AbstractsLanguage, Literature & Linguistics

Cognitive and neural mechanisms of bilingual decision making: From visual word processing to decisions under risk

by Yulia Oganian

Institution: Freie Universität Berlin
Year: 2015
Posted: 02/05/2017
Record ID: 2067298
Full text PDF: http://edocs.fu-berlin.de/diss/receive/FUDISS_thesis_000000101043


Bilingual individuals read in their second language (L2) and frequently make decisions based on information perceived in their L2. Compared to monolinguals, visual word recognition in bilinguals bears additional aspects that may also affect later stages of processing. Their integration into neurocognitive models of single word reading and decision making still leaves many open questions. In particular, bilingual word recognition entails the ability to recognize the language membership of a word, and to map letter strings to lexical representations and phonology of the appropriate language, whereby the underlying mapping rules can be different and even contradictory across languages. Furthermore, following these perceptual aspects of word recognition, the perceived information is often used as a basis for higher level, non-perceptual processes, such as decision making under risk. A prominent example for the effects of linguistic framing on decision making is the stronger preference for risky choices when negative outcomes are emphasized than when positive consequences are explicitly stated (the framing effect). The effects of foreign language use on processes influencing the framing effect, most prominently affective processing and cognitive control, has been postulated, but direct evidence for these effects is scarce. This dissertation's research investigates cognitive and neuronal aspects of bilingual visual word recognition and decision making, using the case of bilingual individuals with native language German (L1) and second language English (L2). Study 1 isolated the effects of word and pseudoword length (i.e. number of letters) on the dynamics of sublexical encoding and lexical access in German and English, using a diffusion model of reaction times (RTs) in lexical decisions. Study 2 investigated whether language membership decisions and naming in a language-ambiguous context are influenced by continuous sublexical (bigram frequencies) and lexical (orthographic neighborhood size) similarity of a letter string to German and English words. This was extended to an investigation of the neuronal correlates of language similarity statistics and language membership representations in Study 3, using functional magnetic resonance imaging (fMRI). Study 4 investigated whether a reduced framing effect during foreign language use is due to reduced affect or increased cognitive control. Study 1 showed that sublexical encoding of words and pseudowords during lexical decision takes longer for longer stimuli, whereas lexical access is accelerated for words but slowed for pseudowords. Sublexical length effects in English were larger than previously found in native speakers of English, whereas the effects of length on lexical access in English were similar to those previously reported for English. These findings suggest that sublexical but not lexical processing remains tuned to the orthographic structure of the L1. In Studies 2 and 3, graded sublexical and lexical language similarities to each of the two languages biased…