Using event related potentials to study language control and processing in bilingual adults

Language is a structured communication system that is comprised of speaking, writing and non-verbal gestures, and it plays a crucial role in the formation of communities. Although the exact number is unknown, there are approximately 5 to 7 thousand different languages being spoken in the world and in this day and age speaking more than one language has become a necessity in both educational and professional life. People who are bilingual show remarkable control and flexibility in the way they determine when they will use which language. They can limit their language output to just one or they can opt to switch between languages. This linguistic control and processing occurs at a very rapid rate. Bilingualism is the perfect example to show how neural networks are wired when a skill is acquired from birth versus when it is acquired later in life when neural pathways serving the native language have already been established. The three main goals of brain imaging are to understand where the language is processed in the brain, and when and how these linguistic processes take place. In the past twenty years Event Related Potentials (ERPs) have been used as the method of choice to process the speed of language production with their high temporal resolution. The present study has investigated electrophysiological changes during picture naming tasks in native language (L1) and second language (L2) in sequential bilingual adults whose native language is Turkish. The study has included 15 volunteers. ERPs have been recorded via electrocap through 19 channels and these recordings have been analyzed in terms of latency and frequency. ERP analysis has revealed statistically meaningful differences in latency in the mixed language condition when switching from L1 to L2 as opposed to from L2 to L1. A similar difference has been observed between the blocked language condition for both L1 and L2, and the mixed language condition for the same languages respectively. Statistically meaningful frequency differences are also noted between cognate and non-cognate words when they are named in L2. The present study is thought to contribute to bilingual research in language activation and lexical selection by offering data in a new language, namely Turkish.