What was I looking for?

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

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

As annoying as it is, this kind of forgetfulness is usually normal, says Dr. Sharon Sha, a professor of neurology at Stanford University.

When we ignore information we just learned or thoughts we just had, it’s usually because our brains didn’t store them as long-term memories in the first place, Dr. Sha said.

We don’t always make memories

As you go about your daily life, your brain holds information in a temporary state called working memory, says David Gallo, a professor of psychology at the University of Chicago. For example, if you’re on a phone call while following a dinner recipe, you’ll have to juggle multiple tasks in your working memory at the same time, he said.

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

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

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 take notes and close your computer without saving, your notes are gone forever,” he said.

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

While these mistakes may seem frustrating in the moment, they are actually essential to your daily functioning, says Lynne Reder, professor emeritus of psychology at Carnegie Mellon University.

If our brains coded everything we saw, heard, smelled or felt, we would have no working memory left for things like walking, talking or listening.

How to remember

Sometimes it’s easy to remember information, said Dr. Sha. For example, if you feel a strong emotion such as fear or trauma at the moment you learn something, you are more likely to remember it later. This explains why many people remember exactly where they were on September 11, she said.

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

Repeat and recite. Repeating information, especially in new ways, can help with memory retention, says Ronald Davis, a professor of neuroscience at the University of Florida. When we hear, see, recite aloud, or write down a word, we are given several opportunities to encode that word through different pathways in the brain.

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

Assigning meaning. Remembering random information can be particularly challenging, said Dr. Ship owner. Therefore, it is sometimes easier to remember names associated with certain characteristics or qualities. For example, we can remember a dog named Rusty if he had a rust-colored coat.

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

Sing along. Likewise, remembering can become easier if the information is aligned properly, said Dr. Sha. For example, you may remember an advertising jingle, even if it is for a product you would never buy.

Neuroscientists are still learning why music helps, but Dr. Sha said “tagging” memories with tunes sets them in different parts of the brainmaking them more likely to stick around.

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

For example, if you need to buy a holiday gift for your daughter, you can imagine yourself buying the item or imagine how happy your daughter will be when she opens the gift.

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

Regular activities such as aerobics, weight lifting, stretching or even short walks can also improve memory, both in the short term and over time, experts say.

Keeping your heart healthy through exercise will keep your brain healthy, Dr. Gallo said. “This can help you age gracefully and ensure that your memory continues to function optimally at every stage of life.”

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