that the ease with which a word (even if it is not expected) is accessed depends on its semantic similarity to the word expected in a given context (see also Federmeier et al (2002), for an extension in the auditory modality; Thornhill and Van Petten (2012)). …”

Testing the limits of the semantic illusion phenomenon: ERPs reveal temporary semantic change deafness in discourse comprehension

“…With spoken language comprehension, N400 effects typically begin to emerge at 150 -250 ms after acoustic onset of the critical word (e.g., [11,44,51]). This rapid onset is taken to reflect the immediacy with which every unfolding spoken word is routinely related to its semantic context.…”