Now, What Was I Looking For?

Q: Some thoughts vanish from my brain as soon as I think of them. Why can’t I remember things I just knew? And how can I improve my short-term memory?

Perhaps you smile and shake hands with a new acquaintance, and then promptly forget the person’s name. Or maybe you walk into your kitchen to do … something. What was it again?

Exasperating as it is, this type of forgetfulness is usually normal, said Dr. Sharon Sha, a professor of neurology at Stanford University.

When we blank on information we just learned or thoughts we just had, it’s typically because our brains didn’t save them as long-term memories to begin with, Dr. Sha said.

We don’t always make memories

When going about your daily life, your brain holds information in a temporary state called working memory, said David Gallo, a professor of psychology at the University of Chicago. Having a phone conversation while following a dinner recipe, for instance, involves juggling multiple tasks in your working memory at once, he said.

Most people can only hold about four or five thoughts or tasks in their working memories at a time, Dr. Gallo said.

But unless those thoughts go through a brain process called encoding, he added, they won’t be saved permanently in your long-term memory.

This works like a computer’s “save” function, said Dr. Scott Small, director of the Alzheimer’s Disease Research Center at Columbia University. “If you’re taking notes and you close your computer without saving, your notes are gone forever,” he said.

The encoding process involves creating meaningful connections between brain cells and requires ample working memory. So if you’re preoccupied with introducing yourself to someone new or deciding what you’ll say next, your brain won’t encode information like the new name you hear — and you’ll promptly forget it.

While these lapses may seem frustrating in the moment, they’re actually essential for your day-to-day functioning, said Lynne Reder, a professor emeritus of psychology at Carnegie Mellon University.

If our brains encoded everything we saw, heard, smelled or felt, we wouldn’t have any working memory left for things like walking, talking or listening.

How to remember

Sometimes it’s easy to remember information, Dr. Sha said. If you feel a strong emotion like fear or trauma in the moment you learn something, for instance, you’re more likely to recall it later. This explains why many people remember exactly where they were on Sept. 11, she said.

But there are other tricks and tactics, experts say, that can help us purposefully save memories for the long-term.

Repeat and recite. Repeating information, especially in new ways, can assist with memory storage, said Ronald Davis, a professor of neuroscience at the University of Florida. When we hear, see, recite aloud or write down a word, we get several chances to encode that word using different pathways in the brain.

Studies also suggest that writing new information by hand — be it on paper or a tablet with a digital stylus — can activate more of the brain than typing can, further strengthening our memories. The more times we repeat something, the more likely we are to remember it, Dr. Davis said.

Assign meaning. Remembering arbitrary information can be particularly challenging, Dr. Reder said. That’s why it is sometimes easier to recall names that are connected to certain characteristics or qualities. We might remember a dog named Rusty if it had rust-colored fur, for example.

“If you meet someone named Michelle who’s from Florida, you can imagine a Florida beach with a seashell, which sounds like Michelle,” Dr. Gallo said. “Now you can associate that name with a context, visual image and rhyme.”

Sing along. On a similar note, remembering can come easier when information is set to tunes, Dr. Sha said. You might remember an advertisement jingle, for example, even if it’s for a product you’d never buy.

Neuroscientists are still learning why music helps, but Dr. Sha said that “tagging” memories with tunes might move them into different parts of the brain, making them more likely to stick.

Create a visual or emotional cue. If you’re trying to remember to perform a specific task, Dr. Sha said that it can help to imagine yourself doing it or thinking about how it’ll make someone feel.

If you need to buy a holiday gift for your daughter, for instance, you can picture yourself purchasing the item, or imagine how happy it’ll make your daughter when she opens the present.

Prioritize sleep and exercise. As with many things in life, it’s more challenging to encode new information when you’re sleep deprived, Dr. Gallo said, so it’s crucial that you get enough rest.

Regular activity such as aerobic exercise, weight lifting, stretching or even short walks can also enhance memory, both in the short term and over time, experts said.

Keeping your heart healthy through exercise helps keep your brain healthy, Dr. Gallo said. “This can help you age gracefully, and keep your memory functioning optimally at any stage of life.”

Caroline Hopkins is a health and science journalist based in Brooklyn.