Multiple mechanisms of visual prediction as revealed by the timecourse of scene-object facilitation

Not only semantic, but also recently learned arbitrary associations have the potential to facilitate visual processing in everyday life-for example, knowledge of a (moveable) object's location at a specific time may facilitate visual processing of that object. In our prior work, we showed that previewing a scene can facilitate processing of recently associated objects at the level of visual analysis (Smith and Federmeier in Journal of Cognitive Neuroscience, 32(5):783-803, 2020). In the current study, we assess how rapidly this facilitation unfolds by manipulating scene preview duration. We then compare our results to studies using well-learned object-scene associations in a first-pass assessment of whether systems consolidation might speed up high-level visual prediction. In two ERP experiments (N = 60), we had participants study categorically organized novel object-scene pairs in an explicit paired associate learning task. At test, we varied contextual pre-exposure duration, both between (200 vs. 2500 ms) and within subjects (0-2500 ms). We examined the N300, an event-related potential component linked to high-level visual processing of objects and scenes and found that N300 effects of scene congruity increase with longer scene previews, up to approximately 1-2 s. Similar results were obtained for response times and in a separate component-neutral ERP analysis of visual template matching. Our findings contrast with prior evidence that scenes can rapidly facilitate visual processing of commonly associated objects. This raises the possibility that systems consolidation might mediate different kinds of predictive processing with different temporal profiles.

The Impact of Linguistic Prediction Violations on Downstream Recognition Memory and Sentence Recall

Predicting upcoming words during language comprehension not only affects processing in the moment but also has consequences for memory, although the source of these memory effects (e.g., whether driven by lingering pre-activations, re-analysis following prediction violations, or other mechanisms) remains underspecified. Here, we investigated downstream impacts of prediction on memory in two experiments. First, we recorded EEG as participants read strongly and weakly constraining sentences with expected, unexpected but plausible, or semantically anomalous endings ("He made a holster for his gun / father / train") and were tested on their recognition memory for the sentence endings. Participants showed similar rates of false alarms for predicted but never presented sentence endings whether the prediction violation was plausible or anomalous, suggesting that these arise from pre-activation of the expected words during reading. During sentence reading, especially in strongly constraining sentences, plausible prediction violations elicited an anterior positivity; anomalous endings instead elicited a posterior positivity, whose amplitude was predictive of later memory for those anomalous words. ERP patterns at the time of recognition differentiated plausible and anomalous sentence endings: Words that had been plausible prediction violations elicited enhanced late positive complex amplitudes, suggesting greater episodic recollection, whereas anomalous sentence endings elicited greater N1 amplitudes, suggesting attentional tagging. In a follow-up behavioral study, a separate group of participants read the same sentence stimuli and were tested for sentence-level recall. We found that recall of full sentences was impaired when sentences ended with a prediction violation. Taken together, the results suggest that prediction violations draw attention and affect encoding of the violating word, in a manner that depends on plausibility, and that this, in turn, may impair future memory of the gist of the sentence.

Graded and ungraded expectation patterns: Prediction dynamics during active comprehension

Language comprehension can be facilitated by the accurate prediction of upcoming words, but prediction effects are not ubiquitous, and comprehenders likely use predictive processing to varying degrees depending on task demands. To ascertain the processing consequences of prioritizing prediction, we here compared ERPs elicited when young adult participants simply read for comprehension with those collected in a subsequent block that required active prediction. We were particularly interested in frontally-distributed post-N400 effects for expected and unexpected words in strongly constraining contexts, which have previously been documented as two distinct patterns: an enhanced positivity ("anterior positivity") observed for prediction violations compared to words that are merely unpredictable (because they occur in weakly constraining sentences) and a distinction between expected endings in more constraining contexts and those same weakly constrained words ("frontal negativity" to the strongly predicted words). We found that the size of the anterior positivity effect was unchanged between passive comprehension and active prediction, suggesting that some processes related to prediction may engage state-like networks. On the other hand, the frontal negativity showed graded patterns from the interaction of task and sentence type. These differing patterns support the hypothesis that there are two separate effects with frontal scalp distributions that occur after the N400 and further suggest that the impact of violating predictions (as long as prediction is engaged at all) is largely stable across varying levels of effort/attention directed toward prediction, whereas other comprehension processes can be modulated by task demands.

Emotional dissociations in temporal associations: opposing effects of arousal on memory for details surrounding unpleasant events

Research targeting emotion's impact on relational episodic memory has largely focused on spatial aspects, but less is known about emotion's impact on memory for an event's temporal associations. The present research investigated this topic. Participants viewed a series of interspersed negative and neutral images with instructions to create stories linking successive images. Later, participants performed a surprise memory test, which measured temporal associations between pairs of consecutive pictures where one picture was negative and one was neutral. Analyses focused on how the order of negative and neutral images during encoding influenced retrieval accuracy. Converging results from a discovery study (N = 72) and pre-registered replication study (N = 150) revealed a "forward-favouring" effect of emotion in temporal memory encoding: Participants encoded associations between negative stimuli and subsequent neutral stimuli more strongly than associations between negative stimuli and preceding neutral stimuli. This finding may reflect a novel trade-off regarding emotion's effects on memory and is relevant for understanding affective disorders, as key clinical symptoms can be conceptualised as maladaptive memory retrieval of temporal details.

Virtual Reality Sickness Reduces Attention During Immersive Experiences

In this paper, we show that Virtual Reality (VR) sickness is associated with a reduction in attention, which was detected with the P3b Event-Related Potential (ERP) component from electroencephalography (EEG) measurements collected in a dual-task paradigm. We hypothesized that sickness symptoms such as nausea, eyestrain, and fatigue would reduce the users' capacity to pay attention to tasks completed in a virtual environment, and that this reduction in attention would be dynamically reflected in a decrease of the P3b amplitude while VR sickness was experienced. In a user study, participants were taken on a tour through a museum in VR along paths with varying amounts of rotation, shown previously to cause different levels of VR sickness. While paying attention to the virtual museum (the primary task), participants were asked to silently count tones of a different frequency (the secondary task). Control measurements for comparison against the VR sickness conditions were taken when the users were not wearing the Head-Mounted Display (HMD) and while they were immersed in VR but not moving through the environment. This exploratory study shows, across multiple analyses, that the effect mean amplitude of the P3b collected during the task is associated with both sickness severity measured after the task with a questionnaire (SSQ) and with the number of counting errors on the secondary task. Thus, VR sickness may impair attention and task performance, and these changes in attention can be tracked with ERP measures as they happen, without asking participants to assess their sickness symptoms in the moment.

Older Adults Show Intraindividual Variation in the Use of Predictive Processing

BACKGROUND

The use of prediction can aid language comprehension through preactivation of relevant word features. However, predictions can be wrong, and it has been proposed that resolving the mismatch between the predicted and presented item requires cognitive resources. Older adults tend not to predict and instead rely more on passive comprehension. Here, we tested, using an intraindividual approach, whether older adults consistently use this less demanding processing strategy while reading or whether they attempt to predict on some trials.

METHODS

We used a cross-task conflict paradigm. Younger and older participants self-paced to read sentences that ended with either an expected or unexpected word. Each sentence was then followed by a flanker stimulus that could be congruent or incongruent. We examined responses within and across the two tasks.

RESULTS

Unexpected words were in general read as quickly as expected words, indicating that typical processing of these words was similar. However, for both younger and older adults, there was a greater proportion of very slow trials for unexpected words, revealing different processing on a subset of trials. Critically, in older adults, these slowly read unexpected words engaged control, as seen in speeded responses to incongruent flanker stimuli.

CONCLUSION

Using a cross-task conflict paradigm, we showed that older adults are able to predict and engage cognitive resources to cope with prediction violations, but do not opt to use these processes consistently.

Read carefully, because this is important! How value-driven strategies impact sentence memory

Little is understood about how people strategically process and remember important but complex information, such as sentences. In the current study, we asked whether people can effectively prioritize memory for sentences as a function of their relative importance (operationalized as a reward point value) and whether they do so, in part, by changing their sentence processing strategies when value information is available in advance. We adapted the value-directed remembering paradigm (Castel, Psychol Learn Motiv 48:225-270, 2007) for sentences that varied in constraint and predictability. Each sentence was associated with a high or low value for subsequent free recall (whole sentence) and recognition (sentence-final words) tests. Value information appeared after or before each sentence as a between-subject manipulation. Regardless of condition, we observed that high-value sentences were recalled more often than low-value sentences, showing that people can strategically prioritize their encoding of sentences. However, memory patterns differed depending on when value information was available. Recall for high-value sentences that ended unexpectedly (and therefore violated one's predictions) was reduced in the Before compared to the After condition. Before condition participants also showed a greater tendency to false alarm to lures (words that were the predicted - but not obtained - ending) from strongly constraining sentences. These observations suggest that when people try to prioritize sentence-level information that they know is valuable, the reading strategies they employ may paradoxically lead to worse memory.

Patterns of hemispheric asymmetry provide evidence dissociating the semantic and syntactic P600

To understand how neural networks in the left (LH) and right (RH) cerebral hemispheres contribute to different aspects of language comprehension, in two experiments we measured event-related potentials (ERPs) as right-handed participants read sentences, some of which contained morphosyntactic and thematic role violations. Replicating prior work (Kuperberg et al., 2006), in Experiment 1 thematic role violations elicited both an N400 and a (semantic) P600 effect. Morphosyntactic violations elicited effects that differed as a function of participants' familial sinistrality (the presence [FS+] or absence [FS-] of a left-handed biological relative): FS+ participants showed a (syntactic) P600 effect whereas FS- participants showed a biphasic N400 and P600 response. To assess whether this difference reflects different underlying patterns of lateralization, in Experiment 2 target words were presented using visual half-field (VF) presentation. Indeed, for morphosyntactic violations, the FS- group elicited an asymmetric pattern, showing a P600 effect only with LH-biased presentation and an N400 effect in both VFs (cf. Lee and Federmeier, 2015). In contrast, FS+ participants showed a bilateral (N400-only) response pattern. This provides further evidence of FS-based differences in hemispheric contributions to syntactic processing. Strikingly, we found that, when lateralized, thematic role violations did not elicit a P600 effect, suggesting that this effect requires contributions from both hemispheres. The different response patterns for morphosyntactic and thematic role animacy violations across FS and VF also point to a processing difference in the comprehension mechanisms underlying the semantic and syntactic P600, which had heretofore been assumed to be variants of the same component.

The effect of acute alcohol intoxication on alcohol cue salience: An event-related brain potential study

OBJECTIVE

Alcohol cue salience is considered core to the broader understanding of drinking behaviors. In the present research, we sought to build the knowledge of alcohol cue salience by exploring P3 responses to alcohol images among social drinkers within a large-scale alcohol-administration study.

METHOD

Participants (N = 246) were randomly assigned to receive either a moderate dose of alcohol (target BAC = .08%) or a nonalcoholic control beverage. Following beverage administration, participants engaged in image-viewing tasks while EEG was recorded. We examined the impact of alcohol on the amplitude of P3 responses to pictures of alcoholic versus nonalcoholic beverages, exploring both beverage-manipulation and individual-difference moderators of these effects.

RESULTS

Results revealed a significant effect of acute alcohol intoxication on P3 responses across stimulus types, with the overall amplitude of P3 being significantly smaller among participants consuming alcohol versus a nonalcoholic beverage. In addition, results revealed a significant main effect of image type, such that P3 amplitude was larger for alcohol images compared to nonalcohol images. No interactions emerged between stimulus type and beverage condition or stimulus type and AUD risk level.

CONCLUSIONS

With the aim of better understanding the potential influence of the broader context on responses to individual cues, the present study examined the perceived salience of alcohol cues within a drinking setting. Findings provide evidence for alcohol cue salience that is both robust and also widespread across drinkers. More generally, the present study's findings may offer new directions for understanding neurocognitive processes of alcohol cue salience across contexts. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The last course of coarse coding: Hemispheric similarities in associative and categorical semantic processing

To test theories that posit differences in how semantic information is represented in the cerebral hemispheres, we assessed semantic priming for associatively and categorically related prime-target pairs that were graded in relatedness strength. Visual half-field presentation was used to bias processing to the right or left hemisphere, and event-related potential (ERP) and behavioral responses were measured while participants completed a semantic relatedness judgement task. Contrary to theories positing representational differences across the cerebral hemispheres, in two experiments using (1) centralized prime presentation and lateralized targets and (2) lateralized primes and targets, we found similar priming patterns across the two hemispheres at the level of semantic access (N400), on later measures of explicit processing (late positive complex; LPC), and in behavioral response speeds and accuracy. We argue that hemispheric differences, when they arise, are more likely due to differences in task demands than in how the hemispheres fundamentally represent semantic information.

Context-based facilitation of semantic access follows both logarithmic and linear functions of stimulus probability

Stimuli are easier to process when context makes them predictable, but does context-based facilitation arise from preactivation of a limited set of relatively probable upcoming stimuli (with facilitation then linearly related to probability) or, instead, because the system maintains and updates a probability distribution across all items (with facilitation logarithmically related to probability)? We measured the N400, an index of semantic access, to words of varying probability, including unpredictable words. Word predictability was measured using both cloze probabilities and a state-of-the-art machine learning language model (GPT-2). We reanalyzed five datasets (n = 138) to demonstrate and then replicate that context-based facilitation on the N400 is graded, even among unpredictable words. Furthermore, we established that the relationship between word predictability and context-based facilitation combines linear and logarithmic functions. We argue that this composite function reveals properties of the mapping between words and semantic features and how feature- and word-related information is activated on-line.

Age-related Changes in the Structure and Dynamics of the Semantic Network

Normal aging has variable effects on language comprehension, perhaps because comprehension mechanisms vary in their dependence on network structure versus network dynamics. To test claims that processing dynamics are more affected by age than structure, we used EEG to measure and compare the impact of neighborhood size, a core measure of the structure of the lexico-semantic network, and repetition, a simple measure of processing dynamics, on single word processing. Older adults showed robust effects of neighborhood size on the N400, comparable to those elicited by young adults, but reduced effects of repetition. Furthermore, older adults with greater verbal fluency, print exposure, and reading comprehension showed greater repetition effects, suggesting some older adults can maintain processing dynamics that are similar to those of young adults. Thus, the organizational structure of the semantic network seems stable across normal aging, but (some) older adults may struggle to adjust activation states within that network.

Connecting and considering: Electrophysiology provides insights into comprehension

The ability to rapidly and systematically access knowledge stored in long-term memory in response to incoming sensory information-that is, to derive meaning from the world-lies at the core of human cognition. Research using methods that can precisely track brain activity over time has begun to reveal the multiple cognitive and neural mechanisms that make this possible. In this article, I delineate how a process of connecting affords an effortless, continuous infusion of meaning into human perception. In a relatively invariant time window, uncovered through studies using the N400 component of the event-related potential, incoming sensory information naturally induces a graded landscape of activation across long-term semantic memory, creating what might be called "proto-concepts". Connecting can be (but is not always) followed by a process of further considering those activations, wherein a set of more attentionally demanding "active comprehension" mechanisms mediate the selection, augmentation, and transformation of the initial semantic representations. The result is a limited set of more stable bindings that can be arranged in time or space, revised as needed, and brought to awareness. With this research, we are coming closer to understanding how the human brain is able to fluidly link sensation to experience, to appreciate language sequences and event structures, and, sometimes, to even predict what might be coming up next.

Direct feedback and social conformity promote behavioral change via mechanisms indexed by centroparietal positivity: Electrophysiological evidence from a role-swapping ultimatum game

Our behavior is shaped by multiple factors, including direct feedback (seeing the outcomes of our past actions) and social observation (in part, via a drive to conform to other peoples' behaviors). However, it remains unclear how these two processes are linked in the context of behavioral change. This is important to investigate, as behavioral change is associated with distinct neural correlates that reflect specific aspects of processing, such as information integration and rule updating. To clarify whether these processes characterize both direct learning and conformity, we elicited the two within the same task, using a role-swapping version of the Ultimatum Game-a fairness paradigm where subjects decide how to share a pot of money with other players-while electroencephalography (EEG) data were recorded. Behavioral results showed that subjects decided how to divide the pot based on both direct feedback (seeing whether their past proposals were accepted or rejected) and social observation (copying the splits that others just proposed). Converging EEG evidence revealed that increased centroparietal positivity (P2, P3b, and late positivity) indexed behavioral changes motivated by direct feedback and those motivated by drives to conform. However, exploratory analyses also suggest that these two motivating factors may also be dissociable, and that frontal midline theta oscillations may predict behavioral changes linked to direct feedback but not conformity. Overall, this study provides novel electrophysiological evidence regarding the different forms of behavioral change. These findings are also relevant for understanding the mechanisms of social information processing that underlie successful cooperation.

The power of "good": Can adjectives rapidly decrease as well as increase the availability of the upcoming noun?

Can a single adjective immediately influence message-building during sentence processing? We presented participants with 168 sentence contexts, such as "His skin was red from spending the day at the …" Sentences ended with either the most expected word ("beach") or a low cloze probability completion ("pool"). Nouns were preceded by adjectives that changed their relative likelihood (e.g., "neighborhood" increases the cloze probability of pool whereas "sandy" promotes beach). We asked if participants' online processing can be rapidly updated by the adjective, changing the resulting pattern of facilitation at the noun, and, if so, whether updates unfold symmetrically-not only increasing, but also decreasing, the fit of particular nouns. We measured event-related potentials (ERPs) to the adjective and the noun and modeled these with respect to (a) the overall amount of updating promoted by the adjective, (b) the preadjectival cloze probability of the noun and, (c) the amount of cloze probability change for the obtained noun after the adjective. Bayesian mixed-effects analysis of N400 amplitude at the noun revealed that adjectives rapidly influenced semantic processing of the noun, but did so asymmetrically, with positive updating (reducing N400 amplitudes) having a greater effect than negative updating (increasing N400s). At the adjective, the amount of (possible) updating was not associated with any discernible ERP modulation. Overall, these results suggest the information provided by adjectives is buffered until a head noun is encountered, at which point the access of the noun's semantics is shaped in parallel by both the adjective and the sentence-level representation. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Representational Pattern Similarity of Electrical Brain Activity Reveals Rapid and Specific Prediction during Language Comprehension

Predicting upcoming events is a critical function of the brain, and language provides a fertile testing ground for studying prediction, as comprehenders use context to predict features of upcoming words. Many aspects of the mechanisms of prediction remain elusive, partly due to a lack of methodological tools to probe prediction formation in the moment. To elucidate what features are neurally preactivated and when, we used representational similarity analysis on previously collected sentence reading data. We compared EEG activity patterns elicited by expected and unexpected sentence final words to patterns from the preceding words of the sentence, in both strongly and weakly constraining sentences. Pattern similarity with the final word was increased in an early time window following the presentation of the pre-final word, and this increase was modulated by both expectancy and constraint. This was not seen at earlier words, suggesting that predictions were precisely timed. Additionally, pre-final word activity-the predicted representation-had negative similarity with later final word activity, but only for strongly expected words. These findings shed light on the mechanisms of prediction in the brain: rapid preactivation occurs following certain cues, but the predicted features may receive reduced processing upon confirmation.

The N300: An Index for Predictive Coding of Complex Visual Objects and Scenes

Predictive coding models can simulate known perceptual or neuronal phenomena, but there have been fewer attempts to identify a reliable neural signature of predictive coding for complex stimuli. In a pair of studies, we test whether the N300 component of the event-related potential, occurring 250–350-ms poststimulus-onset, has the response properties expected for such a signature of perceptual hypothesis testing at the level of whole objects and scenes. We show that N300 amplitudes are smaller to representative (“good exemplars”) compared with less representative (“bad exemplars”) items from natural scene categories. Integrating these results with patterns observed for objects, we establish that, across a variety of visual stimuli, the N300 is responsive to statistical regularity, or the degree to which the input is “expected” (either explicitly or implicitly) based on prior knowledge, with statistically regular images evoking a reduced response. Moreover, we show that the measure exhibits context-dependency; that is, we find the N300 sensitivity to category representativeness when stimuli are congruent with, but not when they are incongruent with, a category pre-cue. Thus, we argue that the N300 is the best candidate to date for an index of perceptual hypotheses testing for complex visual objects and scenes.

Alcohol and Neural Dynamics: A Meta-analysis of Acute Alcohol Effects on Event-Related Brain Potentials

BACKGROUND

An understanding of alcohol's acute neural effects could augment our knowledge of mechanisms underlying alcohol-related cognitive/motor impairment and inform interventions for addiction. Focusing on studies employing event-related brain potential methods, which offer a direct measurement of neural activity in functionally well-characterized brain networks, we present the first meta-analysis to explore acute effects of alcohol on the human brain.

METHODS

Databases were searched for randomized laboratory alcohol-administration trials assessing brain activity using event-related potentials. Hedges' g coefficients were pooled using 3-level random-effects meta-regression.

RESULTS

Sixty independent randomized controlled trials met inclusion (total N = 2149). Alcohol's effects varied significantly across neural systems, with alcohol leading to reductions in event-related potential components linked with attention (P3b), g = -0.40, 95% CI (-0.50, -0.29), automatic auditory processing (mismatch negativity), g = -0.44, 95% CI (-0.66, -0.22), and performance monitoring (error-related negativity), g = -0.56, 95% CI (-0.79, -0.33). These effects were moderated by alcohol dose, emerging as significant at doses as low as 0.026% blood alcohol concentration and increasing to moderate/large at 0.12%. In contrast, irrespective of dose, relatively small or nonsignificant alcohol effects emerged in other processing domains, including those linked to executive control (N2b responses) and stimulus classification (N2c responses).

CONCLUSIONS

Contrary to traditional conceptualizations of alcohol as a "dirty drug" with broad central nervous system depressant effects, results instead support accounts positing targeted alcohol effects in specific processing domains. By identifying alcohol effects on brain systems involved in performance monitoring and attention, results move toward the identification of mechanisms underlying alcohol-related impairment as well as factors reinforcing addiction.

Dividing attention influences contextual facilitation and revision during language comprehension

Although we often seem to successfully comprehend language in the face of distraction, few studies have examined the role of sustained attention in critical components of sentence processing, such as integrating information over a sentence and revising predictions when unexpected information is encountered. The current study investigated the impact of attention on sentence processing using a novel dual-task paradigm. Participants read weakly and strongly constraining sentences with expected or unexpected endings while also tracking the motion of dots in the background, and their EEG was recorded. Under full attention, the amplitude of the N400 component of the ERP, a measure of semantic access, was reduced (facilitated) in a graded fashion by contextual strength and fit. This context-based facilitation was attenuated when attention was divided, suggesting that sustained attention is important for building up message-level representations. In contrast, the post-N400 frontal positivity that has been observed to prediction violations and associated with revision processes was unaffected by dividing attention. However, under divided attention, participants also elicited posteriorly-distributed effects to these violations. Thus, predictive processes seem to be engaged even when attention is divided, but additional resources may then be required to process unexpected information.

The fate of the unexpected: Consequences of misprediction assessed using ERP repetition effects

Amid increasing interest in the role of prediction in language comprehension, there remains a gap in our understanding of what happens when predictions are disconfirmed. Are unexpected words harder to process and encode because of interference from the original prediction? Or, because of their relevance for learning, do expectation violations strengthen the representations of unexpected words? In two experiments, we used event-related potentials to probe the downstream consequences of prediction violations. Critical words were unexpected but plausible completions of either strongly constraining sentences, wherein they constituted a prediction violation, or weakly constraining sentences that did not afford a clear prediction. Three sentences later the critical word was repeated at the end of a different, weakly constraining sentence. In Experiment 1, repeated words elicited a reduced N400 and an enhanced late positive complex (LPC) compared to words seen for the first time. Critically, there was no effect of initial sentence constraint on the size of the repetition effect in either time window. Thus, prediction violations did not accrue either costs or benefits for later processing. Experiment 2 used the same critical items and added strongly constraining filler sentences with expected endings to further promote prediction. Again, there was no effect of initial sentence constraint on either the N400 or the LPC to repeated critical words. When taken with prior findings, the results suggest that prediction is both powerful and flexible: It can facilitate processing of predictable information by reducing encoding effort without causing processing difficulties for unexpected inputs.

Inter- and intra-individual coupling between pupillary, electrophysiological, and behavioral responses in a visual oddball task

Although the P3b component of the event-related brain potential is one of the most widely studied components, its underlying generators are not currently well understood. Recent theories have suggested that the P3b is triggered by phasic activation of the locus-coeruleus norepinephrine (LC-NE) system, an important control center implicated in facilitating optimal task-relevant behavior. Previous research has reported strong correlations between pupil dilation and LC activity, suggesting that pupil diameter is a useful indicator for ongoing LC-NE activity. Given the strong relationship between LC activity and pupil dilation, if the P3b is driven by phasic LC activity, there should be a robust trial-to-trial relationship with the phasic pupillary dilation response (PDR). However, previous work examining relationships between concurrently recorded pupillary and P3b responses has not supported this. One possibility is that the relationship between the measures might be carried primarily by either inter-individual (i.e., between-participant) or intra-individual (i.e., within-participant) contributions to coupling, and prior work has not systematically delineated these relationships. Doing so in the current study, we do not find evidence for either inter-individual or intra-individual relationships between the PDR and P3b responses. However, baseline pupil dilation did predict the P3b. Interestingly, both the PDR and P3b independently predicted inter-individual and intra-individual variability in decision response time. Implications for the LC-P3b hypothesis are discussed.

Examining the Role of General Cognitive Skills in Language Processing: A Window into Complex Cognition

Whenever we use language to communicate, sounds, signs, and/or letters are combined into words that, in turn, form sentences, which together tell a story. Both language production and language comprehension rely on representations at different levels of granularity that need to be continuously and rapidly activated, selected, and combined. The representations themselves are specific to language, but many processes that regulate their use, such as inhibition of competitors or updating of working memory with new information, are so-called domain-general abilities that apply across different kinds of tasks. Here, we provide an overview of the behavioral and neurophysiological evidence in favor of domain-general abilities underpinning language skills and describe which particular aspects of production and comprehension draw upon such cognitive resources. We discuss how this line of research not only reveals important similarities between production and comprehension but also helps to establish links between language and other cognitive domains. Finally, we argue that studying how domain-general abilities are used in language will lead to important insights into the highly dynamic and efficient communication between brain networks that is necessary to successfully go from sounds to stories.

Literacy skill and intra-individual variability in eye-fixation durations during reading: Evidence from a diverse community-based adult sample

To understand the effects of literacy on fundamental processes involved in reading, we report a secondary data analysis examining individual differences in global eye-movement measures and first-pass eye-movement distributions in a diverse sample of community-dwelling adults aged 16 to 64. Participants (n = 80) completed an assessment battery probing verbal and non-verbal cognitive abilities and read simple two-sentence passages while their eye movements were recorded. Analyses were focused on characterising the effects of literacy skill on both global indices of eye-fixation distributions and distributional differences in the sensitivity to lexical features. Global reading measures showed that lower literate adults read more slowly on average. However, distributional analyses of fixation durations revealed that the first-pass fixation durations of adults with lower literacy skill were not slower in general (i.e., there was no shift in the fixation duration distribution among lower literate adults). Instead, lower literacy was associated with greater intra-individual variability in first-pass fixation durations, including an increased proportion of extremely long fixations, differentially skewing the distribution of both first-fixation and gaze durations. Exploratory repeated-measures quantile regression analyses of gaze duration revealed differentially greater influences of word length among lower literate readers and greater activation of phonological and orthographic neighbours among higher literate readers, particularly in the tail of the distribution. Collectively, these findings suggest that literacy skill in adulthood is associated with systematic differences in both global and lexically driven eye-movement control during reading.

Neural Signatures of Learning Novel Object-Scene Associations

Objects are perceived within rich visual contexts, and statistical associations may be exploited to facilitate their rapid recognition. Recent work using natural scene-object associations suggests that scenes can prime the visual form of associated objects, but it remains unknown whether this relies on an extended learning process. We asked participants to learn categorically structured associations between novel objects and scenes in a paired associate memory task while ERPs were recorded. In the test phase, scenes were first presented (2500 msec), followed by objects that matched or mismatched the scene; degree of contextual mismatch was manipulated along visual and categorical dimensions. Matching objects elicited a reduced N300 response, suggesting visuostructural priming based on recently formed associations. Amplitude of an extended positivity (onset ∼200 msec) was sensitive to visual distance between the presented object and the contextually associated target object, most likely indexing visual template matching. Results suggest recent associative memories may be rapidly recruited to facilitate object recognition in a top-down fashion, with clinical implications for populations with impairments in hippocampal-dependent memory and executive function.

Individual Differences in Reading Speed are Linked to Variability in the Processing of Lexical and Contextual Information: Evidence from Single-trial Event-related Brain Potentials

In the current paper, we examined the effects of lexical (e.g. word frequency, orthographic neighborhood density) and contextual (e.g. word predictability in the form of cloze probability) features on single-trial event-related brain potentials in a self-paced reading paradigm. Critically, we examined whether individual differences in reading speed modulated single-trial effects on the N400, an ERP component linked to semantic memory access. Consistent with past work, we found that word frequency effects on the N400 were attenuated with increasing predictability. However, effects of orthographic neighborhood density were robust across all levels of predictability. Importantly, individual differences in reading speed moderated the influence of both frequency and predictability (but not orthographic neighborhood density) on the N400, such that slower readers showed reduced effects compared to faster readers. These data show that different lexical factors influence word processing through dissociable mechanisms. Our findings support a dynamic semantic-memory access model of the N400, in which information at multiple levels (lexical, sentential, individual) simultaneously contributes to the unfolding neural dynamics of comprehension.

Adult Age Differences in the Use of Conceptual Combination as an Associative Encoding Strategy

It is well-established that aging impairs memory for associations more than it does memory for single items. Aging also impacts processes involved in online language comprehension, including the ability to form integrated, message-level representations. These changes in comprehension processes could impact older adults’ associative memory performance, perhaps by reducing or altering the effectiveness of encoding strategies that encourage semantic integration. The present study examined age differences in the use of a strategy termed conceptual combination, which involves integrating two words (e.g., “winter” and “salad”) into a single concept (“a salad for winter”). We recorded ERPs while participants studied unrelated noun pairs using a strategy that either did or did not encourage conceptual combination. We also varied the concreteness of the first noun in each pair in order to measure compositional concreteness effects, or ERP differences at the second noun due to the concreteness of the first noun. At the first nouns, older adults showed word-level concreteness effects that were similar to those of younger adults. However, compositional concreteness effects were diminished in older adults, consistent with reduced semantic integration. Older adults’ associative memory performance was better for word pairs studied during the conceptual combination task versus the non-combinatory encoding task; however, the magnitude of the age-related associative memory deficit did not differ between tasks. Finally, analyses of both memory accuracy and trial-by-trial ratings of perceived combination success suggested that older adults had disproportionate difficulty applying the conceptual combination strategy to word pairs that began with abstract nouns. Overall, these results indicate that changes to integrative language processing that occur with age are not independent of – and may sometimes exacerbate – age-related memory decline.

Downstream Behavioral and Electrophysiological Consequences of Word Prediction on Recognition Memory

When people process language, they can use context to predict upcoming information, influencing processing and comprehension as seen in both behavioral and neural measures. Although numerous studies have shown immediate facilitative effects of confirmed predictions, the downstream consequences of prediction have been less explored. In the current study, we examined those consequences by probing participants' recognition memory for words after they read sets of sentences. Participants read strongly and weakly constraining sentences with expected or unexpected endings ("I added my name to the list/basket"), and later were tested on their memory for the sentence endings while EEG was recorded. Critically, the memory test contained words that were predictable ("list") but were never read (participants saw "basket"). Behaviorally, participants showed successful discrimination between old and new items, but false alarmed to the expected-item lures more often than to new items, showing that predicted words or concepts can linger, even when predictions are disconfirmed. Although false alarm rates did not differ by constraint, event-related potentials (ERPs) differed between false alarms to strongly and weakly predictable words. Additionally, previously unexpected (compared to previously expected) endings that appeared on the memory test elicited larger N1 and LPC amplitudes, suggesting greater attention and episodic recollection. In contrast, highly predictable sentence endings that had been read elicited reduced LPC amplitudes during the memory test. Thus, prediction can facilitate processing in the moment, but can also lead to false memory and reduced recollection for predictable information.

Event-related brain potentials reveal how multiple aspects of semantic processing unfold across parafoveal and foveal vision during sentence reading

Recent event-related brain potential (ERP) experiments have demonstrated parafoveal N400 expectancy and congruity effects, showing that semantic information can be accessed from words in parafoveal vision (a conclusion also supported by some eye-tracking work). At the same time, it is unclear how higher-order integrative aspects of language comprehension unfold across the visual field during reading. In the current study, we recorded ERPs in a parafoveal flanker paradigm, while readers were instructed to read passively for comprehension or to judge the plausibility of sentences in which target words varied in their semantic expectancy and congruity. We directly replicated prior work showing graded N400 effects for parafoveal viewing, which are then not duplicated when the target words are processed foveally. Critically, although N400 effects were not modulated by task goals, a posteriorly distributed late positive component thought to reflect semantic integration processes was observed to semantic incongruities only in the plausibility judgment task. However, this effect was observed at a considerable delay, appearing only after words had moved into foveal vision. Our findings thus suggest that semantic access can be initiated in parafoveal vision, whereas central foveal vision may be necessary to enact higher-order (and task-dependent) integrative processing.

Talker-specific predictions during language processing

Language comprehension is shaped by world knowledge. After hearing about "a farm animal," meanings of typical ("cow") versus atypical exemplars ("ox") are more accessible, as evidenced by N400 responses. Moreover, atypical exemplars elicit a larger post-N400 frontal positivity than typical and incongruous ("ivy") exemplars, indexing the integration of unexpected information. Do listeners adapt this category knowledge to specific talkers? We first replicated typicality effects in the auditory modality. Then, we extended the design to a two-talker context: talkers alternated cueing (Bob: "Susan, name a farm animal") and answering (Susan: "cow"). Critically, participants first heard interviews in which one talker revealed strong associations with atypical exemplars (Susan works on an ox farm). We observed increased frontal positivity to a typical exemplar ("cow") said by Susan compared to Bob, indicating participants appreciated that the typical exemplar was atypical for Susan. These results suggest that comprehenders can tailor their expectations to the talker.

The P3b and P600(s): Positive contributions to language comprehension

Since its discovery in the 1960s, the P300 has been contributing both directly and indirectly to language research. Perhaps most notably, it has been suggested that the P600, an ERP component that was first characterized in the context of syntactic processing, could be a variant of the P3b subcomponent of the P300. Here, we review studies on both sides of the debate. We also review the "semantic P600," a positivity with a similar time course and distribution to the P600 seen for syntactic manipulations but that is obtained in response to some types of semantic anomalies. Because most current theories of the P600 try to account for both the syntactic and the semantic variant, linking the syntactic P600 to the P3b might also imply a similar link for the semantic P600. However, we describe emerging research in our lab that casts doubt on the idea that the syntactic P600 and the semantic P600 are the same effect. We argue that grouping ERP responses primarily by domain (language vs. nonlanguage) is likely to be misleading and suggest alternative ways of determining whether ERP effects reflect similar or different processing mechanisms.

Lingering expectations: A pseudo-repetition effect for words previously expected but not presented

Prediction can help support rapid language processing. However, it is unclear whether prediction has downstream consequences, beyond processing in the moment. In particular, when a prediction is disconfirmed, does it linger, or is it suppressed? This study manipulated whether words were actually seen or were only expected, and probed their fate in memory by presenting the words (again) a few sentences later. If disconfirmed predictions linger, subsequent processing of the previously expected (but never presented) word should be similar to actual word repetition. At initial presentation, electrophysiological signatures of prediction disconfirmation demonstrated that participants had formed expectations. Further downstream, relative to unseen words, repeated words elicited a strong N400 decrease, an enhanced late positive complex (LPC), and late alpha band power decreases. Critically, like repeated words, words previously expected but not presented also attenuated the N400. This "pseudo-repetition effect" suggests that disconfirmed predictions can linger at some stages of processing, and demonstrates that prediction has downstream consequences beyond rapid on-line processing.

What does "it" mean, anyway? Examining the time course of semantic activation in reference resolution

Pronouns serve a critical referential function, yet the cognitive processes engaged during pronoun comprehension remain incompletely understood. One view is that encountering a pronoun leads the comprehender to reactivate the semantic features of its antecedent. We examined this by manipulating the concreteness of a noun antecedent and assessing whether an Event Related Potential (ERP) concreteness effect was elicited at a downstream pronoun. We observed a robust concreteness effect at the noun, but no similar effect at the pronoun. We also examined whether N400 semantic priming from the antecedent would increase on content words shortly following the pronoun, relative to those preceding it. Again, although we observed semantic priming following the noun, it did not increase following the pronoun. Our data suggest that pronouns do not induce the activation of (much) new semantic information in long-term memory, perhaps instead triggering an attentional shift towards their antecedents' extant representations within working memory.

Your favorite number is special (to you): Evidence for item-level differences in retrieval of information from numerals

Arabic numerals have come to be used for many purposes beyond representing a particular quantity (e.g., as a label for an athlete on their jersey), but it remains to be determined how this type of meaningfulness is accessed and utilized by readers. Motivated by previous work showing that item-level ratings of personal familiarity can influence traditional indices of memory retrieval, we recorded ERPs while participants read double-digit Arabic numerals (e.g., "65"), presented in a list, and rated whether or not each was familiar/personally meaningful. All numbers repeated after a few intervening trials. The effect of number repetition on the N400 was not impacted by subjective judgments of familiarity, suggesting that all numbers (personally meaningful or not) make initial contact with semantics, facilitating semantic access on second exposure. However, consistent with findings from prior studies of memory for letter strings and visual patterns, there was a late positivity (LPC) on second presentation, selective to numbers rated as familiar. This is the first electrophysiological evidence that readers can use Arabic numerals to guide explicit retrieval of non-numerical information.

Contextual constraints on lexico-semantic processing in aging: Evidence from single-word event-related brain potentials

The current study reports the effects of accumulating contextual constraints on neural indices of lexico-semantic processing (i.e., effects of word frequency and orthographic neighborhood) as a function of normal aging. Event-related brain potentials were measured from a sample of older adults as they read sentences that were semantically congruent, provided only syntactic constraints (syntactic prose), or were random word strings. A linear mixed-effects modeling approach was used to probe the effects of accumulating contextual constraints on N400 responses to individual words. Like young adults in prior work, older adults exhibited a classic word position context effect on the N400 in congruent sentences, although the magnitude of the effect was reduced in older relative to younger adults. Moreover, by modeling single-word variability in N400 responses, we observed robust effects of orthographic neighborhood density that were larger in older adults than the young, and preserved effects word frequency. Importantly, in older adults, frequency effects were not modulated by accumulating contextual constraints, unlike in the young. Collectively, these findings indicate that older adults are less likely (or able) to use accumulating top-down contextual constraints, and therefore rely more strongly on bottom-up lexical features to guide semantic access of individual words during sentence comprehension.

Sensory and semantic activations evoked by action attributes of manipulable objects: Evidence from ERPs

"Two route" theories of object-related action processing posit different temporal activation profiles of grasp-to-move actions (rapidly evoked based on object structure) versus skilled use actions (more slowly activated based on semantic knowledge). We capitalized on the exquisite temporal resolution and multidimensionality of Event-Related Potentials (ERPs) to directly test this hypothesis. Participants viewed manipulable objects (e.g., calculator) preceded by objects sharing either "grasp", "use", or no action attributes (e.g., bar of soap, keyboard, earring, respectively), as well as by action-unrelated but taxonomically-related objects (e.g., abacus); participants judged whether the two objects were related. The results showed more positive responses to "grasp-to-move" primed objects than "skilled use" primed objects or unprimed objects starting in the P1 (0-150 ms) time window and continuing onto the subsequent N1 and P2 components (150-300 ms), suggesting that only "grasp-to-move", but not "skilled use", actions may facilitate visual attention to object attributes. Furthermore, reliably reduced N400s (300-500 ms), an index of semantic processing, were observed to taxonomically primed and "skilled use" primed objects relative to unprimed objects, suggesting that "skilled use" action attributes are a component of distributed, multimodal semantic representations of objects. Together, our findings provide evidence supporting two-route theories by demonstrating that "grasp-to-move" and "skilled use" actions impact different aspects of object processing and highlight the relationship of "skilled use" information to other aspects of semantic memory.

Event-related brain potentials reveal age-related changes in parafoveal-foveal integration during sentence processing

Normative aging is associated with deficits in visual acuity and cognitive control that impact the allocation of visual attention, but little is known about how those changes affect information extraction and integration during visual language comprehension in older adulthood. In the current study, we used a visual hemi-field flanker RSVP paradigm with event-related brain potentials to study how older readers process fine-grained aspects of semantic expectancy in parafoveal and foveal vision. Stimuli consisted of high constraint sentences with expected, unexpected but plausible, or anomalous parafoveal target words, as well as low constraint sentences with neutral but expected target words. Older adults showed graded parafoveal N400 effects that were strikingly similar to younger readers, indicating intact parafoveal semantic processing. However, whereas young adults were able to use this parafoveal pre-processing to facilitate subsequent foveal viewing, resulting in a reduced foveal N400 effect, older adults were not able to. Instead, older adults re-processed the semantics of words in foveal vision, resulting in a larger foveal N400 effect relative to the young. Collectively, our findings suggest that although parafoveal semantic processing per se is preserved in aging, there exists an age-related deficit in the ability to rapidly integrate parafoveal and foveal visual semantic representations.

Age-related shifts in hemispheric dominance for syntactic processing

Recent ERP data from young adults have revealed that simple syntactic anomalies elicit different patterns of lateralization in right-handed participants depending upon their familial sinistrality profile (whether or not they have left-handed biological relatives). Right-handed participants who do not have left-handed relatives showed a strongly lateralized response pattern, with P600 responses following left-hemisphere-biased presentations and N400 responses following right-hemisphere-biased presentations. Given that the literature on aging has documented a tendency to change across adulthood from asymmetry of function to a more bilateral pattern, we tested the stability of this asymmetric response to syntactic violations by recording ERPs as 24 older adults (age 60+) with no history of familial sinistrality made grammaticality judgments on simple two-word phrases. Results showed that the asymmetric pattern observed in right-handed adults without familial sinistrality indeed changes with age, such that P600 responses come to be elicited not only with left-hemisphere-biased but also with right-hemisphere-biased presentations in older adults. These findings suggest that, as with many other cognitive functions, syntactic processing becomes more bilateral with age.

The language of arithmetic across the hemispheres: An event-related potential investigation

Arithmetic expressions, like verbal sentences, incrementally lead readers to anticipate potential appropriate completions. Existing work in the language domain has helped us understand how the two hemispheres differently participate in and contribute to the cognitive process of sentence reading, but comparatively little work has been done with mathematical equation processing. In this study, we address this gap by examining the ERP response to provided answers to simple multiplication problems, which varied both in levels of correctness (given an equation context) and in visual field of presentation (joint attention in central presentation, or biased processing to the left or right hemisphere through contralateral visual field presentation). When answers were presented to any of the visual fields (hemispheres), there was an effect of correctness prior to the traditional N400 timewindow, which we interpret as a P300 in response to a detected target item (the correct answer). In addition to this response, equation answers also elicited a late positive complex (LPC) for incorrect answers. Notably, this LPC effect was most prominent in the left visual field (right hemisphere), and it was also sensitive to the confusability of the wrong answer - incorrect answers that were closely related to the correct answer elicited a smaller LPC. This suggests a special, prolonged role for the right hemisphere during answer evaluation.

Flexible conceptual combination: Electrophysiological correlates and consequences for associative memory

When meaningful stimuli such as words are encountered in groups or pairs (e.g., "elephant-ferry"), they can be processed either separately or as an integrated concept ("an elephant ferry"). Prior research suggests that memory for integrated associations is supported by different mechanisms than is memory for nonintegrated associations. However, little is known about the neurocognitive mechanisms that support the integration of novel stimulus pairs. We recorded ERPs while participants memorized sequentially presented, unrelated noun pairs using a strategy that either did or did not involve attempting to construct coherent definitions. We varied the concreteness of the first noun in each pair to examine whether conceptual combination instructions would induce compositional concreteness effects, or differences in ERPs evoked by the second noun as a function of the concreteness of the first noun. We found that the conceptual combination task, but not the noncombinatory encoding task, produced compositional concreteness effects on a late frontal negativity previously linked to visual imagery. Moreover, word pairs studied under conceptual combination instructions showed evidence of more unitized or holistic memory representations on associative recognition and free recall tests. Finally, item analyses indicated that (a) items with higher normed imageability ratings were rated by participants as easier to conceptually combine, and (b) in the conceptual combination task, ease-of-combination ratings mediated an indirect relationship between imageability and subsequent associative memory. These data are suggestive of a role of compositional imagery in the online formation of novel concepts via conceptual combination.

Pace Yourself: Intraindividual Variability in Context Use Revealed by Self-paced Event-related Brain Potentials

Event-related brain potentials (ERPs) have revealed multiple mechanisms by which contextual constraints impact language processing. At the same time, little work has examined the trial-to-trial dynamics of context use in the brain. In the current study, we probed intraindividual variability in behavioral and neural indices of context processing during reading. In a concurrent self-paced reading and ERP paradigm, participants read sentences that were either strongly or weakly constraining completed with an expected or unexpected target word. Our findings revealed substantial within-subject variability in behavioral and neural responses to contextual constraints. First, context-based amplitude reductions of the N400, a component linked to semantic memory access, were largest among trials eliciting the slowest RTs. Second, the RT distribution of unexpected words in strongly constraining contexts was positively skewed, reflecting an increased proportion of very slow RTs to trials that violated semantic predictions. Among those prediction-violating trials eliciting faster RTs, a late sustained anterior positivity was observed. However, among trials producing the differentially slowed RTs to prediction violations, we observed a markedly earlier effect of constraint in the form of an anterior N2, a component linked to conflict resolution and the cognitive control of behavior. The current study provides the first neurophysiological evidence for the direct role of cognitive control functions in the volitional control of reading. Collectively, our findings suggest that context use varies substantially within individual participants and that coregistering behavioral and neural indices of online sentence processing offers a window into these single-item dynamics.

Do Morphemes Matter when Reading Compound Words with Transposed Letters? Evidence from Eye-Tracking and Event-Related Potentials

The current study investigates the online processing consequences of encountering compound words with transposed letters (TLs), to determine if TLs that cross morpheme boundaries are more disruptive to reading than those within a single morpheme, as would be predicted by accounts of obligatory morpho-orthopgrahic decomposition. Two measures of online processing, eye movements and event-related potentials (ERPs), were collected in separate experiments. Participants read sentences containing correctly spelled compound words (cupcake), or compounds with TLs occurring either across morpheme boundaries (cucpake) or within one morpheme (cupacke). Results showed that between- and within-morpheme transpositions produced equal processing costs in both measures, in the form of longer reading times (Experiment 1) and a late posterior positivity (Experiment 2) that did not differ between conditions. Findings converge to suggest that within- and between-morpheme TLs are equally disruptive to recognition, providing evidence against obligatory morpho-orthographic processing and in favor of whole-word access of English compound words during sentence reading.

Out of the corner of my eye: Foveal semantic load modulates parafoveal processing in reading

In 2 experiments, we examined the impact of foveal semantic expectancy and congruity on parafoveal word processing during reading. Experiment 1 utilized an eye-tracking gaze-contingent display change paradigm, and Experiment 2 measured event-related brain potentials (ERPs) in a modified flanker rapid serial visual presentation (RSVP) paradigm. Eye-tracking and ERP data converged to reveal graded effects of foveal load on parafoveal processing. In Experiment 1, when word n was highly expected, and thus foveal load was low, there was a large parafoveal preview benefit to word n + 1. When word n was unexpected but still plausible, preview benefits to n + 1 were reduced in magnitude, and when word n was semantically incongruent, the preview benefit to n + 1 was unreliable in early pass measures. In Experiment 2, ERPs indicated that when word n was expected, and thus foveal load was low, readers successfully discriminated between valid and orthographically invalid previews during parafoveal perception. However, when word n was unexpected, parafoveal processing of n + 1 was reduced, and it was eliminated when word n was semantically incongruent. Taken together, these findings suggest that sentential context modulates the allocation of attention in the parafovea, such that covert allocation of attention to parafoveal processing is disrupted when foveal words are inconsistent with expectations based on various contextual constraints. (PsycINFO Database Record

Alpha and theta band dynamics related to sentential constraint and word expectancy

Despite strong evidence for prediction during language comprehension, the underlying mechanisms, and the extent to which they are specific to language, remain unclear. Re-analyzing an ERP study, we examined responses in the time-frequency domain to expected and unexpected (but plausible) words in strongly and weakly constraining sentences, and found results similar to those reported in nonverbal domains. Relative to expected words, unexpected words elicited an increase in the theta band (4-7 Hz) in strongly constraining contexts, suggesting the involvement of control processes to deal with the consequences of having a prediction disconfirmed. Prior to critical word onset, strongly constraining sentences exhibited a decrease in the alpha band (8-12 Hz) relative to weakly constraining sentences, suggesting that comprehenders can take advantage of predictive sentence contexts to prepare for the input. The results suggest that the brain recruits domain-general preparation and control mechanisms when making and assessing predictions during sentence comprehension.

The N400 reveals how personal semantics is processed: Insights into the nature and organization of self-knowledge

There is growing recognition that some important forms of long-term memory are difficult to classify into one of the well-studied memory subtypes. One example is personal semantics. Like the episodes that are stored as part of one's autobiography, personal semantics is linked to an individual, yet, like general semantic memory, it is detached from a specific encoding context. Access to general semantics elicits an electrophysiological response known as the N400, which has been characterized across three decades of research; surprisingly, this response has not been fully examined in the context of personal semantics. In this study, we assessed responses to congruent and incongruent statements about people's own, personal preferences. We found that access to personal preferences elicited N400 responses, with congruency effects that were similar in latency and distribution to those for general semantic statements elicited from the same participants. These results suggest that the processing of personal and general semantics share important functional and neurobiological features.

Revisiting the incremental effects of context on word processing: Evidence from single-word event-related brain potentials

The amplitude of the N400-an event-related potential (ERP) component linked to meaning processing and initial access to semantic memory-is inversely related to the incremental buildup of semantic context over the course of a sentence. We revisited the nature and scope of this incremental context effect, adopting a word-level linear mixed-effects modeling approach, with the goal of probing the continuous and incremental effects of semantic and syntactic context on multiple aspects of lexical processing during sentence comprehension (i.e., effects of word frequency and orthographic neighborhood). First, we replicated the classic word-position effect at the single-word level: Open-class words showed reductions in N400 amplitude with increasing word position in semantically congruent sentences only. Importantly, we found that accruing sentence context had separable influences on the effects of frequency and neighborhood on the N400. Word frequency effects were reduced with accumulating semantic context. However, orthographic neighborhood was unaffected by accumulating context, showing robust effects on the N400 across all words, even within congruent sentences. Additionally, we found that N400 amplitudes to closed-class words were reduced with incrementally constraining syntactic context in sentences that provided only syntactic constraints. Taken together, our findings indicate that modeling word-level variability in ERPs reveals mechanisms by which different sources of information simultaneously contribute to the unfolding neural dynamics of comprehension.