Feb. 6, 2023 -- Can't find your keys? Misplaced your glasses? No clue where you parked your car?
We all lose things from time to time. And we've all heard the standard-issue advice: Picture when you had the object last. Despite this common experience, new research from Brigham and Women's Hospital reveals that our ability to recall where and when we last saw something -- our spatial and temporal memory – is surprisingly good.
“It is well known that we have massive recognition memory for objects,” says study co-author Jeremy Wolfe, PhD, a professor of ophthalmology and radiology at Harvard Medical School. In other words, we're good at recognizing objects we've seen before. “For example, after viewing 100 objects for 2 to 3 seconds each, observers can discriminate those 100 old images from 100 new ones with well over 80% accuracy.”
But remembering what your keys look like won't necessarily help you find them. “We often want to know when and where we saw [an object],” Wolfe says. “So our goal was to measure these spatial and temporal memories.”
In a series of experiments, reported in Current Biology, Wolfe and colleagues asked people in the study to remember objects placed on a grid. They viewed 300 objects (pictures of things like a vase, a wedding dress, camo pants, a wetsuit) and were asked to recall each one and where it had been located on the grid.
About a third of the people remembered 100 or more locations, by choosing either the correct square on the grid or one directly next to it. Another third remembered between 50 and 100, and the rest remembered less than 50.
Results would likely be even better in the real world “because no one gives up and decides 'I can't remember where anything is. I will just guess in this silly experiment,'” Wolfe says.
Later, they were shown items one at a time and asked to click on a time line to indicate when they had seen them. Between 60% and 80% of the time, they identified when they had seen an object within 10% of the correct time. That's a lot better than the 40% they would have achieved by guessing.
The findings build on previous research and expand our understanding of memory, Wolfe says. “We knew that people could remember where some things were located. However, no one had tried to quantify that memory,” he says.
But wait: If we're so good at remembering the where and when, why do we struggle to locate lost objects so much? Chances are, we don't. We just feel that way because we tend to focus on the fails and overlook the many wins.
“This [study] is showing us something about how we come to know where hundreds of things are in our world,” Wolfe says. “We tend to notice when this fails -- 'where are my keys?' -- but on a normal day, you are successfully tapping a massive memory on a regular basis.”
Next, the researchers plan to investigate whether spatial and temporal memories are correlated -- if you're good at one, are you good at the other? So far, “that correlation looks rather weak,” Wolfe says.