Tip-of-the-tongue (TOT) experiences are common and become more frequent in old age. But what causes them? Deborah Burke of Pomona College and her team found that when we don’t use words often enough, our brain’s associations with that word become weakened. Tip-of-the-tongue moments became more frequent as the gray matter in the area called the left insula, an area of the brain that has been implicated in sound processing and production, declined.
“Words aren’t stored as a unit,” Burke says. “Instead you have the sound information connected to semantic information, connected to grammatical information, and so on. But the sounds are much more vulnerable to decay over time than other kinds of information, and that leads to the TOT experience.”