We’ve all been there: you’re having a casual, run-of-the-mill conversation, and all of a sudden you just… can’t… quite… think of… the… umm… hoo boy.

At this point, you may try to make a joke to play off the situation, and if you’re of a certain age, that joke probably involves the phrase “senior moment” and gets a sympathetic laugh. But the truth is that everyone has trouble remembering things from time to time, no matter their age.  It might surprise you to learn, for example, that 90% of the time I talk about him, I can’t remember what the heck Kevin Spacey’s name is. I can always remember the movies I’ve seen him in, but his name just slips into the ether.

Up until now, many had attributed this “tip of the tongue” phenomenon to something called phonological blocking, which occurs when you try to think of a specific word and some other, similar-sounding word comes up in the brain instead. The new word blocks your ability to access the correct word. In my case, this theory would suggest that I can’t remember Kevin Spacey’s name because my brain is mixing him up with Kevin Costner (a compelling theory, I might add!)

But according to a recent study conducted by the Laboratory for Language & Cognitive Neuroscience at San Diego State University, phonological blocking may not be responsible for those “senior moments.” Instead, it seems that the “tip of the tongue” phenomenon occurs because of the way our brains organize information according to how frequently the information is used.

According to the Karen Emmorey, who headed up the study, the brain is constantly shifting information around according to how often you access it. A simplified way to think about it is to imagine that your brain is like a huge library full of filing drawers. The drawers you look in most often (i.e. those with pertinent, current information like your kid’s birthday or your favorite actor) move closer to the front of the library, where you can access them more easily. The drawers you rarely access (like names of old friends or history facts you learned in high school) can end up way in the back, collecting dust.

Interestingly, the “tip of the tongue” phenomenon isn’t limited to just speaking. People who communicate via American Sign Language (ASL) experience a similar issue from time to time, which is  cleverly dubbed “tip of the finger.” In fact, those who use ASL often get stuck remembering a certain sign but can remember what part of the body is used to make the sign – the same way that people using a spoken language can remember the first letter in a word but not the entire word.

Scientists had previously observed that bilingual people seem to have more “tip of the tongue/finger” moments than monolinguals. They attributed this to the idea that bilinguals have double the phonological blockers because they have blockers in two languages, not just one. To test this theory, Emmorey and colleagues studied people who were bilingual in ASL and English. If the phonological blocker theory held true, Emmorey thought, then people who were bilingual in a signed and a spoken language would not have double phonological blockers, since only the spoken language employs phonemic language units, and ASL employs gestural ones.  But, she found that even those who are bilingual in English and ASL have more frequent “tip of the tongue” moments than monolinguals.  This suggests that people who are bilingual in any two languages have trouble finding words not because of phonological blocking, but because they use all words less frequently- since they are splitting brain space (“file cabinets”) between two languages.

While we all experience the “tip of the tongue” phenomenon from time to time, as we age it does seem to happen more frequently. People who have a lot of trouble finding words may have a deficit in what neuropsychologists call fluency or word finding. The IMPACT Study, a controlled clinical trial conducted by Mayo Clinic and USC, showed that doing the Brain Fitness Program helped people with word finding, among other things.

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