Poster #111 - A Lateralized Readiness Potential (LRP) Study of Response Preparation and Inhibition in Bilingual and Monolingual Children

• In Event: 1-005 - Poster Session 01
  In Poster Session: PS 01 Section - Language, Communication

Integrative Statement

Inhibition is a core executive function (EF) skill involving the control of attention, behavior, thoughts, and emotions. The inhibition skills of bilingual populations have come into focus recently, with a number of studies suggesting that early exposure to a second language shapes inhibition skills over the lifespan. Inhibition involves two dissociable processes: ‘interference suppression’ and ‘response inhibition’ (Brydges et al., 2013). In children, bilingualism is thought to specifically shape interference suppression but not response inhibition skills (Martin-Rhee & Bialystok, 2008). However, current tasks used to study inhibitory control development do not allow precise disentanglement of the two sub-processes. The current study used electrophysiological techniques to examine whether early bilingualism may shape neural mechanisms of response inhibition in school-aged children, and is the first to neurally examine and compare response inhibition mechanisms in bilingual and monolingual children.
92 participants (44 BLs; 48 MLs) ranging from 6–8 years old (M (SD) = 6.98 (0.57) yrs) participated in the study. Inhibitory control was measured using the nonverbal Animal Size Stroop Task (Bryce et al. 2011) while high-density EEG was recorded. Lateralized Readiness Potentials (LRPs) were then computed from ERP segments derived from incongruent (Stroop) trials. The LRP waveform is an electrophysiological marker of motor-preparation before motor-responses. LRPs typically feature an initial positive deflection indexing incorrect motor-response preparation, and secondary negative deflections indexing correct motor-response preparation. Based on previous developmental LRP literature, variables of interest were peak amplitudes and latencies, peak onset and cessation latencies (latencies at 75% of peak amplitude), and transition duration between positive and negative deflections. We compared bilingual and monolingual children’s LRP waveform morphology, Stroop effects experienced, and RTs and accuracies on incongruent (Stroop) trials. Age (in months) and family SES data were also collected.
Both language groups showed the expected LRP waveform morphology consisting of an initial positive deflection and a secondary negative deflection. However, one sample t-tests showed that the initial positive deflection was only significant in the bilingual group, whereas the secondary negative deflection was significant in both bilinguals and monolinguals, as expected (Fig. 1). Bivariate correlation analyses showed that older children had faster RTs, and smaller Stroop effects, and earlier negative LRP peak latencies, as expected. Children from lower SES families showed lower accuracy, longer RTs, and larger Stroop effects, as expected. Relevant correlates were included as covariates where applicable. Language groups showed behavioral equivalency on the Animal Size Stroop Task, however two-tailed independent samples t-tests showed earlier negative peak latencies (p=.056), later positive peak cessation (p=.035), and negative peak onset latencies (p=.026), in bilinguals compared to monolinguals. That is, bilinguals’ correct response preparation process peaked earlier than monolinguals, while their incorrect response preparation ended and correct response preparation started later than monolinguals. Positive peak onset and negative peak cessation latencies were equivalent across groups. Results suggest that early bilingualism shapes response inhibition in addition to interference suppression, unlike what is currently theorized. Neural investigations in children are needed to understand how bilingualism shapes developing mechanisms of inhibition, and EF more broadly.

Authors

• Srishti Nayak, Princeton University
  Presenting Author

• Hiba Salem, Boston University
  Non-Presenting Author

• Diletta Mittone, University of Maryland
  Non-Presenting Author

• Amanda Tarullo, Boston University
  Non-Presenting Author