A number of studies have found that older adults aren’t as good at certain visual tasks compared to younger adults. Mental rotation, for example, is both slower and less accurate. But other studies have found that for certain types of mental rotation, older adults do just as well as younger adults. The dividing line, these researchers argued, was based on whether the viewer was rotating or the objects themselves were rotating.
So in a classic mental rotation task like Shepard and Metzler’s, older adults don’t do as well, but in many other tasks, their performance isn’t much different from younger adults.
But a new study by a team led by Mélanie Joanisse challenges the notion that the frame of reference — objects rotating relative to the viewer or to themselves — isn’t the key factor. Instead, they suggest, it has to do with how that rotation is being processed.
They had 24 college students (average age 23) and 24 older adults (average age 72.1) sit on a desk chair in the center of a small round room. Seven different drawings (a cup, shoe, book, box, plate, jar, and hairbrush) were spaced at even intervals on the wall. The viewers memorized the positions of the objects, and then were blindfolded, rotated in the chair, and asked to point to one of the four nearest neighbors of the object they were facing. The key to the study was how they were rotated:
The solid lines represent when viewers actually rotated, while the dashed lines represent when they only imagine rotating. So, how accurate were they at pointing to objects in these conditions? Here are the results:
In the Control and Updating conditions, there was only a small, nonsignificant difference between older adults and younger adults. But in the Ignoring and Imagining conditions, younger adults performed significantly better than older adults.
Why? The researchers say that the key difference between older adults and younger adults is the ability to imagine rotations, whether the rotations are centered around themselves or around other objects. When they themselves actually rotate, there is very little difference between older and younger adults.
Mélanie Joanisse, Sylvain Gagnon, Joshua Kreller, Marie-Claude Charbonneau (2008). Age-related differences in viewer-rotation tasks: Is mental manipulation the key factor? Journal of Gerontology: Psychological Sciences, 63B (3), 193-200