Tip of the tongue experiences, also referred to as TOT, are word finding failures where people are briefly unable to produce a word they are sure they know. Normal aging increases probability of TOT, as does being multilingual. In aging, increased number of TOTs may be related to gray matter atrophy in the left insula, an area which is involved in phonological production (producing speech and understanding language).

The part of the brain that makes one frustrated while experiencing TOT is likely the anterior cingulate cortex. The ACC is part of pain processing, the experience of unpleasantness and frustration, and avoidance learning as a reaction to pain. Studies show that in situations where words are retrieved successfully, an ACC response is not indicated, whereas TOT experiences with retrieval failures do indicate and ACC response.

In terms of language production, first your brain must choose what concept you are trying to put into words. This is often called the message level of language production. Next, in the functional level, your brain must retrieve the words needed to convey that chosen message. Next, the phrases and words must be arranged properly in the positional and phonological encoding levels. Finally, in the speech gesturing level, you must actually pronounce the words. TOTs are interruptions in this process, wherein the concept you are trying to produce is clear, but the retrieval stage is interrupted.