Ageing vision easily distracted

Older people can take longer to sort a scene’s important visual information from the irrelevant, a new study has found.

The researchers behind the finding explain that this is the visual equivalent of an older adult’s struggles to stay on topic while telling a story.

A younger brain is able to inhibit other thoughts while storytelling, sticking to the pertinent facts necessary to get through to the punch line. But a decline in neural inhibition means an older brain frequently goes off on a tangent, so a story beginning about one topic can conclude on a completely separate note.

This inhibition ability is also important when our brain processes an object or scene, lead author and York University researcher, Dr John Anderson, highlighted.

Dr Anderson and his research team gave a series of white shapes on black backgrounds to two groups of people – one with an average age of 20 and the other with an average age of 66.

The 50 study participants were asked to classify the white, inner shape in each image as either meaningful or familiar or unknown and novel.

Some images showed a meaningful white, inner object, such as an apple, while a second group had a meaningful black outlines, such as the faces of two seahorses facing each other. The rest were completely meaningless.

To interpret these images, the brain’s inhibitory system must discount the interpretation of the outer image for the inner, white shape.

The results, published in the Journal of Vision, showed that, while both groups came to the same conclusions on the familiarity of the white objects, the older adults took a longer time to reach these conclusions.

Dr Anderson emphasised: “This research may have practical importance for how perception changes with age as well, particularly in situations of low visibility –possibly fog, bad lighting etc – when the identity of shapes is harder to discern.”

Image credit: University of Arizona