Shanna Kousaie

Conflict monitoring and resolution: Are two languages better than one? Evidence from reaction time and event-related brain potentials

An advantage for bilingual relative to monolingual young adults has been found for cognitive control tasks, although this finding is not consistent in the literature. The present investigation further examined this advantage using three tasks previously found to be sensitive to the effect. Furthermore, both behavioral and event-related brain potential (ERP) measures were included. Monolingual (n=25) and highly proficient bilingual (n=26) young adults completed a Stroop, Simon, and Eriksen flanker task while electrophysiological recording took place. Behaviorally there were no language group differences on any of the tasks. The ERP measures demonstrated differences between monolinguals and bilinguals with respect to conflict monitoring, resource allocation, stimulus categorization, and error-processing; however, these differences were not consistent across tasks. Given the similar behavioral performance across the groups the observed differences in brain responses may not represent an advantage for bilinguals. The results are discussed with respect to previous findings.

Ageing and bilingualism: Absence of a “bilingual advantage” in Stroop interference in a nonimmigrant sample

Previous research has found an advantage for bilinguals relative to monolinguals on tasks of attentional control. This advantage has been found to be larger in older adults than in young adults, suggesting that bilingualism provides a buffer against age-related declines in executive functioning. Using a computerized Stroop task in a nonimmigrant sample of young and older monolinguals and bilinguals, the current investigation tried to replicate previous findings of a bilingual advantage. A bilingual advantage would have been demonstrated by smaller Stroop interference (i.e., smaller increases in response time for incongruent than for neutral trials) for bilinguals than for monolinguals. The results showed that bilingual young adults showed a general speed advantage relative to their monolingual counterparts, but this was not associated with smaller Stroop interference. Older adults showed no effect of bilingualism. Thus, the present investigation does not find evidence of a bilingual advantage in young or older adults and suggests limits to the robustness and/or specificity of previous findings.

Executive function and bilingualism in young and older adults

Research suggests that being bilingual results in advantages on executive control processes and disadvantages on language tasks relative to monolinguals. Furthermore, the executive function advantage is thought to be larger in older than younger adults, suggesting that bilingualism may buffer against age-related changes in executive function. However, there are potential confounds in some of the previous research, as well as inconsistencies in the literature. The goal of the current investigation was to examine the presence of a bilingual advantage in executive control and a bilingual disadvantage on language tasks in the same sample of young and older monolingual anglophones, monolingual francophones, and French/English bilinguals. Participants completed a series of executive function tasks, including a Stroop task, a Simon task, a sustained attention to response task (SART), the Wisconsin Card Sort Test (WCST), and the digit span subtest of the Wechsler Adult Intelligence Scale, and language tasks, including the Boston Naming Test (BNT), and category and letter fluency. The results do not demonstrate an unequivocal advantage for bilinguals on executive function tasks and raise questions about the reliability, robustness and/or specificity of previous findings. The results also did not demonstrate a disadvantage for bilinguals on language tasks. Rather, they suggest that there may be an influence of the language environment. It is concluded that additional research is required to fully characterize any language group differences in both executive function and language tasks.

ERP measures of semantic richness: the case of multiple senses.

Semantic richness refers to the amount of semantic information that a lexical item possesses. An important measure of semantic richness is the number of related senses that a word has (e.g., TABLE meaning a piece of furniture, a table of contents, to lay aside for future discussion, etc.). We measured electrophysiological response to lexical items with many and few related senses in monolingual English-speaking young adults. Participants performed lexical decision on each item. Overall, high-sense words elicited shorter response latencies and smaller N400 amplitudes than low-sense words. These results constitute further evidence of the importance of semantic richness in lexical processing, and provide evidence that processing of multiple related senses begins as early as 200 milliseconds after stimulus onset.

A behavioural and electrophysiological investigation of the effect of bilingualism on aging and cognitive control

ABSTRACT Given previous, but inconsistent, findings of language group differences on cognitive control tasks the current investigation examined whether such differences could be demonstrated in a sample of older bilingual adults. Monolingual and bilingual older adults performed three cognitive control tasks that have previously been used in the literature (i.e., Stroop, Simon and flanker tasks) while brain electrophysiological recordings took place. Both behavioural (response time and accuracy) and event‐related brain potentials (ERPs; N2 and P3 amplitude and latency) were compared across the two language groups. Processing differences between monolinguals and bilinguals were identified for each task, although the locus differed across the tasks. Language group differences were most clear in the Stroop task, with bilinguals showing superior performance both behaviourally and electrophysiologically. In contrast, for the Simon and flanker tasks there were electrophysiological differences indicating language group processing differences at the level of conflict monitoring (Simon task only) and stimulus categorization (Simon and flanker tasks), but no behavioural differences. These findings support suggestions that these three tasks that are often used to examine executive control processes show little convergent validity; however, there are clear language group differences for each task that are suggestive of superior performance for bilinguals, with behavioural differences emerging only in the linguistic Stroop task. Furthermore, it is clear that behavioural measures alone do not capture the language group effects in their entirety, and perhaps processing differences between language groups are more marked in a sample of older adults who are experiencing age‐related cognitive changes than in younger adults who are at the peak of their cognitive capacity. HighlightsMonolingual and bilingual older adults were compared on 3 cognitive control tasks.Language group differences were demonstrated, but were variable, across the 3 tasks.Electrophysiological measures may detect more subtle language group differences.Language group differences may be more evident in older than younger adults.The Stroop, Simon, and flanker cognitive control tasks are not inter‐changeable.

Performance on the Boston Naming Test in Bilinguals

OBJECTIVES We examined performance on the Boston Naming Test (BNT) in older and younger adults who were monolingual English or French speakers, or bilingual speakers of English and French (n=215). METHODS Monolingual participants completed the task in their native language, and bilingual participants completed the task in English, French, and bilingual (either-language) administrations. RESULTS Overall, younger and older monolingual French speakers performed worse than other groups; bilingual participants performed worst in the French administration and approximately two-thirds of bilingual participants performed better when responses were accepted in either language. Surprisingly, however, a subset of bilinguals performed worse when responses were accepted in either language as compared to their maximum score achieved in either English or French. This either-language disadvantage does not appear to be associated with the degree of balanced bilingualism, but instead appears to be related to overall naming abilities. Differential item analysis comparing language groups and the different administrations identified several items that displayed uniform and/or non-uniform differential item functioning (DIF). CONCLUSIONS The BNT does not elicit equivalent performance in English and French, even when assessing naming performance in monolingual French speakers using the French version of the test. Scores were lower in French overall, and several items exhibited DIF. We recommend caution in interpreting performance on these items in bilingual speakers. Finally, not all bilinguals benefit from an either-language administration of the BNT.

The bilingual advantage: Elusive but worth the effort?

The notion of a bilingual advantage in cognitive function is an attractive hypothesis that has clearly garnered significant interest from the scientific community. Beyond simply implying that the ability to communicate in more than one language in a relatively proficient way over many years leads to advantages in cognition, it suggests that training in one domain, i.e., language, results in advantages in a domain-general faculty, i.e., general executive control. Beyond this, and not discussed in detail in by Paap, Johnson, and Sawi (2015), the bilingual advantage has been purported to confer advantages as people age and experience changes in cognitive function (e.g., Bialystok, Craik, Klein, & Viswanathan, 2004; Gold, Kim, Johnson, Kryscio, & Smith, 2013; Luk, Bialystok, Craik, & Grady, 2011). Furthermore, some research suggests that merely being bilingual can result in a delay in the onset of Alzheimers disease symptoms (e.g., Bialystok, Craik, Binns, Ossher, & Freedman, 2014; Bialystok, Craik, & Freedman, 2007; but see Chertkow et al., 2010; Crane et al., 2010; Zahodne, Schofield, Farrell, Stern, & Manly, 2014 for alternate findings). It is exciting to think that something as natural as language could have such dramatic effects on cognitive functioning over the course of the lifespan, and potentially buffer against age-related cognitive decline. It is not surprising that many researchers have pursued this hypothesis in an attempt to understand its magnitude and mechanism(s). Paap et al. provide an extensive review of the published findings, and conclude that current evidence does not support thehypothesisof a cognitiveadvantage forbilinguals.Weagree that theeffects of bilingualismmayhavebeenoverstated in the literature, although we believe that there are indeed undeniable differences between monolinguals and bilinguals. What remains unclear is whether these differences lead to measurable changes in domain-general executive function and, if so, under what circumstances. One important consideration with respect to the failure to find behavioural advantages in executive control for bilinguals is that much of the research uses samples of young adults, who are at the peak of their cognitive functioning. However, it is probable that differencesemergemostclearly incaseswherecognitive functioning is sub-optimal, suchas inolderadultswhomaybeexperiencing age-related cognitive declines. That is, when cognition is suboptimal there is room for bilingualism to exert an effect, whereas in young adults there is no room for improvement because they are at the height of cognitive function. A second major issue raised in the target article relates to brain-based evidence that ostensibly supports an advantage for bilinguals in the absence of behavioural evidence. Paap et al. point out that “reorganization to accommodate bilingualism does not logically need to result in more efficient performance” (p. 29). We agree that behavioural advantages are required in order to ascertain that a brain-based difference represents a true advantage. However, brain-based differences, even in the absence of behavioural advantages, remain an interesting and important area of study. Even in the absence of behavioural differences, any observed differences in measures of brain structure or function suggest that bilinguals and monolinguals are performing the same tasks differently, despite arriving at the same endpoint. This speaks to language-induced brain plasticity and suggests a possible source of cognitive differences later in the lifespan. In addition, advances in cognitive neuroscience methods that are potentially more sensitive and/or of higher resolution (e.g., resting-state functional connectivity, global and local efficiency measures) may prove useful in further elucidating

Alterations in resting-state activity relate to performance in a verbal recognition task.

In the brain, resting-state activity refers to non-random patterns of intrinsic activity occurring when participants are not actively engaged in a task. We monitored resting-state activity using electroencephalogram (EEG) both before and after a verbal recognition task. We show a strong positive correlation between accuracy in verbal recognition and pre-task resting-state alpha power at posterior sites. We further characterized this effect by examining resting-state post-task activity. We found marked alterations in resting-state alpha power when comparing pre- and post-task periods, with more pronounced alterations in participants that attained higher task accuracy. These findings support a dynamical view of cognitive processes where patterns of ongoing brain activity can facilitate –or interfere– with optimal task performance.

Age-related Differences in Interlingual Priming: A Behavioural and Electrophysiological Investigation

ABSTRACT Reaction time (RT) and the N400 ERP component were measured to examine age-related differences in bilingual language processing. Although young bilinguals appear to access both languages simultaneously (i.e., non-selective access), little is known about language selection in older adults. The effect of language context on language selectivity was investigated using interlingual homographs (IH; i.e., words with identical orthography but distinct semantic features in two languages, e.g., coin meaning ‘corner’ in French and ‘money’ in English). Younger and older French/English bilinguals were presented with triplets of letter strings comprised of a language context cue, an IH, and a target word, in a lexical decision semantic priming task. RT and ERP results support non-selective language access in young adults; however, the older bilinguals used the language context cue to bias their reading of the IH. Results are discussed in terms of age-related changes in language processing and context use in bilinguals.

Effects of Semantic Richness on Lexical Processing in Monolinguals and Bilinguals.

The effect of number of senses (NoS), a measure of semantic richness, was examined in monolingual English speakers (n = 17) and bilingual speakers of English and French (n = 18). Participants completed lexical decision tasks while EEG was recorded: monolinguals completed the task in English only, and bilinguals completed two lexical decision tasks, one in English and one in French. Effects of NoS were observed in both participant groups, with shorter response times and reduced N400 amplitudes to high relative to low NoS items. These effects were stronger in monolinguals than in bilinguals. Moreover, we found dissociations across languages in bilinguals, with stronger behavioral NoS effects in English and stronger event-related potential (ERP) NoS effects in French. This finding suggests that different aspects of linguistic performance may be stronger in each of a bilingual’s two languages.