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Poster E62, Friday, November 10, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

A longitudinal behavioral and fMRI study of second language learning

Kaitlyn M. Tagarelli1, Xiong Jiang2, Aaron J. Newman1, Kyle F. Shattuck2, Aron K. Barbey3, John W. VanMeter2, Kara Morgan-Short4, Alison Mackey2, Peter E. Turkeltaub2, Elissa L. Newport2, Michael T. Ullman2;1Dalhousie University, 2Georgetown University, 3University of Illinois at Urbana-Champaign, 4University of Illinois at Chicago

Millions of adults all over the world attempt to learn second languages (L2s). This task is notoriously difficult, and many struggle to attain high proficiency, let alone retain it, which is the ultimate goal of L2 learning. Understanding the neural mechanisms involved in language learning may help shed light on why it is so difficult for adults, as well as on how it can be made easier. While growing evidence suggests that neurocognitive changes occur over the course of L2 learning, it is still unclear which brain structures and cognitive mechanisms are involved at which proficiency levels. Additionally, our understanding of how the brain retains an L2 is in its infancy. This study combines behavioral and fMRI measures to longitudinally examine L2 learning from low to high proficiency, and then again after a period of no exposure to the L2 (“retention”). Nineteen English native speakers (Mage = 20.6 ± 2.81; 9 females) were trained on a subset of Basque over three three-hour sessions, and 16 returned approximately one month later for one session to test their L2 retention. Vocabulary and grammar training occurred via a forced-choice picture-matching task, providing a continuous behavioral measure during training. fMRI data were continuously acquired during all grammar training, as well as during word-level training and a grammaticality judgment task (GJT) in early (Day 1), late (Day 3), and retention sessions. fMRI analyses were conducted using FEAT in FSL, and clusters were considered significant when Z > 2.3, k > 25 voxels, and corrected p < 0.05. Learners achieved very high proficiency in vocabulary and reasonably high proficiency in grammar. For word and grammar learning, activation (compared to a sensorimotor control task) was broadly and bilaterally distributed in the brain and decreased overall but only slightly from Day 1 to Day 3, and then substantially at retention, suggesting a decrease in processing effort as learners became more proficient the L2. However, activation in some structures, particularly in the medial temporal lobe for words and the basal ganglia for grammar, increased, suggesting more specific roles for these areas according to language domain. For the GJT, activation for violation compared to control sentences was focused around the right IFG (BA44) and middle temporal lobe on Day 1. On Day 3, activation in these areas and their left hemisphere homologues increased, and there was additional activation in the right putamen. This suggests that participants’ ability to distinguish good and bad sentences increased over the course of learning, eventually recruiting areas within the procedural memory system that have been shown to be involved in L1 and L2 grammar processing, at least at high proficiency. At retention, learners showed more activation for correct sentences compared to violations, specifically in the left postcentral gyrus. Overall, these findings help to broaden our understanding of the neurocognition of L2 learning and retention, have implications for neurocognitive theories of L2, and demonstrate the importance of longitudinal approaches and integrating neural and behavioral methods in language learning research.

Topic Area: Multilingualism

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