An Individual Differences Examination of the Relation between Reading Processes and Comprehension.

Previous research has generally focused on understanding individual variation in either on-line processing or off-line comprehension even though some theories explicitly link difficulty in processing to comprehension problems. The goal of the current study was to examine individual variation in performance both during on-line and off-line reading measures. A battery of psycholinguistic and cognitive tests was administered to community college and university students. In addition, participants read texts in an eye-tracker and answered comprehension questions about them. Multi-level modeling was used to determine the individual-difference factors that modulated the relation between word-level characteristics (e.g., length, frequency, surprisal) and fixation durations. The analyses showed that language experience, decoding, and WMC interacted with word characteristics to influence fixation durations, whereas language experience and reasoning predicted comprehension. The results suggest that individual variation in processing does not map directly to variation in comprehension as some theories predict.

Adaptation to Animacy Violations during Listening Comprehension.

The goal of this study was to examine adaptation to various types of animacy violations in cartoon-like stories. We measured the event-related potentials (ERPs) elicited by words at the beginning, middle, and end of four-sentence stories in order to examine adaptation over time to conflicts between stored word knowledge and context-derived meaning (specifically, to inanimate objects serving as main characters, as they might in a cartoon). The fourth and final sentence of each story contained a predicate that required either an animate or an inanimate subject. The results showed that listeners quickly adapted to stories in the Inanimate Noun conditions, consistent with previous research (Filik & Leuthold, 2008; Nieuwland & Van Berkum, 2006). They showed evidence of processing difficulty for animacy-requiring predicates in the Inanimate Noun conditions in Sentence 1, but the effect dissipated in Sentences 2 and 3. In Sentences 2 and 4, we measured ERPs at three critical points where it was possible to observe the influence of both context-based expectations and expectations from prior knowledge on processing. Overall, the pattern of results demonstrates how listeners flexibly adapt to unusual, conflict-ridden input, using previous context to generate expectations about upcoming input, but that current context is weighted appropriately in combination with expectations from background knowledge and prior language experience.

Word-Decoding Skill Interacts With Working Memory Capacity to Influence Inference Generation During Reading.

The aim of this study was to examine predictions derived from a proposal about the relation between word-decoding skill and working memory capacity, called verbal efficiency theory. The theory states that poor word representations and slow decoding processes consume resources in working memory that would otherwise be used to execute high-level comprehension processes, such as the generation of inferences. Previous research has yielded inconsistent findings about the importance of word decoding in adult readers, and the hypothesis has never been tested experimentally. Verbal efficiency theory was tested in this experiment by manipulating the difficulty of grapheme-phoneme conversion and assessing the extent to which readers made bridging inferences. Participants read two-sentence passages and then responded to lexical decision targets. Some of the passages required a bridging inference to integrate the first and second sentences. Decoding difficulty was manipulated such that the second sentence in some passages was written using pseudohomophones. Participants also received tasks to assess their working memory capacity and decoding ability. Inference priming was found in both the Standard American English and pseudohomophone contexts but was stronger in the former than in the latter. The advantage in priming for the Standard English relative to the pseudohomophone condition was predicted by an interaction between decoding skill and working memory capacity. Poor decoders who scored high on the span tests were less impaired by the pseudohomophone manipulation than were poor decoders who scored low on the tests. The results suggest that working memory capacity compensates for poor decoding skills even among proficient adult readers.

Sensitivity to Referential Ambiguity in Discourse: The Role of Attention, Working Memory, and Verbal Ability.

The establishment of reference is essential to language comprehension. The goal of this study was to examine listeners' sensitivity to referential ambiguity as a function of individual variation in attention, working memory capacity, and verbal ability. Participants listened to stories in which two entities were introduced that were either very similar (e.g., two oaks) or less similar (e.g., one oak and one elm). The manipulation rendered an anaphor in a subsequent sentence (e.g., oak) ambiguous or unambiguous. EEG was recorded as listeners comprehended the story, after which participants completed tasks to assess working memory, verbal ability, and the ability to use context in task performance. Power in the alpha and theta frequency bands when listeners received critical information about the discourse entities (e.g., oaks) was used to index attention and the involvement of the working memory system in processing the entities. These measures were then used to predict an ERP component that is sensitive to referential ambiguity, the Nref, which was recorded when listeners received the anaphor. Nref amplitude at the anaphor was predicted by alpha power during the earlier critical sentence: Individuals with increased alpha power in ambiguous compared with unambiguous stories were less sensitive to the anaphor's ambiguity. Verbal ability was also predictive of greater sensitivity to referential ambiguity. Finally, increased theta power in the ambiguous compared with unambiguous condition was associated with higher working-memory span. These results highlight the role of attention and working memory in referential processing during listening comprehension.

Graded expectations: Predictive processing and the adjustment of expectations during spoken language comprehension.

The goal of this study was to investigate the use of the local and global contexts for incoming words during listening comprehension. Local context was manipulated by presenting a target noun (e.g., "cake," "veggies") that was preceded by a word that described a prototypical or atypical feature of the noun (e.g., "sweet," "healthy"). Global context was manipulated by presenting the noun in a scenario that was consistent or inconsistent with the critical noun (e.g., a birthday party). Event-related potentials (ERPs) were examined at the feature word and at the critical noun. An N400 effect was found at the feature word, reflecting the effect of compatibility with the global context. Global predictability and the local feature word consistency interacted at the critical noun: A larger N200 was found to nouns that mismatched predictions when the context was maximally constraining, relative to nouns in the other conditions. A graded N400 response was observed at the critical noun, modulated by global predictability and feature consistency. Finally, post-N400 positivity effects of context updating were observed to nouns that were supported by one contextual cue (global/local) but were unsupported by the other. These results indicate that (1) incoming words that are compatible with context-based expectations receive a processing benefit; (2) when the context is sufficiently constraining, specific lexical items may be activated; and (3) listeners dynamically adjust their expectations when input is inconsistent with their predictions, provided that the inconsistency has some level of support from either the global or the local context.

Spared and impaired spoken discourse processing in schizophrenia: effects of local and global language context.

Individuals with schizophrenia are impaired in a broad range of cognitive functions, including impairments in the controlled maintenance of context-relevant information. In this study, we used ERPs in human subjects to examine whether impairments in the controlled maintenance of spoken discourse context in schizophrenia lead to overreliance on local associations among the meanings of individual words. Healthy controls (n = 22) and patients (n = 22) listened to short stories in which we manipulated global discourse congruence and local priming. The target word in the last sentence of each story was globally congruent or incongruent and locally associated or unassociated. ERP local association effects did not significantly differ between control participants and schizophrenia patients. However, in contrast to controls, patients only showed effects of discourse congruence when targets were primed by a word in the local context. When patients had to use discourse context in the absence of local priming, they showed impaired brain responses to the target. Our findings indicate that schizophrenia patients are impaired during discourse comprehension when demands on controlled maintenance of context are high. We further found that ERP measures of increased reliance on local priming predicted reduced social functioning, suggesting that alterations in the neural mechanisms underlying discourse comprehension have functional consequences in the illness.

The use of context in resolving syntactic ambiguity: Structural and semantic influences.

Verb bias facilitates parsing of temporarily ambiguous sentences, but it is unclear when and how comprehenders use probabilistic knowledge about the combinatorial properties of verbs in context. In a self-paced reading experiment, participants read direct object/sentential complement sentences. Reading time in the critical region was investigated as a function of three forms of bias: structural bias (the frequency with which a verb appears in direct object/sentential complement sentences), lexical bias (the simple co-occurrence of verbs and other lexical items), and global bias (obtained from norming data about the use of verbs with specific noun phrases). For reading times at the critical word, structural bias was the only reliable predictor. However, global bias was superior to structural and lexical bias at the post-critical word and for offline acceptability ratings. The results suggest that structural information about verbs is available immediately, but that context-specific, semantic information becomes increasingly informative as processing proceeds.

Hemispheric asymmetries in the perceptual representations of words.

The representation of words in sentences can involve the activation and integration of perceptual information. For example, readers who are asked to view pictures of objects relating to a word in a sentence are influenced by perceptual information in the sentence context-readers are faster to respond to a picture of a whole apple after reading, "There is an apple in the bag," than after reading, "There is an apple in the salad." The purpose of this study was to examine how the two cerebral hemispheres use perceptual information about words as a function of sentence context. Patients who had damage to the left or right hemisphere and age-matched control participants read sentences that described, but did not entail, the shape or state of an object. They then made recognition judgments to pictures that either matched or mismatched the perceptual form implied by the sentence. Responses and latencies were examined for a match effect -- faster and more accurate responses to pictures in the match than mismatch condition -- controlling for comprehension ability and lesion size. When comprehension ability and lesion size are properly controlled, left-hemisphere-damaged patients and control participants exhibited the expected match effect, whereas right-hemisphere-damaged participants showed no effect of match condition. These results are consistent with research implicating the right hemisphere in the representation of contextually relevant perceptual information.

The importance of knowledge in vivid text memory: an individual-differences investigation of recollection and familiarity.

The goal of this study was to examine how individual variation in readers' skills and, in particular, their background knowledge about a text are related to text memory. Recollection and familiarity estimates were obtained from remember and know judgments to text ideas. Recollection estimates to old items were predicted by readers' background knowledge, but not by other comprehension-related factors, such as word-decoding skill and working memory capacity. False alarms involving recollection of new items (inferences) were diminished as a function of verbal ability, working memory capacity, and reasoning but increased as a function of background knowledge. The results suggest that recollection indexes the reader's ability to construct a text representation in which text ideas are integrated with relevant domain knowledge. Moreover, these results highlight the importance of background knowledge in explaining individual variation in comprehension and memory for text.

Hemispheric differences in the activation of perceptual information during sentence comprehension.

Previous research has suggested that perceptual information about objects is activated during sentence comprehension [Zwaan, R. A., Stanfield, R. A., & Yaxley, R. H. (2002). Language comprehenders mentally represent the shapes of objects. Psychological Science, 13(2), 168-171]. The goal in the current study was to examine the role of the two hemispheres in the activation of such information. Participants read sentences that conveyed information about the shape of an object (e.g., the egg was in the pan versus the egg was in the carton) and then received a picture of the object that was either consistent or inconsistent with the shape implied by the sentence (e.g., a fried egg versus a whole egg). In Experiment 1, pictures were presented briefly in either the left-visual field or the right-visual field. Participants showed a mismatch effect, slower responses when the picture was inconsistent with the shape of the object implied by the sentence than when it was consistent, but only when the pictures appeared in the right-visual field (left hemisphere). In Experiment 2, the sentences were revised such that the shape of the object was described explicitly. Participants showed a mismatch effect in both visual fields. These findings suggest that the right hemisphere activates shape information during sentence comprehension when a shape description is explicit, whereas the left hemisphere activates such information both when the shape is described explicitly and when it is implied.

The representation of discourse in the two hemispheres: an individual differences investigation.

Two experiments were conducted to investigate discourse representation in the two cerebral hemispheres as a function of reading skill. We used a lateralized visual-field procedure to compare left hemisphere (LH) and right hemisphere (RH) sensitivity to different discourse relations in readers with varying skill levels. In Experiment 1, we investigated two levels of discourse representation in memory: (a) the propositional representation and (b) the discourse model. We found that all readers were sensitive to propositional relations in the LH. In contrast, sensitivity to propositional relations in the RH increased as a function of reading skill. In addition, reading skill was positively related to topic relations in the LH, whereas it was negatively in the RH. In Experiment 2, we investigated propositional relations of different distances and again found that all readers were sensitive to propositional relations in the LH, whereas sensitivity to propositional relations in the RH was negatively related to reading skill. In general, reading skill appears to be associated with left-lateralized discourse representations.

Comprehension in Proficient Readers: The Nature of Individual Variation.

Individual-difference research on reading comprehension is challenging because reader characteristics are as correlated with each other as they are with comprehension. This study was conducted to determine which abilities are central to explaining comprehension and which are secondary to other abilities. A battery of psycholinguistic and cognitive tests was administered to community college and university students. Seven constructs were identified: word decoding, working-memory capacity (WMC), general reasoning, verbal fluency, perceptual speed, inhibition, and language experience. Only general reasoning and language experience had direct effects; these two variables accounted for as much variance in comprehension as did the complete set. Direct effects of WMC and decoding were found only when general reasoning and language experience were deleted from the models. The authors question the need to include WMC in our theories of variability in adult reading comprehension and highlight the need to understand precisely how vocabulary facilitates comprehension.

Language context processing deficits in schizophrenia: The role of attentional engagement.

Individuals with schizophrenia exhibit problems in language comprehension that are most evident during discourse processing. We hypothesized that deficits in cognitive control contribute to these comprehension deficits during discourse processing, and investigated the underlying cognitive-neural mechanisms using EEG (alpha power) and ERPs (N400). N400 amplitudes to globally supported or unsupported target words near the end of stories were used to index sensitivity to previous context. ERPs showed reduced sensitivity to context in patients versus controls. EEG alpha-band activity was used to index attentional engagement while participants listened to the stories. We found that context effects varied with attentional engagement in both groups, as well as with negative symptom severity in patients. Both groups demonstrated trial-to-trial fluctuations in alpha. Relatively high alpha power was associated with compromised discourse processing in participants with schizophrenia when it occurred during any early portion of the story. In contrast, discourse processing was only compromised in controls when alpha was relatively high for longer segments of the stories. Our results indicate that shifts in attention from the story context may be more detrimental to discourse processing for participants with schizophrenia than for controls, most likely due to an impaired ability to benefit from global context.

Assessing text representations with recognition: The interaction of domain knowledge and text coherence.

Readers construct at least 2 interrelated mental representations when they comprehend a text: a textbase and a situation model. Two experiments were conducted with recognition memory to examine how domain knowledge and text coherence influence readers' textbase and situation-model representations. In Experiment 1, participants made remember-know judgments to text ideas. Knowledge and coherence interacted to influence remember judgments differently than know judgments. In Experiment 2, the authors used the process-dissociation procedure to obtain recollection and familiarity estimates. Knowledge and coherence interacted to influence recollection estimates but not familiarity estimates. The authors claim that recollection and familiarity can be used as markers of the different processes involved in constructing a textbase and a situation model.

The propositional structure of discourse in the two cerebral hemispheres.

Readers construct at least two interrelated representations when they comprehend a text: (a) a representation of the explicit ideas in a text and the relations among them (i.e., a propositional representation) and (b) a representation of the context or situation to which a text refers (i.e., a discourse model). In a recent study, found evidence that readers' representations were structured according to propositional relations, but only in the left hemisphere. Both hemispheres, however, appeared to represent contextually relevant semantic information. The goal in the current study was to examine further the organization of explicit text concepts in the two hemispheres. We used an item-priming-in-recognition paradigm in combination with a lateralized visual-field manipulation. We found evidence for a propositionally structured representation in the left hemisphere, that is, priming effects that reflected the linear distance between primes and targets in the propositional structure of passages. We also found that the right hemisphere represented explicit text concepts, but we found no evidence that these concepts were organized structurally. In a second experiment, we found our item priming effects reflected the representation of text information in memory and did not reflect lexical-semantic priming at test.

Cognitive Control of Episodic Memory in Schizophrenia: Differential Role of Dorsolateral and Ventrolateral Prefrontal Cortex.

BACKGROUND: Dorsal (DLPFC) and ventral (VLPFC) subregions in lateral prefrontal cortex play distinct roles in episodic memory, and both are implicated in schizophrenia. We test the hypothesis that schizophrenia differentially impairs DLPFC versus VLPFC control of episodic encoding. METHODS: Cognitive control was manipulated by requiring participants to encode targets and avoid encoding non-targets based upon stimulus properties of test stimuli. The more automatic encoding response (target versus non-target) was predicted to engage VLPFC in both groups. Conversely, having to overcome the prepotent encoding response (non-targets versus targets) was predicted to produce greater DLPFC activation in controls than in patients. Encoding occurred during event-related fMRI in a sample of 21 individuals with schizophrenia and 30 healthy participants. Scanning was followed by recognition testing outside the scanner. RESULTS: Patients were less successful differentially remembering target versus non-target stimuli, and retrieval difficulties correlated with more severe disorganized symptoms. As predicted, the target versus non-target contrast activated the VLPFC and correlated with retrieval success in both groups. Conversely, the non-target versus target contrast produced greater DLPFC activation in controls than in patients, and DLPFC activation correlated with performance only in controls. CONCLUSION: Individuals with schizophrenia can successfully engage the VLPFC to provide control over semantic encoding of individual items, but are specifically impaired at engaging the DLPFC to main context for task-appropriate encoding and thereby generate improved memory for target versus non-target items. This extends previous cognitive control models based on response selection tasks to the memory domain.

Memory for Star Trek: the role of prior knowledge in recognition revisited.

Prior studies have found robust knowledge effects on recall of text ideas but have seldom found comparable effects on recognition. This inconsistency was examined in light of recent research on the component processes that underlie recognition memory. Using the remember/know paradigm, the authors found that experts made more remember judgments than novices, but only in response to text ideas relevant to their domain of expertise. Using the process-dissociation procedure, the authors found knowledge effects on recollection estimates, but not on familiarity estimates. The authors contend that knowledge effects have been difficult to detect in recognition because knowledge primarily affects recollection, whereas familiarity gives rise to good performance even among novices.

Memory availability and referential access.

Most theories of coreference specify linguistic factors that modulate antecedent accessibility in memory; however, whether non-linguistic factors also affect coreferential access is unknown. Here we examined the impact of a non-linguistic generation task (letter transposition) on the repeated-name penalty, a processing difficulty observed when coreferential repeated names refer to syntactically prominent (and thus more accessible) antecedents. In Experiment 1, generation improved online (event-related potentials) and offline (recognition memory) accessibility of names in word lists. In Experiment 2, we manipulated generation and syntactic prominence of antecedent names in sentences; both improved online and offline accessibility, but only syntactic prominence elicited a repeated-name penalty. Our results have three important implications: first, the form of a referential expression interacts with an antecedent's status in the discourse model during coreference; second, availability in memory and referential accessibility are separable; and finally, theories of coreference must better integrate known properties of the human memory system.

Modeling Reader- and Text- Interactions During Narrative Comprehension: A Test of the Lexical Quality Hypothesis.

The goal of this study was to examine predictions derived from the Lexical Quality Hypothesis (Perfetti & Hart, 2002; Perfetti, 2007) regarding relations among word-decoding, working-memory capacity, and the ability to integrate new concepts into a developing discourse representation. Hierarchical Linear Modeling was used to quantify the effects of two text properties (length and number of new concepts) on reading times of focal and spillover sentences, with variance in those effects estimated as a function of individual difference factors (decoding, vocabulary, print exposure, and working-memory capacity). The analysis revealed complex, cross-level interactions that complement the Lexical Quality Hypothesis.

Effects of working memory span on processing of lexical associations and congruence in spoken discourse.

The goal of this study was to determine whether variability in working memory (WM) capacity and cognitive control affects the processing of global discourse congruence and local associations among words when participants listened to short discourse passages. The final, critical word of each passage was either associated or unassociated with a preceding prime word (e.g., "He was not prepared for the fame and fortune/praise"). These critical words were also either congruent or incongruent with respect to the preceding discourse context [e.g., a context in which a prestigious prize was won (congruent) or in which the protagonist had been arrested (incongruent)]. We used multiple regression to assess the unique contribution of suppression ability (our measure of cognitive control) and WM capacity on the amplitude of individual N400 effects of congruence and association. Our measure of suppression ability did not predict the size of the N400 effects of association or congruence. However, as expected, the results showed that high WM capacity individuals were less sensitive to the presence of lexical associations (showed smaller N400 association effects). Furthermore, differences in WM capacity were related to differences in the topographic distribution of the N400 effects of discourse congruence. The topographic differences in the global congruence effects indicate differences in the underlying neural generators of the N400 effects, as a function of WM. This suggests additional, or at a minimum, distinct, processing on the part of higher capacity individuals when tasked with integrating incoming words into the developing discourse representation.