Blind people have a better ability to remember speech compared to sighted people, but visual ability makes no difference in how well a person remembers sound effects, according to a new study1 by Johns Hopkins University and the University of California, Irvine.
It’s interesting that people who are blind only showed an advantage with verbal memory. Blind people may use language like a mental tool to remember information,
said senior author Marina Bedny, an associate professor of psychology and brain sciences at Johns Hopkins whose work regularly compares blind and sighted individuals’ brains.
Researchers did two memory tests, involving 20 blind adults and 22 blindfolded sighted adults, to investigate if blind participants would outperform sighted ones at remembering spoken sounds.
First, participants listened to series of letters, followed by a delay. Then they heard either the same series or a “foil” series where a letter is replaced or put into the wrong position. Participants then judged whether the second series of letters was the same as the first.
For the second test, they listened to letters while solving mathematical equations with proposed answers. Participants determined if equations solutions were correct, followed by reciting back the letters.
Repurposed Visual Cortex
As the researchers expected, blind participants outperformed sighted ones on speech memory. The results from another testing phase, which required solving mathematical equations and recalling letters, confirmed researchers’ predictions.
Blind participants again remembered more letters than sighted participants despite being forced to multitask mentally.
On a daily basis, blind people use their memory much more to remember things, while sighted people can rely on visual clues to recall information. We think blind people’s advantages on the verbal tests stem from increased practice remembering information. The brain area responsible for vision in sighted people, the visual cortex, is repurposed for other functions in blind people. Perhaps it enhances blind people’s language processing,
said lead author Karen Arcos.
In another experimental phase, participants listened to two streams of sound effects and were asked if the sounds matched.
The researchers used sound effects such as tones and high-pitched beeps rather than everyday sounds to ensure sounds couldn’t be labelled with words. On this task, blind and sighted people performed essentially the same.
By using meaningless sound effects, we prevented participants from using language to remember them this lowered blind people’s usual memory advantage,
Bedny is now studying what enables blind people to outperform sighted people at remembering words, letters, and numbers. She plans to examine if the “visual” cortex contributes to improved memory for speech and language in those born blind.
- Arcos, K., Harhen, N., Loiotile, R. et al. Superior verbal but not nonverbal memory in congenital blindness Exp Brain Res 240, 897–908 (2022). ↩︎