Decline in Visual Perception Linked to Age-Related Cognitive Problems

People experience a decline in cognitive abilities with age. A new study suggests that the decrease in intelligence is linked to a decline in visual perception.

The study, conducted by researchers at University of Edinburgh, shows that the ageing brain processes visual information slower than a young brain. This slowdown in visual perception leads to a decline in scores on tests that assess intelligence.

The research also shows that visual decision-making processes lie at the core of intelligence. Scientists argue that instead of complex tests, simple tasks that involve visual decision making can be used to assess cognitive abilities of not just old people, but also children.

The study was based on data from 600 healthy old people. participants were shown brief flashes of one of two shapes on a screen while researchers measured the time that the subjects took to distinguish between the flashes. Participants were tested at ages 70, 73, and 76. The study found that the so-called "inspection time" might be related to changes in intelligence in old people.

"The results suggest that the brain's ability to make correct decisions based on brief visual impressions limits the efficiency of more complex mental functions," said Stuart Ritchie of the University of Edinburgh. "As this basic ability declines with age, so too does intelligence. The typical person who has better-preserved complex thinking skills in older age tends to be someone who can accumulate information quickly from a fleeting glance."

Previous research has shown that old people with a high IQ are more likely to discern between the two flashes of images faster than other people. The new study shows for the first time that decline in the ability to tell two images apart is directly linked to cognitive abilities.

"What surprised us was the strength of the relation between the declines," Ritchie said in a news release. "Because inspection time and the intelligence tests are so very different from one another, we wouldn't have expected their declines to be so strongly connected."

The study is published in the journal Current Biology.