N400 Attenuation Research Articles

Schema-congruency supports the formation of unitized representations: Evidence from event-related potentials

The main goal of the present study was to investigate whether schema-based encoding of novel word pairs (i.e., novel compound words) supports the formation of unitized representations and thus, associative familiarity-based recognition. We report two experiments that both comprise an incidental learning task, in which novel noun-noun compound words were presented in semantically congruent contexts, enabling schema-supported processing of both constituents, contrasted with a schema-neutral condition. In Experiment 1, the effects of schema congruency on memory performance were larger for associative memory performance than for item memory performance in a memory test in which intact, recombined, and new compound words had to be discriminated. This supports the view that schema congruency boosts associative memory by promoting unitization. When contrasting event-related potentials (ERPs) for hits with correct rejections or associative misses, an N400 attenuation effect (520–676 ms) indicating absolute familiarity was present in the congruent condition, but not in the neutral condition. In line with this, a direct comparison of ERPs on hits across conditions revealed more positive waveforms in the congruent than in the neutral condition. This suggests that absolute familiarity contributes to associative recognition memory when schema-supported processing is established. In Experiment 2, we tested whether schema congruency enables the formation of semantically overlapping representations. Therefore, we included semantically similar lure compound words in the test phase and compared false alarm rates to these lures across conditions. In line with our hypothesis, we found higher false alarm rates in the congruent as compared to the neutral condition. In conclusion, we provide converging evidence for the view that schema congruency enables the formation of unitized representations and supports familiarity-based memory retrieval.

Evidence of rapid automatic translation in Korean-English bilinguals using masked implicit priming: An ERP study

The present study used a masked implicit priming paradigm to test if L1 to L2 translation occurs automatically and rapidly. Korean-English bilinguals performed a lexical decision task when English L2 targets (e.g., FACE) were translation equivalent to the L1 prime (얼굴 elkwul meaning ‘face’) or had phonological overlap with its translation to varying degrees: moderate (FAKE), minimal (FOOL), or unrelated. The translation equivalent targets resulted in N250 and N400 attenuation, reflecting facilitation in sublexical and lexical mapping of the target words, respectively. Crucially, target words which were phonologically related to the implicitly activated translation equivalent (face–FAKE/FOOL) also demonstrated N250/N400 modulation in the absence of semantic overlap. Additionally, the pattern of effects obtained against the unrelated condition differed between the implicitly related primes, with greater phonological overlap resulting in increased negativity, while minimal overlap led to attenuation. These findings suggest translation via direct lexical association occurring automatically at earlier stages of visual word recognition prior to lexical selection in bilinguals.

Task context dissociates the FN400 and the N400.

In event-related potential studies, familiarity-based recognition has been associated with the FN400, that is, more positive-going waveforms for old items than new items 300-500 ms post-stimulus onset, maximal at frontal electrodes. We tested the proposition that the FN400 reflects the attribution of unexpected processing fluency to familiarity. This implies that the FN400 is greater when fluency is less expected, that is, for less familiar stimuli. Moreover, the FN400 should be modulated by the goal of remembering and only elicited when fluency is correctly attributed to the past, that is, by correct old responses in recognition memory tests. In the absence of a retrieval task, enhanced fluency for repeated items should be associated with an N400 attenuation as no episodic attribution takes place. In an incidental study-test design with words of low and high life-time familiarity, participants made pleasantness judgments for half of the studied words. The other half re-appeared in a recognition test. Only in the latter task, participants had the goal of remembering. As both tasks included also new words, we could compare old/new effects under conditions in which both effects are driven by increased fluency for repeated words. We did not find the expected differences in the FN400 for low vs. high life-time familiarity items. However, as expected, we found a frontally distributed FN400 in the recognition test whereas the old/new effect in the pleasantness task resembled an N400 effect. This supports the view that the FN400 occurs when fluency is attributed to familiarity during a recognition decision.

The dynamics of spoken word recognition in bilinguals

AbstractThis study examined whether bilinguals automatically activate lexical options from both of their languages when performing a picture matching task in their dominant language (L1) by using event related potentials. English–French bilinguals and English monolinguals performed a picture-spoken word matching task with three conditions: match (BEACH-“beach”), unrelated mismatch (BEACH-“tack”), and L2 onset competitor mismatch (BEACH-“plaid”; plaid sounds like plage, the French word for beach). Critically, bilinguals, but not monolinguals, showed reduced N400s for L2-cohort vs. unrelated mismatches. The results provide clear evidence that when bilinguals identify pictures, they automatically activate lexical options from both languages, even when expecting oral input from only their dominant language. N400 attenuation suggests bilinguals activate but do not expect L2 lexical options.

Phonologically-mediated meaning activation in monolinguals and bilinguals

Abstract The current study investigated how language experience impacts phonologically-mediated meaning activation. Monolinguals and bilinguals made living/non-living judgments on English homophones (e.g., beech, beach) while Event-Related Potentials (ERPs) were recorded. Context was manipulated by making the preceding trial either unrelated (e.g., servant → beech) or semantically-related, creating priming. The related context either strengthened (e.g., oak → beech) or diminished (e.g., oak → beach) a homophone’s meaning. In the unrelated context, both groups utilized phonology similarly to access meaning, as evidenced by a later N400 and a larger late positive component (LPC) for homophones than for non-homophonic words. However, when the context primed the incorrect meaning (e.g., oak → beach), only monolinguals exhibited N400 attenuation and delayed LPCs, indicating that they were mistakenly using phonology and context to access meaning and were then required to reanalyze their interpretation. These results provide insight into how oral language experience impacts phonological activation of meaning.

Substantial gains in word learning ability between 20 and 24 months: A longitudinal ERP study

This longitudinal ERP study investigated changes in children’s ability to map novel words to novel objects during the dynamic period of vocabulary growth between 20 and 24months. During this four-month period the children on average tripled their productive vocabulary, an increase which was coupled with changes in the N400 effect to pseudoword-referent associations. Moreover, productive vocabulary size was related to the dynamics of semantic processing during novel word learning. In children with large productive vocabularies, the N400 amplitude was linearly reduced during the five experimental learning trials, consistent with the repetition effect typically seen in adults, while in children with smaller vocabularies the N400 attenuation did not appear until the end of the learning phase. Vocabulary size was related only to modulation of the N400 to pseudowords, not to real words. These findings demonstrate a remarkable development of fast mapping ability between 20 and 24months.

Conceptual fluency increases recollection: behavioral and electrophysiological evidence.

It is widely established that fluency can contribute to recognition memory. Previous studies have found that enhanced fluency increases familiarity, but not recollection. The present study was motivated by a previous finding that conceptual priming affected recollection. We used event-related potentials to investigate the electrophysiological correlates of these effects with conceptually related two-character Chinese words. We found that previous conceptual priming effects on conceptual fluency only increased the incidence of recollection responses. We also found that enhanced conceptual fluency was associated with N400 attenuation, which was also correlated with the behavioral indicator of recollection. These results suggest that the N400 effect might be related to the impact of conceptual fluency on recollection recognition. These study findings provide further evidence for the relationship between fluency and recollection.

Reversing expectations during discourse comprehension

In two event-related potential experiments, we asked whether comprehenders used the concessive connective, even so, to predict upcoming events. Participants read coherent and incoherent scenarios, with and without even so, e.g. ‘Elizabeth had a history exam on Monday. She took the test and aced/failed it. (Even so), she went home and celebrated wildly’, as they rated coherence (Experiment 1) or simply answered intermittent comprehension questions (Experiment 2). The semantic function of even so was used to reverse real-world knowledge predictions, leading to an attenuated N400 to coherent versus incoherent target words (‘celebrated’). Moreover, its pragmatic communicative function enhanced predictive processing, leading to more N400 attenuation to coherent targets in scenarios with than without even so. This benefit however, did not come for free: the detection of failed event predictions triggered a later posterior positivity and/or an anterior negativity effect, and costs of maintaining alternative likelihood relations manifest as a sustained negativity effect on sentence-final words.

A funny thing happened on the way to articulation: N400 attenuation despite behavioral interference in picture naming

We measured Event-Related Potentials (ERPs) and naming times to picture targets preceded by masked words (stimulus onset asynchrony: 80ms) that shared one of three different types of relationship with the names of the pictures: (1) Identity related, in which the prime was the name of the picture (“socks” – <picture of socks>), (2) Phonemic Onset related, in which the initial segment of the prime was the same as the name of the picture (“log” – <picture of a leaf>), and (3) Semantically related in which the prime was a co-category exemplar and associated with the name of the picture (“cake” – <picture of a pie>). Each type of related picture target was contrasted with an Unrelated picture target, resulting in a 3×2 design that crossed Relationship Type between the word and the target picture (Identity, Phonemic Onset and Semantic) with Relatedness (Related and Unrelated). Modulation of the N400 component to related (versus unrelated) pictures was taken to reflect semantic processing at the interface between the picture’s conceptual features and its lemma, while naming times reflected the end product of all stages of processing. Both attenuation of the N400 and shorter naming times were observed to pictures preceded by Identity related (versus Unrelated) words. No ERP effects within 600ms, but shorter naming times, were observed to pictures preceded by Phonemic Onset related (versus Unrelated) words. An attenuated N400 (electrophysiological semantic priming) but longer naming times (behavioral semantic interference) were observed to pictures preceded by Semantically related (versus Unrelated) words. These dissociations between ERP modulation and naming times suggest that (a) phonemic onset priming occurred late, during encoding of the articulatory response, and (b) semantic behavioral interference was not driven by competition at the lemma level of representation, but rather occurred at a later stage of production.

Bilateral activation of semantic information on left-handers

To investigate interhemispheric transfer of language information in left-handed participants, event-related potentials were recorded during a semantic matching task. The stimuli were prime and target word pairs sequentially presented to either the left (LVF) or the right (RVF) visual field. A posterior slow negative shift (SNp) preceding target presentation was measured as an index of storage of language information and an N400 attenuation elicited for targets was used to analyze the priming effect. The SNp developed over both hemispheres for RVF primes, whereas for LVF primes it declined over the left hemisphere. The N400 attenuation was larger in the right hemisphere than in the left hemisphere. The lateralized pattern of the SNp development and the N400 attenuation, which contrasts with the previous finding in right handers (Kato & Okita, 2008), suggests that the transfer of language information from the dominant hemisphere to the nondominant hemisphere is reduced.

Reduced resource optimization in male alcoholics: N400 in a lexical decision paradigm.

Event Related Potential (ERP) studies have highlighted some measures, notably P3 amplitude, that are associated with both state and trait deficits in alcoholism, while studies examining N400 amplitude in alcoholism are few. The present study aims to examine differences in the N400 component, an electrophysiological correlate of semantic priming, in event-related potentials from a lexical decision task in 87 alcohol dependent subjects and 57 community controls. Each subject was presented with 300 stimuli sequentially in a quasi-randomized design, where 150 stimuli were words and 150 were non-words. The subjects made a lexical decision indicating the word/non-word status with a button press. Among the words, 50 words (primed) were always preceded by their antonyms (prime, n=50), whereas the remaining 50 words were unrelated. N400 amplitude and latency measures were compiled from ERPs to the primed and unprimed words. Corresponding reaction time (RT) and response characteristics were also analyzed. Control subjects revealed a significant attenuation of the N400 response to the primed word when compared to the unprimed word. Significantly less attenuation was observed in alcohol dependent subjects. No significant group differences were seen for latency and behavioral measures. All subjects had slower RT for unprimed words compared to primed words; however significantly less RT savings between the unprimed and primed condition was noted for alcoholics. These results suggest a reduced flexibility in the cognitive networks and a lack of resource optimization in alcoholics. The reduced attenuation of N400 during the primed condition in the alcohol dependent subjects may reflect an inability to engage similar neuronal substrates associated with semantic relatedness as seen in the controls. As diminished N400 attenuation during priming is observed in both alcoholics and high risk subjects, it may be a marker of risk and a good endophenotype for alcoholism.

Not all disfluencies are are equal: The effects of disfluent repetitions on language comprehension

Disfluencies can affect language comprehension, but to date, most studies have focused on disfluent pauses such as er. We investigated whether disfluent repetitions in speech have discernible effects on listeners during language comprehension, and whether repetitions affect the linguistic processing of subsequent words in speech in ways which have been previously observed with ers. We used event-related potentials (ERPs) to measure participants’ neural responses to disfluent repetitions of words relative to acoustically identical words in fluent contexts, as well as to unpredictable and predictable words that occurred immediately post-disfluency and in fluent utterances. We additionally measured participants’ recognition memories for the predictable and unpredictable words. Repetitions elicited an early onsetting relative positivity (100–400ms post-stimulus), clearly demonstrating listeners’ sensitivity to the presence of disfluent repetitions. Unpredictable words elicited an N400 effect. Importantly, there was no evidence that this effect, thought to reflect the difficulty of semantically integrating unpredictable compared to predictable words, differed quantitatively between fluent and disfluent utterances. Furthermore there was no evidence that the memorability of words was affected by the presence of a preceding repetition. These findings contrast with previous research which demonstrated an N400 attenuation of, and an increase in memorability for, words that were preceded by an er. However, in a later (600–900ms) time window, unpredictable words following a repetition elicited a relative positivity. Reanalysis of previous data confirmed the presence of a similar effect following an er. The effect may reflect difficulties in resuming linguistic processing following any disruption to speech.

他者視線が観察者の性ステレオタイプ活性に及ぼす影響―事象関連電位を用いた検討―

To examine the effects of observed gaze on gender priming, event-related potentials (ERPs) were recorded during performance of a gender matching task, in which face (prime) and word (target) pairs were sequentially presented. Twelve right-handed participants were required to make a judgment whether or not a gender of gazed or averted face is compatible with gender stereotype of a target word. An early negative component prior to the target was invariant between a gazed face and an averted face conditions. In the gazed face condition, an N400 attenuation was observed for a target word related to a face in terms of a gender stereotype. On the contrary, such a gender priming effect did not appear in the averted face condition. These findings suggest that semantic knowledge of gender stereotype is activated when the observed face gazes at the viewer.

視野内視野間意味プライミング―事象関連脳電位を用いた研究―

To investigate interhemispheric transfer of language information, event-related brain potentials (ERPs) were recorded during performance of a semantic matching task in which prime and target word pairs were sequentially presented to either the left (LVF) or the right (RVF) visual field. A posterior slow negative shift prior to the target presentation developed over both hemispheres for LVF primes, whereas for RVF primes the negative shift declined over the right hemisphere. An N400 attenuation was observed for targets semantically related to the primes and was predominant over the left parietal site. The N400 priming effect was significantly reduced for LVF targets preceded by RVF primes, compared to other patterns of presentation. These findings indicate that semantic priming is attenuated in the right hemisphere when information is transferred from the left hemisphere.

Interaural attention switching suppresses N400 attenuation with spoken word repetition

Event-related brain potentials were recorded from participants who listened to two pairs of words (and occasionally nonwords) simultaneously presented to both ears with stimulus onset asynchrony (SOA) of 1 s on a trial. When participants were instructed to fixate their attention to one ear and detect nonwords, the N400 attenuation was observed for a word repeated in the attended ear. The requirement of interaural attention switching between the first and second presentations of word pairs, however, suppressed the repetition effect on N400, even when the first and repeated presentations of a word were attended. The suppression of N400 attenuation was interpreted to indicate that attention switching interferes with the immediate availability of the decision for the first presentation in working memory.

特定の語彙に対する注意の焦点化が意味的関連性によるN400減衰に及ぼす影響

特定の語彙に対する注意の焦点化が意味的関連性によるN400減衰に及ぼす影響

Semantic processing of words in selective listening: an examination using recognition tests and event-related brain potentials

Two experiments were conducted to investigate the degree of semantic processing for unattended words. In a dichotic listening task, each participant was required to attend selectively to either a word sequence in one ear or a speech passage in the opposite ear. The selective listening was confirmed by attenuated P1-N1 and N400 waves of the event-related brain potential to unattended words. The N400 attenuation with semantic priming was observed only for attended words. In a following recognition test with a booklet and auditory presentation, the percentage of false alarms for "new" words (or lures) semantically related to "old" words was higher when the "old" words were attended in selective listening than when unattended. These findings suggest that selective attention can act before and/or at a level of semantic processing.

Selective attention and N400 attenuation with spoken word repetition

In two experiments, event-related brain potential were recorded to word pairs simultaneously presented to both ears, with instructions to attend to one ear and detect occasional nonwords in that ear. This attentional manipulation yielded four patterns of word repetition on successive trials: first and second presentations attended (AA), both unattended (UU), and across ears (AU and UA). A prominent attenuation of N400 due to immediate repetition of words was observed on AA trials. However, when first presentations were ignored on UU and UA trials, no repetition effect was obtained. These findings indicate that the repetition effect on N400 depends on attentional processing of first presentations.

Memory function in aging and Parkinson's disease--an event-related potential study

The N400 of event-related potentials (ERPs) was recorded in 17 healthy young subjects (mean age 24.4 years), 14 healthy old subjects (healthy control subjects, mean age 62.7 years), and 21 patients with nondemented Parkinson's disease (PD, mean age, 63.8 years) as they listened to words or nonwords. Some words were repeated immediately after the initial presentation (2 sec), while others were repeated after 5 intervening words (12 sec) or after 2 to 4 minutes. The subjects were required to respond to occasional nonwords. Rey's auditory verbal learning test(AVLT) was also performed. The mean N400 amplitude was smaller in patients with PD than in either healthy group, but there was no difference between the two healthy groups. In the young subjects, N400 was attenuated for repeated words, and the attenuation was more pronounced for immediate than for delayed repetitions. N400 attenuation in the old subjects was more markedly reduced as the interval between the 1st and 2nd presentation increased than in the young subjects. In PD patients, attenuation was noted only for immediate repetition. Free recall by the old subjects was impaired relative to the young subjects throughout the AVLT trials, and was even more impaired in patients with PD. In addition, the number of free recalls increased less with the number of trials in patients with PD than in the old subjects. These results may indicate that episodic memory declines with advancing age, and declines even more in patients with PD. In addition, the ability to transform information form short-term memory to long-term memory appear to be impaired in patients with PD.