Things start to get really strange, however, when looking at what happens in the minds of people who speak more than one language fluently. "With bilinguals, you are literally looking at two different languages in the same mind," explains Panos Athanasopoulos, a linguist at Lancaster University in the UK. "This means that you can establish a causal role of language on cognition, if you find that the same individual changes their behaviour when the language context changes."