So I’m currently learning two languages, aside from English and my native language, Portuguese. I’ve been noticing I forget words mid-sentence, or I get stuck in conversation with a foreign language in mind, trying to translate to my native language.

Is there any backup science that suggests that learning two or more languages can affect your native speech skills or vocabulary?

  • 1
    No answers probably means this isn't common enough to have been identified and studied. Anecdotally I can say that I have noticed interference between L2 and L3 but not much of an effect on L1. I know of native English speakers working in a non-native English speaking environment who have adopted non-idiomatic patterns used by the other speakers around them, e.g. I want that you do xyz. I think that is a different kind of effect though - more language change than difficulty with an acquired language.
    – rchivers
    Mar 31, 2020 at 15:01
  • 4
    Look up "language attrition" to find references to deteriorating L1 under certain circumstances. Apr 1, 2020 at 7:08
  • Code switching and semantic aphasia share neural pathways.
    – livresque
    Apr 1, 2020 at 7:33

1 Answer 1


An often mentioned anecdote supporting the answer "yes, it can" is Joseph Conrad's report that he had lost some facility with his native Polish (as a result of becoming a great master of English prose).

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