Ramesh Kumar Mishra builds upon Valian's suggestions by arguing that research studies should shift to comparing bilinguals of different proficiencies instead of bilinguals to monolinguals. She argues things like exercising and video game playing can affect executive function, and since they are unrelated to language, they must be controlled for. Kaushanskaya and Prior respond to Valian that it is not only the lack of uniformity in defining executive function, but also the difficulty in defining bilingualism which make it problematic to draw strong conclusions about the effects of bilingualism on executive function.