Nearly everyone has tip-of-the-tongue moments, but bilinguals seem especially prone to these momentary lapses in vocabulary, says Jennie Pyers, a psychologist at Wellesley College in Massachusetts.
One possible explanation is that similar-sounding words compete for our brain’s attention. Since bilinguals know twice as many words as monolinguals, there’s more chance for tip-of-the-tongue experiences.”
— Why your brain just can’t remember that word - life - 08 June 2009 - New Scientist