A Rose by Any Other Name: Long-Term Memory Structure and Sentence Processing

Abstract

The effects of sentential context and semantic memory structure during on-line sentence processing were examined by recording event-related brain potentials as individuals read pairs of sentences for comprehension. The first sentence established an expectation for a particular exemplar of a semantic category, while the second ended with (1) that expected exemplar, (2) an unexpected exemplar from the same (expected) category, or (3) an unexpected item from a different (unexpected) category. Expected endings elicited a positivity between 250 and 550 ms while all unexpected endings elicited an N400, which was significantly smaller to items from the expected category. This N400 reduction varied with the strength of the contextually induced expectation: unexpected, categorically related endings elicited smaller N400s in more constraining contexts, despite their poorer fit to context (lower plausibility). This pattern of effects is best explained as reflecting the impact of context-independent long-term memory structure on sentence processing. The results thus suggest that physical and functional similarities that hold between objects in the world-i.e., category structure-influence neural organization and, in turn, routine language comprehension processes.

Electrophysiological insights into conceptual disorganization in schizophrenia

“…N400 effects were broadly distributed over the scalp although largest medially and centrally, consistent with the distribution seen in previous N400 studies of word reading (Federmeier and Kutas, 1999;Kutas and Van Petten, 1994) (Target × Electrode interaction: F 50,1100 =9.86, p<0.0001). There was no Group effect (F 1,34 =0.01, p=0.99) on N400 amplitude, nor any Group × Target interaction (F 2,68 =0.23, p=0.80), indicating that patients and controls did not differ significantly in N400 amplitude to the different target types.…”

Meaning and modality: Influences of context, semantic memory organization, and perceptual predictability on picture processing.

“…We replicated these results. As was observed for word processing using the same stimuli (Federmeier & Kutas, 1999), contextually unexpected pictures in both highly and more weakly constraining contexts are associated with enhanced negativity (N400) 250 to 500 ms after stimulus onset relative to contextually expected pictures. We also extend these findings by showing that the processing of both words and pictures is influenced by semantic similarity, here defined along the lines of taxonomic category structure.…”

“…Stimuli were derived from those used in Federmeier and Kutas (1999). They consisted of 132 pairs of sentences, ending with three types of targets: (a) expected exemplars (items with the highest cloze probability in the sentence contexts), (b) within-category violations (contextually unexpected items derived from the same taxonomic category as the expected exemplar), and (c) between-category violations (contextually unexpected items derived from a different category than the expected exemplar).…”

Multiple effects of sentential constraint on word processing

“…Further, this pattern interacted with constraint: greater facilitation was found for these "within category violations" in strongly than in more weakly constraining sentences, an effect that went in the opposite direction from the rated plausibility of these words in their contexts. Federmeier and Kutas (1999b) interpreted their findings as providing support for the hypothesis that listeners use context information to actively prepare for -i.e., to predict -semantic features of upcoming items. Facilitation is then a function of both the strength of the prediction (which varies with constraint) and the amount of semantic overlap between the predicted word and the one actually presented (greater for within-category than for between-category violations).…”

“…Federmeier and Kutas (1999b) examined the effects of relatedness and constraint by recording ERPs to unexpected sentence final words that had greater or lesser degrees of semantic overlap with the most expected completion. In an attempt to control for the expectancy of the two unexpected ending types, both were designed to be implausible completions for the sentence pairs.…”