Have you ever walked into a room and forgotten why you walked in, or were ready to speak but suddenly realized you had no idea what to say? of the human brain it normally balances countless inputs, thoughts, and actions, but sometimes it seems to cycle. So what actually happens when we forget what we were just thinking?
Understanding why we forget first requires understanding how we do memory works – and debunking some memory myths.
“Memory is not just one thing” Susanne Jaeggia professor of psychology at Northeastern University, told Live Science. “There are very different components of memory, and they are also linked to different cognitive processes.”
In this case, it is important to recognize two different types of memory: long-term memory and working memory. Long-term memories are a broad, multifaceted category of memories that include knowledge, experiences, and skills stored in the brain for long periods of time—from hours to a lifetime. On the other hand, thoughts in working memory only pass through the mind for seconds or minutes at a time.
Related: ‘Short-term memory illusions’ can distort human memories just seconds after events, study suggests
Working memory is like the “outline of conscious thought,” Earl K. Millera professor of neuroscience at MIT, told Live Science. Each piece of new information, internal dialogue, and sensory input routes through working memory, and certain characteristics of working memory likely explain why we forget those thoughts.
First, working memory has a very limited capacity. There has been some debate about exactly what the limit is and how to test for it, but psychologists estimate that people can only maintain about four THE seven “chunks” of information—such as letters, numbers, words, or phrases—into their working memory at a time. Instead of being aware of all these “chunks” simultaneously, the brain bounces from one idea to another, making it more likely that a person will get lost in the shuffle, Miller explained.
Second, the brain quickly deletes irrelevant things from working memory to make room for new information. So, unless those short-term memories are transferred into long-term memories (a process called consolidation), they will soon drop out of conscious thought.
Because the brain isn’t really capable of multitasking, Miller said, it has to “judge” different thoughts as our working memory goes to different ideas. This requires conscious effort and attention, which is overseen by the brain’s prefrontal cortex, a region involved with complex learning, decision-making and reasoning. If attention is focused on just one of those thoughts or diverted elsewhere, the brain loses track of previous thoughts.
“It hits one of the ‘balls,’ and that’s why you forget things,” Miller said.
The brain is especially likely to “off the ball” from working memory when it is drowsy or impaired by alcohol or other drugs. Age is also a factor; Miller said working memory function peaks in a person’s 20s and begins to decline during middle age.
But for those who regularly struggle with thoughts that slip into their heads, Jaeggi and Miller have some evidence-based advice.
To avoid forgetting so many things in the first place, Miller advised against multitasking. “When you think you’re multitasking, what you’re doing instead is, you’re cheating,” he said, and cheating makes forgetfulness more likely.
Jaeggi gave a tip on what to do when a thought is already gone.
“Re-creating the context can help,” she said. This means going back to the room you were in before, or revising your thoughts. These context clues can give the brain the extra push it needs to get a few seconds back into working memory and retrieve the thought before it disappears completely.
