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Scholarly Works (7 results)

  • Thesis
  • Peer Reviewed
UC San Diego Electronic Theses and Dissertations (2019)

Across cognitive systems, world knowledge allows individuals to organize raw sensation into meaningful experiences. Language processing is no exception—words cue world knowledge which can be rapidly brought to mind in real time. It stands to reason that how much and how well individuals know things will impact what each individual brings to mind during real-time comprehension; yet to date, models of real-time language processing have not taken this variability into account. We addressed this issue by studying a linguistically rich, yet constrained, popular domain—the fictional world of Harry Potter (HP), by J.K. Rowling. In a series of three studies, we recorded event-related brain potentials (ERPs) while young adults who varied in their knowledge of HP read sentences about HP “facts” and/or sentences describing general topics. As a measure of real-time knowledge retrieval, we focused on N400 amplitude, a brain potential with a centro-parietal maximum occurring ~250-500 ms post stimulus onset that is sensitive to factors impacting the ease of retrieval from semantic memory, with larger reductions in N400 (i.e., more positive-going N400 potentials) associated with greater ease of retrieval.

Across all three studies, we found that individuals’ domain knowledge of HP (assessed via an offline multiple-choice trivia quiz) was moderately-to-strongly correlated with average N400 brain potentials to contextually supported (i.e., accurate) words completing sentences about HP, but not to unsupported (inaccurate) endings, nor to N400 effects (i.e., difference ERPs) of more vs. less supported endings to sentences describing general topics (Experiments 1 and 3). Single-trial regression analyses pitting domain knowledge against participants’ reports of knowledge about each HP “fact” (i.e., whether or not they had known each fact ahead of reading it) revealed trial-level knowledge was a strong, but not the sole, predictor of N400 amplitudes to supported words (Experiment 2). Rather, even after accounting for trial-level knowledge reports, and especially when retrieval conditions were presumably more difficult (i.e., for trials reported as unknown by an individual or those generally less likely to be known across participants), N400 amplitudes were modulated by individuals’ domain knowledge of HP. We hypothesized that degree of domain knowledge might modulate real-time semantic retrieval by virtue of the differential organization of that information in semantic memory—for example, functionally organized around events and categories, as has been proposed more generally in the literature on expert knowledge.

In Experiment 3, we therefore manipulated the relationship between the final (critical) words of HP sentences and their sentence contexts according to these organizational structures. Critical words (each of which appeared across conditions) were supported continuations, unsupported/unrelated continuations, or unsupported continuations that were related via an HP-specific category to the supported ending or to the event/episode being described by the sentence context. Individuals with greater HP domain knowledge showed reduced N400 amplitudes not only to supported words, but also to unsupported but contextually related words (for both types of relationships), compared to the unsupported unrelated words. That is, domain knowledge systematically influenced the quick availability of functionally (categorically, event-based) related knowledge during written sentence comprehension.

Our results provide the first empirical demonstration that real-time retrieval of knowledge during reading is determined by how much information is known and which facts are readily available to an individual comprehender. Domain knowledge seems to influence implicit retrieval of (perhaps) partial information (Experiment 2) and the availability of relevant/related information (Experiment 3)—the very information that is needed to make sense of words in real time. We hypothesize that variation in domain knowledge leads to systematic variation in hallmark organizational structures of semantic memory, including organization of categories and events, which in turn influence the degree to which relevant information can be (pre-)activated in order to make sense of words in real time.

    Cover page: Muggle or magical?: Electrophysiological investigations of variation in the language-knowledge interface during reading
    • Article
    • Peer Reviewed
    Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 42 (2020)
    How does individual-level variation in experience andknowledge influence neural mechanisms recruited during real-time language comprehension? We used event-related brainpotentials (ERPs) combined with lateralized visualpresentations of critical sentence-final words to examineasymmetries in hemispheric processing as individuals whovaried in their knowledge of the fictional world of Harry Potter(HP) read sentences about general topics / HP. HP sentenceendings were either contextually supported, unrelatedanomalies, or semantically related anomalies. Amongst HP“experts,” both hemispheres were sensitive to contextualsupport, but only the right hemisphere (RH) was sensitive tothe related anomaly manipulation. The exact pattern of resultsdepended on the relationship (categorical vs event). Ourfindings are in line with accounts on which the left hemisphere(LH) activates narrow/specific semantic contents and the RHactivates a broader range. We tentatively hypothesize thatcontent experts may exploit these hemispheric differences inscope of activation.
      Cover page: Hemispheric asymmetries in “expert” processingof semantic relationships during readingCreative Commons 'BY' version 4.0 license
      • Article
      • Peer Reviewed
      Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 37 (2015)
      Childhood socioeconomic status (SES) has a broad impact on cognitive development including nearly every aspect of language ability. In infancy, lower SES is associated with delays in real-time language processing skills, but it is not known whether or how this relationship carries into adulthood. We explore these questions by assessing the timecourse of anticipatory sentence interpretation in a visual-world eye-tracking task in college-aged adults from higher and lower SES backgrounds. While there were only subtle SES-related timing differences in anticipation of a sentence-final target noun, we found SES-related differences in looks to competitor items on the screen. Particularly, individuals from higher SES backgrounds showed relatively more looks to action-related competitors just prior to onset of the target noun. These findings suggest that early SES influences the dynamics of lexical activation during sentence processing even in adulthood and highlight the importance of early lexical input and experience for adult language skill
        Cover page: Childhood SES affects anticipatory language comprehension in college-aged adults
        • Article
        • Peer Reviewed
        Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 39 (2017)
        Real-time sentence processing involves connecting linguistic inputwith knowledge. Here, we ask how variability in semantic memory(specific domain knowledge) may influence semantic access in real-time sentence processing. We recorded EEG while participantsmore/less knowledgeable about the narrative world of Harry Potter(HP) read sentences. In Experiment 1, all participants showed N400predictability effects for general-knowledge sentences, but onlythose with high HP knowledge showed predictability effects forsentences about Harry Potter. This effect was driven by graded brainresponses to predictable endings as a function of knowledge.Experiment 2 revealed greater semantic activation (inferred fromN400 effects) for HP items participants reported knowing. High-knowledge participants also showed greater semantic activation foritems they reported not knowing/remembering. These findingssuggest that amount and/or functional organization of knowledgehas real-time consequences on written sentence processing andimplicate implicit/partial access to domain knowledge for expertswhen information is not explicitly recalled.
          Cover page: It’s all in your head: Effects of expertise on real-time accessto knowledge during written sentence processing
          • Article
          • Peer Reviewed
          UC San Diego Previously Published Works (2016)
          Language comprehension requires access to stored knowledge and the ability to combine knowledge in new, meaningful ways. Previous work has shown that processing linguistically more complex expressions ('Texas cattle rancher' vs. 'rancher') leads to slow-downs in reading during initial processing, possibly reflecting effort in combining information. Conversely, when this information must subsequently be retrieved (as in filler-gap constructions), processing is facilitated for more complex expressions, possibly because more semantic cues are available during retrieval. To follow up on this hypothesis, we tested whether information distributed across a short discourse can similarly provide effective cues for retrieval. Participants read texts introducing two referents (e.g., two senators), one of whom was described in greater detail than the other (e.g., 'The Democrat had voted for one of the senators, and the Republican had voted for the other, a man from Ohio who was running for president'). The final sentence (e.g., 'The senator who the {Republican/Democrat}had voted for…') contained a relative clause picking out either the Many-Cue referent (with 'Republican') or the One-Cue referent (with 'Democrat'). We predicted facilitated retrieval (faster reading times) for the Many-Cue condition at the verb region ('had voted for'), where readers could understand that 'The senator' is the object of the verb. As predicted, this pattern was observed at the retrieval region and continued throughout the rest of the sentence. Participants also completed the Author/Magazine Recognition Tests (ART/MRT; Stanovich and West, 1989), providing a proxy for world knowledge. Since higher ART/MRT scores may index (a) greater experience accessing relevant knowledge and/or (b) richer/more highly structured representations in semantic memory, we predicted it would be positively associated with effects of elaboration on retrieval. We did not observe the predicted interaction between ART/MRT scores and Cue condition at the retrieval region, though ART/MRT interacted with Cue condition in other locations in the sentence. In sum, we found that providing more elaborative information over the course of a text can facilitate retrieval for referents, consistent with a framework in which referential elaboration over a discourse and not just local linguistic information directly impacts information retrieval during sentence processing.
            Cover page: Elaboration over a Discourse Facilitates Retrieval in Sentence Processing
            • Article
            • Peer Reviewed
            Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 33 (2011)
              Cover page: Storage and computation in syntax: Evidence from relative clause priming
              • Article
              • Peer Reviewed
              UC San Diego Previously Published Works (2014)
              Language comprehension requires rapid and flexible access to information stored in long-term memory, likely influenced by activation of rich world knowledge and by brain systems that support the processing of sensorimotor content. We hypothesized that while literal language about biological motion might rely on neurocognitive representations of biological motion specific to the details of the actions described, metaphors rely on more generic representations of motion. In a priming and self-paced reading paradigm, participants saw video clips or images of (a) an intact point-light walker or (b) a scrambled control and read sentences containing literal or metaphoric uses of biological motion verbs either closely or distantly related to the depicted action (walking). We predicted that reading times for literal and metaphorical sentences would show differential sensitivity to the match between the verb and the visual prime. In Experiment 1, we observed interactions between the prime type (walker or scrambled video) and the verb type (close or distant match) for both literal and metaphorical sentences, but with strikingly different patterns. We found no difference in the verb region of literal sentences for Close-Match verbs after walker or scrambled motion primes, but Distant-Match verbs were read more quickly following walker primes. For metaphorical sentences, the results were roughly reversed, with Distant-Match verbs being read more slowly following a walker compared to scrambled motion. In Experiment 2, we observed a similar pattern following still image primes, though critical interactions emerged later in the sentence. We interpret these findings as evidence for shared recruitment of cognitive and neural mechanisms for processing visual and verbal biological motion information. Metaphoric language using biological motion verbs may recruit neurocognitive mechanisms similar to those used in processing literal language but be represented in a less-specific way.
                Cover page: Action verbs are processed differently in metaphorical and literal sentences depending on the semantic match of visual primes
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