Methodological Issues in Research on Bilingualism, Cognitive Aging, and Cognitive Reserve

Laura Zahodne and Jennifer Manly

Studies of the relationship between bilingualism and dementia have yielded discrepant results.

This talk will explore four methodological issues that may help to explain these discrepancies,

clarify our understanding of the relationship between bilingualism and cognitive function in

older adults, and guide future research studies of bilingualism and cognitive reserve. First,

designs to distinguish causation from association in studies of bilingualism and dementia risk

will be discussed. Second, the critical step of distinguishing cognitive level from cognitive

change, and interpreting cross-sectional versus longitudinal or incidence studies, will be

discussed. Many variables, such as general intellectual ability, socioeconomic status and life

experiences, are difficult to disentangle from bilingualism and could also influence cognitive

aging trajectories and risk for dementia. These confounds are more problematic in studies

based in memory disorders clinics than in community-based studies of older adults. Therefore,

the third methodological issue discussed will be how results change when we are better able to

isolate and quantify the independent effect of bilingualism on executive function, cognitive

decline or dementia incidence. Historical changes in immigration policies and conditions in the

native country may be powerful tools to understand the conditions and experiences that travel

along with bilingualism and how they relate to cognitive aging. Fourth, the potential

advantages of assessing bilingualism skills on a continuum for studies of cognitive reserve and

cognitive aging trajectories will be discussed.

What Is Reserve and How Do We Get It?

Yaakov Stern, PhD

The concept of reserve has been put forward to account for individual differences in

susceptibility to age-related brain changes and pathologic changes, such as those that occur in

Alzheimer’s disease. The concept of cognitive reserve suggests that the brain actively attempts

to cope with brain damage by using pre-existing cognitive processing approaches or by enlisting

compensatory approaches. This talk will review the theory underlying the concept of reserve,

and ideas of brain reserve, cognitive reserve and brain maintenance; and epidemiologic evidence

for the various lifestyle factors that might contribute to reserve.

Do bilingual children perform more efficiently in different experimental tasks than their monolingual peers?

Klara Marton

Studies on executive functions in bilingual children show mixed findings. Some authors report no group difference between bilingual and monolingual children in executive functions, such as attention control (e.g., Antón et al., 2014), whereas others show superior performance in bilingual children compared to their monolingual peers on the same tasks (e.g., Yang, Yang, & Lust, 2011). What are the sources of these contradictory findings? Several contributing factors have been identified in the bilingual literature. The role of the following factors will be discussed in this presentation: 1. individual language proficiency; 2. language context (societal level); 3. cultural background; 4. overall speed of processing. Based on our own research findings, we will show how the above factors interact with implicit learning, performance monitoring, and interference control in school-age children.

What Is (Are) Executive Function(s)? Insights From Individual Differences Research

Naomi Friedman

Executive functions are high-level cognitive processes that enable control over thoughts and actions through their regulation of lower-level processes. They are central to many areas of psychology, including research on psychopathology, development, aging, and bilingualism, to name a few. Yet there is still considerable variability in how researchers measure these abilities, and how they conceptualize the cognitive and neural mechanisms that underlie individual differences in performance on executive tasks. Part of this variability stems from the fact that executive functioning is not a single ability, but rather is a family of interrelated but separable abilities. I will present an overview of one well-replicated model, the unity/diversity model, which describes the relationships among three of the most frequently studied executive functions: response inhibition, working memory updating, and task switching. The model is so named because these abilities show some unity, in that a common factor influences individual differences in all three, but also show diversity, in that there are also specific factors that influence individual differences in working memory updating and task switching. After discussing the genetic and environmental influences on these unity and diversity components, and what they may be measuring in terms of cognitive mechanisms, I will discuss implications and recommendations for incorporating them into bilingualism research.

Investigating grammatical processing in bilinguals: The case of morphological priming

João Veríssimo & Harald Clahsen (Potsdam Research Institute for Multilingualism, Germany)

Much previous work on the advantages and disadvantages of bilingualism has focussed on vocabulary or the processing of simple words. From a linguistic perspective, however, vocabulary is a rather peripheral aspect of the knowledge of language, and claims about the effects of bilingualism that are based on tasks that tap only into lexical aspects may not necessarily hold for bilingual language processing as a whole.

In this talk we will discuss methods for investigating grammatical processing in bilinguals, focusing on the use of morphological priming studies. We will present a methodological approach that relies on (i) linguistic (in our case, morphological) theory for the construction of experimental materials, (ii) a design that allows for direct (within-experiment, within-participant and within-item) comparisons of the critical conditions, and (iii) data analysis techniques that make both linear and non-linear gradient effects visible. We believe that these considerations are not only relevant for morphological priming experiments, but for studying bilingual language processing more generally.

We illustrate our approach using new data from a large-scale study with more than 90 bilingual participants from the Turkish/German community in Berlin investigating age effects in bilingual grammatical processing. The main discovery of this study was a selective age-of-acquisition (AoA) effect for grammatical processing abilities that (by using statistical modelling techniques) can be precisely delimited to a particular age range. Our participants all learnt Turkish from birth and German at different ages, spanning an AoA range from birth to about 35 years of age. We tested them on both inflectional and derivational priming in German. While derivational priming was found not to be affected by AoA and was present across the whole AoA range, inflectional priming showed a gradual AoA-related decline, but only from the ages of 5-6 onwards. Under the assumption that inflection is largely grammatical in nature (in that it simply spells out morphosyntactic features) whereas derivation is lexically-based (in that it creates new words), our results suggest that the critical period for language acquisition might be restricted to grammar, rather than applying to language as a whole. We will discuss the implications of this finding for bilingualism research, including the role of executive function and other non-linguistic factors in bilingual language processing.

Referring expressions and executive functions in child and adult bilinguals

Antonella Sorace (University of Edinburgh)

Reference tracking requires the language user to both infer appropriate pronoun-referent mappings and dynamically update the discourse model following a change of referent status. Recent research on the so-called ‘syntax-pragmatics interface’ (e.g. Sorace & Serratrice 2009; Sorace 2011; 2011; Chamorro, Sorace & Sturt 2015) shows that pronouns and other referring expressions requiring efficient updating of context-dependent information (a) develop late in bilingual children; (b) remain variable even in highly proficient second language speakers, and (c) become unstable in speakers experiencing native language attrition from a second language. In contrast, more narrowly linguistic structure types that are less dependent on the integration of unpredictable contextual information are more stable in all three bilingual populations. I will explore a possible account of these phenomena based on effects of the bilingual experience on executive functions and how these effects may in turn interact with bilingual language processing in specific ways.