The ebb and flow of language proficiency and brain activation: A case study on a Japanese-English bilingual returnee

Thematic Section: Japanese-English bilinguals in flux

attrition, referential choice, crosslinguistic influence, vocabulary, form similarity

Hideyuki Taura, Ritsumeikan University, Kyoto
Amanda Taura, Setsunan University, Osaka
This study explores how language attrition is mitigated when the individual returns to the original linguistic milieu for a set amount of time, from the perspectives of language proficiency and brain activation.
We tracked a Japanese-English returnee student for 5 years by collecting data once a year: (1) base-line data at the incubation time (INC) of 3 months back in Japan from the USA where she had resided from age 6;11 to 14;01 for 8 years, (2) a year later (INC 1.03 years), (3) two years later (INC 2.00 years), (4) three years after the original base-line data, but only 2 months (INC 0.02 months) after having moved back from an English speaking environment for a further year, and (5) four years later (INC 1.02). She was 14;04 and 18;04, respectively at the first and fifth data collection sessions.
Data collection was two-fold – both linguistic data and neuro-linguistic data were gathered yearly. Linguistic data involved a spontaneous oral narrative task and a spontaneous written test (TOWL-3), which were analyzed from conventional viewpoints such as fluency and vocabulary. Meanwhile, neuro-linguistic data were collected while the participant was engaging in verbal fluency tasks (VFT) on an fNIRS machine (Shimadzu OMM-3000) to observe oxygenated hemoglobin flow in Broca’s area in the prefrontal cortex.
The results showed an overall gradual decline in the first three years, however, at the time of the fourth data collection, re-residing effects were present in her vocabulary selection, indicated by a more sophisticated word choice on both oral narrative and writing tasks, a more fluent speech delivery, and less energy needed in the brain when carrying out the VFT, whereas the overall writing skills showed no such effects. The results are synthesized to come to a general conclusion at the presentation.