Bilingual problem size effect: an ERP study of multiplication verification and production in two languages.

The problem size effect (PSE) is defined by better performance solving small problems (e.g., 2x4) than large problems (e.g., 8x9). For monolinguals, the PSE is larger when problems are presented in unfamiliar formats (e.g., written words), reflecting increased processing difficulty. Bilinguals are typically faster and more accurate at retrieving multiplication facts in the language of learning (LA+) than in their other language (LA-). We hypothesized that the less familiar arithmetic language (i.e., LA-) would elicit larger PSEs than LA+. Here, fluent Spanish-English bilingual adults verified spoken multiplication problems presented in LA+ and LA- while event-related potentials (ERPs) were recorded (Experiment 1A). To further promote language differences, we increased task difficulty by presenting problems at a faster pace (Experiment 1B) and requiring bilinguals to verbally produce solutions (Experiment 2). Language differences in performance were only observed for Experiment 2, where solutions were produced more slowly in LA- than LA+. In the ERPs, a PSE was driven by larger P300s for small than large solutions. A language effect was only observed under time pressure where LA- elicited a PSE at the 2nd operand. Additionally, the PSE was smaller for LA- at the solution. This suggests that categorizing multiplication facts is more effortful in LA-. In sum, very subtle language differences arise in fluent bilinguals when problems are more difficult, such as larger problems presented under time pressure in a weaker language. Critically, the effect of LA+ is at the level of response production and not access to the facts from memory.

Development is in the details: Event-related theta oscillations reveal children and adults verify multiplication facts differently.

When verifying the correctness of single-digit multiplication problems, children and adults show a robust ERP correctness effect thought to reflect similar cognitive processes across groups. Recent studies suggest that this effect is instead a modulation of the negative-going N400 component in children, reflecting access to semantic memory, and the positive-going P300 component in adults, reflecting stimulus categorization. However, the relative difference in ERP amplitude is the same for both components, more positive for correct than incorrect solutions, presenting a challenge to ascertaining the appropriate interpretation. Time-frequency analysis (TFA) of the N400/P300 window provides an objective approach to dissociating these effects. TFA measured from solution onset during single-digit multiplication verification revealed significant modulations of event-related as theta power (3-6 Hz) in both groups. Correct trials elicit less power in children (9-12 years) and more power in adults relative to incorrect trials. These findings are consistent with modulations of the N400 and P300, respectively, where opposite effects were predicted for spectral power. The ERP results further support a reinterpretation of the multiplication correctness effect. In contrast, TFA of the N400 effect elicited to a word-picture verification task revealed the same event-related theta effect in both groups, with increased power for mismatched than matched pictures. Together, these findings provide evidence for a developmental shift in cognitive processing specific to the multiplication task. Models of arithmetic should account for this overlooked difference in cognitive processing between children and adults.

The Effect of Code-Switching Experience on the Neural Response Elicited to a Sentential Code Switch.

Switching between languages, or codeswitching, is a cognitive ability that multilinguals can perform with ease. This study investigates whether codeswitching during sentence reading affects early access to meaning, as indexed by the robust brain response called the N400. We hypothesize that the brain prioritizes the meaning of the word during comprehension with codeswitching costs emerging at a different stage of processing. Event-related potentials (ERPs) were recorded while Spanish-English balanced bilinguals (n = 24) read Spanish sentences containing a target noun that could create a semantic violation, codeswitch or both. Self-reported frequency of daily codeswitching was used as a regressor to determine if the cost of reading a switch is modulated by codeswitching experience. A robust N400 to semantic violations was followed by a late positive component (LPC). Codeswitches modulated the left anterior negativity (LAN) and LPC, but not the N400, with codeswitched semantic violations resulting in a sub-additive interaction. Codeswitching experience modulated the LPC, but not the N400. The results suggest that early access to semantic memory during comprehension happens independent of the language in which the words are presented. Codeswitching affects a separate stage of comprehension with switching experience modulating the brain's response to experiencing a language switch.

When multiplying is meaningful in memory: Electrophysiological signature of the problem size effect in children.

Children are less fluent at verifying the answers to larger single-digit arithmetic problems compared with smaller ones. This problem size effect may reflect the structure of memory for arithmetic facts. In the current study, typically developing third to fifth graders judged the correctness of single-digit multiplication problems, presented as a sequence of three digits, that were either small (e.g., 4 3 12 vs. 4 3 16) or large (e.g., 8 7 56 vs. 8 7 64). We measured the N400, an index of access to semantic memory, along with accuracy and response time. The N400 was modulated by problem size only for correct solutions, with larger amplitude for large problems than for small problems. This suggests that only solutions that exist in memory (i.e., correct solutions) reflect a modulation of semantic access likely based on the relative frequency of encountering small versus large problems. The absence of an N400 problem size effect for incorrect solutions suggests that the behavioral problem size effects were not due to differences in initial access to memory but instead were due to a later stage of cognitive processing that was reflected in a post-N400 main effect of problem size. A second post-N400 main effect of correctness at occipital electrodes resembles the beginning of an adult-like brain response observed in prior studies. In sum, event-related brain potentials revealed different cognitive processes for correct and incorrect solutions. These results allude to a gradual transition to an adult-like brain response, from verifying multiplication problems using semantic memory to doing so using more automatic categorization.

Meaning to multiply: Electrophysiological evidence that children and adults treat multiplication facts differently.

Multiplication tables are typically memorized verbally, with fluent retrieval leading to better performance in advanced math. Arithmetic development is characterized by strategy shifts from procedural operations to direct fact retrieval, which would not necessitate access to the facts' conceptual meaning. This study tested this hypothesis using a combination of event related brain potentials (ERP) and behavioral measures with 3rd-5th grade children and young adults. Participants verified the solutions to simple multiplication problems (2 × 3 = 6 or = 7) and the semantic fit of word-picture pairs, separately. Children showed an N400 effect to multiplication solutions with larger (more negative) amplitude for incorrect than correct solutions, reflecting meaning-level processing. A similar ERP response was observed in the word-picture verification task, with larger negative amplitude for word-picture pairs that were semantically mismatched compared to matched. In contrast, adults showed a P300 response for correct solutions, suggesting that they treated these solutions as potential targets in over-rehearsed mathematical expressions. This P300 response was specific to math fact processing, as the word-picture verification task elicited a classic N400 in adults. These ERP findings reveal an overlooked developmental transition that occurs after fifth grade, and speak to theories of arithmetic that have been based primarily on adult data.

How do caregivers affect children's academic performance? Evidence from Primary Caregivers' Educational Attainment and Children's Performance on Standardized Assessments.

Children's performance on standardized testing are affected by a variety of external factors, such as access to resources, school environment, or primary caregiver's education. Educational inequalities, likewise, have a negative impact on the quality of education and access to resources, and impact student performance. Student outcomes and performance, hence, are multidimensional in that there are many factors that play a role in student success. For instance, previous research has shown that mother's educational attainment has an impact on their children's academic performance. By understanding the effects of primary caregivers' educational attainment on student achievement, policies can be created to promote equity in the education system. The goal of the present study is to understand the impacts of primary caregivers' educational attainment and language history on children's standardized assessment performance. We analyzed data from a large-scale study that collected demographic information (age, language background, socioeconomic status, primary caregivers' education), standardized assessment scores (math fluency, oral comprehension, working memory, phonological awareness, and vocabulary size), and performance (accuracy, response times) on a simple multiplication task. The study included a total of 176 children, and we hypothesized that children with highly educated primary caregivers were more likely to perform higher on academic assessments and the math task. Results showed that children with fathers as primary caregivers performed better on our measure of math fluency compared to children with mothers as primary caregivers. Additionally, the primary caregiver's educational attainment showed significance in performance on math fluency, oral comprehension, and math task accuracy in the "some college" and "graduate degree" category. Together, these findings suggest that primary caregivers' educational attainment can affect children's performance on standardized assessments, though future research should explore a broader population sample.

P300 amplitude and latency reflect arithmetic skill: An ERP study of the problem size effect.

The effect of arithmetic problem size is widespread in behavior (e.g., slower responses to 8 × 7 than 2 × 2). Here, we measure event related potentials (ERPs) to determine how the problem size effect unfolds under different conditions. Adults judged the correctness of simple multiplication problems (2 × 4 = 8 versus 9) that varied in size and operand number format (written digits versus spoken number words). The P300, an ERP component associated with stimulus categorization, was measured from solution onset. P300 amplitude was greatest for small and correct solutions, as expected for easily categorized stimuli. Large incorrect solutions elicited a disproportionately reduced P300, an interaction not measurable in verification behavior. Additionally, ERP measures revealed effects of operand format preceding, but not following, solution onset. The significance of these findings for theories of mathematical cognition are addressed.

Bilingual children access multiplication facts from semantic memory equivalently across languages: Evidence from the N400.

Typically, bilinguals learn multiplication facts in only one instruction language. Consequently, these facts may be represented and/or accessed as language-specific memories, requiring a qualitatively different retrieval process in their other language. Indeed, behavioral studies reveal that bilinguals verify arithmetic facts faster and better in the language of learning. Here, event-related potentials (ERPs) were used as a window into the neurocognitive processes underlying this language bias in children. ERPs were recorded while bilingual children verified the correctness of multiplication solutions. Operands were presented as spoken number words in Spanish and English, separately. Although a language bias was revealed in behavior, both languages elicited the same ERP correctness effect, an N400, reflecting similar cognitive processes in both languages. This suggests that the source of the behavioral difference is not at the level of semantic access. Our findings highlight the flexibility of the bilingual brain, especially when both languages are learned early.

When 2 × 4 is meaningful: the N400 and P300 reveal operand format effects in multiplication verification.

Arithmetic problems share many surface-level features with typical sentences. They assert information about the world, and readers can evaluate this information for sensibility by consulting their memories as the statement unfolds. When people encounter the solution to the problem 3 × 4, the brain elicits a robust ERP effect as a function of answer expectancy (12 being the expected completion; 15 being unexpected). Initially, this was labeled an N400 effect, implying that semantic memory had been accessed. Subsequent work suggested instead that the effect was driven by a target P300 to the correct solutions. The current study manipulates operand format to differentially promote access to language-based semantic representations of arithmetic. Operands were presented either as spoken number words or as sequential Arabic numerals. The critical solution was always an Arabic numeral. In Experiment 1, the correctness of solutions preceded by spoken operands modulated N400 amplitude, whereas solutions preceded by Arabic numerals elicited a P300 for correct problems. In Experiment 2, using only spoken operands, the delay between the second operand and the Arabic numeral solution was manipulated to determine if additional processing time would result in a P300. With a longer delay, an earlier N400 and no distinct P300 were observed. In brief, highly familiar digit operands promoted target detection, whereas spoken numbers promoted semantic level processing-even when solution format itself was held constant. This provides evidence that the brain can process arithmetic fact information at different levels of representational meaningfulness as a function of symbolic format.

The role of language similarity in processing second language morphosyntax: Evidence from ERPs.

This study investigated the role of L1-L2 morphosyntactic similarity in L2 learners of French. In two experiments, we manipulated the grammatical gender agreement between an adjective and noun in a sentence context. The noun either shared lexical gender across Spanish and French (Experiment 1) or did not (Experiment 2). ERPs were collected from beginner Spanish-speaking learners of French and native French speakers while they read sentences in French. The results for the native speakers revealed a P600 effect on gender agreement violations irrespective of lexical gender overlap across languages. L2 learners exhibited a negativity in the N400 time window in response to gender agreement violations that involved nouns with the same gender in their L1 and L2 (Experiments 1 and 2), whereas no difference was observed to gender agreement violations that involved nouns with contradictory gender across languages (Experiment 2). These results suggest that L2 learners at low levels of L2 proficiency rely on their L1 lexical gender system to detect gender agreement errors in L2, but engage different neurocognitive mechanisms to process similar L2 morphosyntactic knowledge.

Arithmetic memory networks established in childhood are changed by experience in adulthood.

Adult bilinguals show stronger access to multiplication tables when using the language in which they learned arithmetic during childhood (LA+) than the other language (LA-), implying language-specific encoding of math facts. However, most bilinguals use LA+ throughout their life, confounding the impact of encoding and use. We tested if using arithmetic facts in LA- could reduce this LA- disadvantage. We measured event related brain potentials while bilingual teachers judged the correctness of multiplication problems in each of their languages. Critically, each teacher taught arithmetic in either LA+ or LA-. Earlier N400 peak latency was observed in both groups for the teaching than non-teaching language, showing more efficient access to these facts with use. LA+ teachers maintained an LA+ advantage, while LA- teachers showed equivalent N400 congruency effects (for incorrect versus correct solutions) in both languages. LA- teachers also showed a late positive component that may reflect conflict monitoring between their LA+ and a strong LA-. Thus, the LA- disadvantage for exact arithmetic established in early bilingual education can be mitigated by later use of LA-.

The fox and the cabra: an ERP analysis of reading code switched nouns and verbs in bilingual short stories.

Comprehending a language (or code) switch within a sentence context triggers 2 electrophysiological signatures: an early left anterior negativity post code switch onset - a LAN - followed by a Late Positive Component (LPC). Word class and word position modulate lexico-semantic processes in the monolingual brain, e.g., larger N400 amplitude for nouns than verbs and for earlier than later words in the sentence. Here we test whether the bilingual brain is affected by word class and word position when code switching, or if the cost of switching overrides these lexico-semantic and sentence context factors. Adult bilinguals read short stories in English containing 8 target words. Targets were nouns or verbs, occurred early or late in a story and were presented alternately in English (non-switch) or Spanish (switch) across different story versions. Overall, switched words elicited larger LAN and LPC amplitude than non-switched words. The N400 amplitude was larger for nouns than verbs, more focal for switches than non-switches, and for early than late nouns but not for early than late verbs. Moreover, an early LPC effect was observed only for switched nouns, but not verbs. Together, this indicates that referential elements (nouns) may be harder to process and integrate than relational elements (verbs) in discourse, and when switched, nouns incur higher integration cost. Word position did not modulate the code switching effects, implying that switching between languages may invoke discourse independent processes.

Morphosyntax can modulate the N400 component: event related potentials to gender-marked post-nominal adjectives.

Event-related potential studies of grammatical gender agreement often report a left anterior negativity (LAN) when agreement violations occur. Some studies have shown that during sentence comprehension gender violations can also interact with semantic processing to modulate a negativity associated with processing meaning - the N400. Given that the LAN and N400 overlap in time, they are identified by their scalp distributions and purported functional roles. Critically, grammatical gender violations also elicit a right posterior positivity that can overlap temporally and potentially affect the scalp distribution of the LAN/N400. We measured the effect of grammatical gender violations in the LAN/N400 window and late positive component (LPC) during comprehension of Spanish sentences. A post-nominal adjective could either make sense or not, and either agree or disagree in gender with the preceding noun. We observed a negativity to gender agreement violations in the LAN/N400 window (300-500ms post stimulus onset) that was smaller than the semantic-congruity N400, but overlapped with it in time and distribution. The early portion of the LPC to gender violations was modulated by sentence constraint, occurring as early as 450ms in highly constraining sentences. A subadditive interaction occurred at the later portion of the LPC with equivalent effects for single and double violations (gender and semantics), reflecting a general stage of reprocessing. Overall, our data support models of language comprehension whereby both semantic and morphosyntactic information can affect processing at similar time points.

Meaning first: a case for language-independent access to word meaning in the bilingual brain.

This study aimed to determine how deeply a word is processed in the bilingual brain before the word's language membership plays a role in lexical selection. In two ERP experiments, balanced Spanish-English bilinguals read lists of words and pseudowords in Spanish and English, and performed in each language (1) a language-specific lexical decision task, e.g., respond to real words in Spanish, and (2) a language-specific category decision tasks, e.g., respond to Spanish words that refer to a person. In Experiment 1, infrequent words elicited larger negativity between 350 and 650 ms post-stimulus onset for both target and non-target languages. This indicates that language membership did not block lexical access of non-target words, contrary to previous findings. In Experiment 2, we measured the onset of the target-category P300 as a way of determining if words from the non-target language were temporarily treated as targets. When Spanish was the target language, the ERP waveforms diverged early based on semantic category (people versus non-people), indicating that non-target 'English people' words were briefly treated as potential targets. This finding indicates that meaning was accessed prior to using language membership for lexical selection. However, when English was the target language, the waveforms diverged first based on language (Spanish versus English) then semantic category. We argue that the order in which meaning or language membership are accessed may be based on the frequency of use of a bilingual's languages: the more frequently a language is used (English was more frequently used herein), the faster the words are identified as members of the language, and the greater interference it causes when it is not the target language. In brief, these findings make the case for a moment in processing when language membership matters less than meaning.

Acute stress and event-related potential correlates of attention to alcohol images in social drinkers.

OBJECTIVE: The use of alcohol to cope with stress is a major health concern, yet the neurophysiological mechanisms underlying the effects of stress on alcohol-related cognition are not well understood. This study examined changes in event-related potentials (ERPs) elicited by alcohol-related images before and after a stressor compared with a control condition. METHOD: Social drinkers (N = 75; 38 male) were assigned to one of two target subgroups for completion of an oddball task: (a) to detect alcohol targets while ignoring household object distracters and frequently presented nonsense shapes or (b) to detect object targets while ignoring alcohol distracters and nonsense shapes. ERPs were recorded before and after one of two conditions: a stressor or a nonstressful control task. RESULTS: N200 latency and amplitude changes were modulated by stress. Similarly, stress reduced P300 latencies beyond practice effects. For P300 amplitude, the target subgroup interacted with the condition such that the standard "oddball" effect was observed in the control condition but was absent in the stress condition, suggesting that stress may have interfered with the participants' cognitive efficiency, or the ability to ignore task-irrelevant stimuli. CONCLUSIONS: These findings suggest that stress influences the early stages of alcohol-related processing, an effect that may be particularly apparent in ERP latencies. These findings have implications for understanding the neural mechanisms involved with stress and alcohol cue reactivity.

Early learning shapes the memory networks for arithmetic: evidence from brain potentials in bilinguals.

Language and math are intertwined during children's learning of arithmetic concepts, but the importance of language in adult arithmetic processing is less clear. To determine whether early learning plays a critical role in the math-language connection in adults, we tested retrieval of simple multiplication in adult bilinguals who learned arithmetic in only one language. We measured electrophysiological and behavioral responses during correctness judgments for problems presented as digits or as number words in Spanish or English. Problems presented in the language in which participants learned arithmetic elicited larger, more graded, and qualitatively different brain responses than did problems presented in participants' other language, and these responses more closely resembled responses for digits, even when participants' other language was more dominant. These findings suggest that the memory networks for simple multiplication are established when arithmetic concepts are first learned and are independent of language dominance in adulthood.

Cognitive and electrophysiological correlates of the bilingual stroop effect.

The color word Stroop effect in bilinguals is commonly half the magnitude when the written and naming languages are different (between) than when they are the same (within). This between-within language Stroop difference (BWLS) is likened to a response set effect, with greater response conflict for response relevant than irrelevant words. The nature of the BWLS was examined using a bilingual Stroop task. In a given block (Experiment 1), color congruent and incongruent words appeared in the naming language or not (single), or randomly in both languages (mixed). The BWLS effect was present for both balanced and unbalanced bilinguals, but only partially supported a response set explanation. As expected, color incongruent trials during single language blocks, lead to slower response times within than between languages. However, color congruent trials during mixed language blocks led to slower times between than within languages, indicating that response-irrelevant stimuli interfered with processing. In Experiment 2, to investigate the neural timing of the BWLS effect, event related potentials were recorded while balanced bilinguals named silently within and between languages. Replicating monolingual findings, an N450 effect was observed with larger negative amplitude for color incongruent than congruent trials (350-550 ms post-stimulus onset). This effect was equivalent within and between languages, indicating that color words from both languages created response conflict, contrary to a strict response set effect. A sustained negativity (SN) followed with larger amplitude for color incongruent than congruent trials, resolving earlier for between than within language Stroop. This effect shared timing (550-700 ms), but not morphology or scalp distribution with the commonly reported sustained potential. Finally, larger negative amplitude (200-350 ms) was observed between than within languages independent of color congruence. This negativity, likened to a no-go N2, may reflect processes of inhibitory control that facilitate the resolution of conflict at the SN, while the N450 reflects parallel processing of distracter words, independent of response set (or language). In sum, the BWLS reflects brain activity over time with contributions from language and color conflict at different points.

Native experience with a tone language enhances pitch discrimination and the timing of neural responses to pitch change.

Native tone language experience has been linked with alterations in the production and perception of pitch in language, as well as with the brain response to linguistic and non-linguistic tones. Here we use two experiments to address whether these changes apply to the discrimination of simple pitch changes and pitch intervals. Event related potentials (ERPs) were recorded from native Mandarin speakers and a control group during a same/different task with pairs of pure tones differing only in pitch height, and with pure tone pairs differing only in interval distance. Behaviorally, Mandarin speakers were more accurate than controls at detecting both pitch and interval changes, showing a sensitivity to small pitch changes and interval distances that was absent in the control group. Converging evidence from ERPs obtained during the same tasks revealed an earlier response to change relative to no-change trials in Mandarin speakers, as well as earlier differentiation of trials by change direction relative to controls. These findings illustrate the cross-domain influence of language experience on the perception of pitch, suggesting that the native use of tonal pitch contours in language leads to a general enhancement in the acuity of pitch representations.

Why the white bear is still there: electrophysiological evidence for ironic semantic activation during thought suppression.

Much research has focused on the paradoxical effects of thought suppression, leading to the viewpoint that increases in unwanted thoughts are due to an ironic monitoring process that increases the activation of the very thoughts one is trying to rid from consciousness. However, it remains unclear from behavioral findings whether suppressed thoughts become more accessible during the act of suppression. In the current study, event-related potentials were recorded while participants suppressed or expressed thoughts of a focus word during a simple lexical decision task. Modulations in the N400 component reported here demonstrate the paradoxical effects occurring at the semantic level during suppression, as well as some evidence for the rebound effect after suppression periods. Interestingly, semantic activation was greater for focus words during suppression than expression, despite differences in the N1 window suggesting that expression elicited greater perceptual processing than suppression. Results provide electrophysiological evidence for the Ironic Process model and support recent claims of asymmetric network activation during thought suppression.