February 6, 2023 – Can't find your keys? Lost your glasses? Don't know where you parked your automobile?
We all lose things now and again. And everyone knows the usual advice: Think about once you last had the item. Despite this common experience, recent research from Brigham and Women's Hospital shows that our ability to recollect where and after we last saw something – our spatial and temporal memory – is surprisingly good.
“It is known that we have enormous recognition memory for objects,” says study co-author Dr. Jeremy Wolfe, professor of ophthalmology and radiology at Harvard Medical School. In other words, we're good at recognizing objects that we've got seen before. “For example, if observers look at 100 objects for 2 to 3 seconds each, they can distinguish those 100 old images from 100 new ones with an accuracy of well over 80%.”
But remembering what the keys appear to be doesn't necessarily enable you find them. “We often want to know when and where we saw [an object],” says Wolfe. “So our goal was to measure these spatial and temporal memories.”
In a series of experiments reported in Current BiologyWolfe and colleagues asked study participants to recall objects placed on a grid. They looked at 300 objects (pictures of things like a vase, a wedding dress, camouflage pants, a wetsuit) and were asked to recall each one and say where it was on the grid.
About a third of the people were able to remember 100 or more locations by choosing either the correct square on the grid or one right next to it. Another third remembered 50 to 100, and the rest remembered fewer than 50.
In the real world, the results would probably be even better, “because nobody gives up and thinks, 'I can't remember where something is. I'm just going to guess on this silly experiment,'” Wolfe says.
Later, they were shown the objects one at a time and asked to click on a timeline to indicate when they had seen them. In 60 to 80 percent of cases, they were able to indicate when they had seen an object within 10 percent of the correct time. That's much better than the 40 percent they would have achieved if they had guessed.
The results build on previous research and expand our understanding of memory, says Wolfe. “We knew that individuals can remember where certain things are. However, nobody had tried to quantify this memory,” he says.
But wait a minute: If we're so good at remembering where and when, why is it so hard for us to find lost items? Probably not. We only feel this way because we focus on the failures and overlook the many successes.
“The [study] tells us something about how we all know where a whole bunch of things are in our world,” says Wolfe. “We often notice after we fail – 'Where are my keys?' – but on a traditional day we usually access an enormous memory successfully.”
Next, the researchers want to investigate whether spatial and temporal memories correlate with each other – if you're good at one, are you good at the other? So far, “this connection appears to be reasonably weak,” says Wolfe.