No matter what your politics, if you're over the age of 50, you probably cringed with empathy — or at least a little bit of self-recognition — when John McCain blanked on the name of former Secretary of State George Shultz, one of his key supporters and someone he's known for decades, on "Meet the Press" last Sunday.

After all, who among us in the baby boomer (or older) demographic group hasn't had the frustrating (and, let's face it, often humiliating) public experience of temporarily forgetting the name of someone we know very well?

Neuroscientists refer to such a moment as a tip-of-the-tongue (TOT) experience — the inability to recall a name (or other word) accompanied by the overwhelming feeling that you know the name and are just on the verge of producing it. They've studied the phenomenon extensively — and with reassuring results: TOTs are quite common and usually quite normal, particularly as we grow older.

Secretary what's-his-name
McCain's TOT moment was a classic one. After rattling off the names of four other secretaries of state, he paused, unable to come up with Shultz's name. Realizing he couldn't remember it, McCain went through the list a second time — and still drew a blank. With a big sigh, he then gave up and referred to Shultz simply as "one other." But his mind kept rummaging around in its memory stores for the right name. Suddenly, after his interviewer, Tom Brokaw, started to speak, McCain blurted out, "George Shultz!" (You can almost see the light bulb go off in his head.) "George," he added, "I'm sorry I left you out." (Apologies are de rigueur for TOT moments.)

You can watch McCain's TOT episode here:

A universal thingamajig
We can't know how often McCain struggles with names, but in studies that use memory diaries people report experiencing TOTs one to four times a week. Many researchers believe, however, that those studies underestimate the phenomenon's true incidence rate. People tend to ignore TOTs that are quickly resolved or that involve trivial information. ("Would you please pass me that thingamajig over there?" "You mean the TV remote?")

Interestingly, TOTs are so universal that most languages have a word or phrase to describe them. Italians call them sulla punta della lingua, for example, and the Koreans use the delightfully creative phrase hyeu kkedu-te-mam-dol-da, which means "sparkling at the end of my tongue."

Whatchamacallit theories
Scientists used to ascribe to a "clogged drain" theory about TOTs. They thought words with similar meaning or sounds "clogged" the brain's access to the sought-after word. Now, though, they tend toward a "too-weak-of-a-link" theory: The brain can usually remember something about the wanted word — maybe its first letter or its number of syllables — but not enough information to get the word off the tip of the tongue.

This theory helps explain another well-known characteristic of TOTs: the way in which the elusive word eventually and mysteriously pops to mind. It may be that a phonetic clue — another word with a similar-sounding syllable, for example — subconsciously provides a strong-enough link to trigger a memory of the forgotten word. In one study, people were able to successfully resolve TOTs by up to 50 percent when given a list of phonologically similar words.

Watch — or, rather, listen — to McCain's TOT moment again. Just before he shouted, "George Shultz!" Tom Brokaw said the word endorsed, which has a shared sound (or) with George. That may have been the phonetic clue that finally released the secretary of state's name from McCain's memory stores.

What's age got to do with it?
Unfortunately for McCain — and for the rest of us — we become more prone to TOT experiences as we age. Scientists have a couple of theories about why: 1) the brain's memory systems may weaken with age, or 2) older people may have more stored knowledge to stumble over as their brains search for a specific word or name.

I know which theory I prefer.