Why confidence in memories declines with age

Cluttering of the brain is one reason older people are more susceptible to manipulation, researchers said

Older people struggle to remember important details because their brains cannot resist the irrelevant "stuff" they soak up subconsciously, thereby making them less confident in their memories, a study says.

Using bio-sensors to look at brain activity, the researchers saw that older participants wandered into a brief "mental time travel" when trying to recall details.

This journey into their subconscious veered them into a cluttered space that was filled with both relevant and irrelevant information.

This clutter led to less confidence, even when their recollections were correct, the study said.

Cluttering of the brain is one reason older people are more susceptible to manipulation, the researchers said.

"This memory clutter that's causing low confidence could be a reason why older adults are often victims of financial scams, which typically occur when someone tries to trick them about prior conversations that didn't take place at all," said lead researcher Audrey Duarte, associate professor of psychology at Georgia Institute of Technology in the US.

The findings appeared online in the journal Neuropsychologia.

For the study, the researchers showed that older adults (60 years and up) and college students a series of pictures of everyday objects while electroencephalography (EEG) sensors were connected to their heads.

Each photo was accompanied by a colour and scene. Participants were told to focus on one and ignore the other. An hour later, they were asked if the object was new or old, and if it matched the colour and the scene.

Neither age group was very good at recalling what they were told to ignore. Both did well remembering the object and what they were supposed to focus on.

"But when we asked if they were sure, older people backed off their answers a bit. They weren't as sure," Duarte said.

The researchers noticed differences in brain activity between the young and old. Older adults' brains spent more time and effort trying to reconstruct their memories.

"While trying to remember, their brains would spend more time going back in time in an attempt to piece together what was previously seen," she said.

"But not just what they were focused on -- some of what they were told to ignore got stuck in their minds," Duarte said.