Derek Burnett
Derek Burnett is a Contributing Writer at Bottom Line Personal, where he writes frequently on health and wellness. He is also a contributing editor with Reader’s Digest magazine.
Your trainer at the gym introduces you to a new member, and five minutes later you realize you’ve completely forgotten their name. You get behind the wheel of your car and experience a brief panic as it takes you a moment to remember where you were planning on going. In the morning, your wife tells you about a new show you’d really like, but in the afternoon when you plop down in front of the TV, you can’t for the life of you remember what it was called. All of these are examples of short-term memory lapses, and they can be disheartening and even scary, leaving you to wonder, “Have I suffered short-term memory damage? Is this the beginning of dementia?”
The answer to both questions is probably no. Most short-term memory lapses are normal and not worth worrying much about.
What makes one thing a short-term memory and another a long-term memory? Is there some kind of time cutoff, where, say, if you remember something for a week or more it gets classified as a long-term memory?
Not exactly. To understand the difference between these two kinds of memory, it helps to learn a little about how memories are formed.
Every memory you have was created in a three-stage process. Those three stages are encoding, storage, and retrieval. To explore how they work, let’s imagine a scenario in which a child who’s been waiting eagerly at his grandmother’s house sees his parents walk in, newly returned from the hospital, holding his new baby sister. It is the first time he’s seen the baby, and it’s a moment that he’ll remember for the rest of his life.
Encoding…When his parents come through the door with the infant, the older child’s senses are firing off reams of data input to his brain. The texture of the new baby’s car seat, the smell of the infant’s head, the blissful exhaustion on his mother’s face, even the scuffs on his father’s shoes and the feel of his grandmother’s loving hand on his shoulder. All of these impulses gather in an area of his brain called the hippocampus, which combines them into a single memory.
Storage…So far, these impressions comprise a “working memory” or short-term memory. They give the child the necessary data to navigate through the moment. If someone asked him to close his eyes and say what color his mother’s shirt was, he would have no problem doing so because he’s still very much engaged in the moment at hand. But by default, working memories are held onto for only as long as they’re useful, and then they’re discarded and replaced by others that pertain to whatever is happening in the next moment. Of course, some of these become long-term memories, often because they’re important enough that we replay them and reinforce them in our minds.
Retrieval…Once something is stored as a long-term memory, there are two ways in which we can access it. “Recall” gives us direct access to the memory because it is so fresh or so frequently accessed that it is within conscious reach. “Recognition” uses cues to pull up the memory. In the case of our young boy meeting his baby sister for the first time, perhaps in his 20s he’ll encounter a chair upholstered with the same fabric of his baby sister’s car seat, and this cue will bring the memory of that moment rushing back upon him.
So why do our working memories sometimes fail us? The answer is that both the encoding and the storage processes can be disrupted.
Let’s take the example where you’ve just been introduced to someone at the gym but can’t remember their name five minutes later. The name may not have been properly encoded because you were paying more attention to the person’s smile or clothing than to their name. Or perhaps it was encoded just fine but then promptly discarded as you turned your attention to your plan for the day’s workout.
Similar disruptions to encoding and storage could have happened with our other examples, as well. When you get behind the wheel of your car and realize you can’t remember where you were headed, you most likely have simply been too distracted by other concerns to have kept your intended destination at the forefront of your working memory. When you sit down in front of the TV and can’t remember the title of the show your wife recommended, it may be that you were only half-interested when she suggested it, and thus you failed to encode or store the title properly.
Even the retrieval process can get disrupted. Sometimes the reason you can’t think of where it was you’d planned on going is because you’re simultaneously worrying about an unpaid bill, a relationship problem, or that knocking sound your car has been making lately…or, on a more positive note, maybe you’re mentally reliving the great weekend you just spent with your grandkids.
As you can see, most of these problems with short-term memory are of a similar nature having to do with lack of attention, lack of importance, or distraction. Often, we’re willing to ascribe short-term memory problems to aging, but it’s worth considering that older people often have more to think about. It may not be that your brain is failing you, but that your attention and cognitive priorities have shifted. Chances are, with directed effort, you could easily recall the person’s name in the gym, the title of the TV show, or where you’d planned on going in the car.
All of the above examples represent normal short-term memory lapses. Sometimes, of course, people’s short-term memories fail for more serious reasons. If you worry that your lapses aren’t normal, talk to your doctor about it. Perhaps your physician will recommend testing to see if you’re suffering from some form of cognitive impairment, including subjective cognitive decline (SCD), which affects roughly one in nine adults. Many people worry that if they have memory problems, and especially if they have cognitive impairment, that means they have Alzheimer’s. But most people experiencing occasional lapses don’t have cognitive impairment, and only about 40% of those who do will go on to develop Alzheimer’s.
