Micro-research on cognitive abilities and communication skills while abroad.
In the early period of adaptation to the new environment in which an immigrant begins to communicate primarily using a foreign language, a decline in cognitive abilities appear.
Major factors are (a) the increased workload due to the unusually large use of a foreign language, and (b) the foreign language knowledge level. An immigrant gradually begins to think in two languages, sometimes languages change in turn, other times both are used while building a single thought.
As a result, the brain starts saving resources: the person is using simplified alternatives to native words and phrases during the thought process, which subsequently leads either to a longer logical conclusion or even begins to lead the person on a false conclusion trail. The effect is espesially noticeable if a speaker has low linguistic competence. Language influences how meaning is constructed1.
What another research finds, listeners of non-native speakers also have to adjust "by increasing their reliance on top-down processes"2, hence, they extract less information.