A new study has revealed the while older people maintain their mental flexibility, they are unable to filter out irrelevant information like younger people do, as their brains learn more than they need to.
The research led by Brown University undermines the conventional wisdom that the brains of older people lack flexibility, or "plasticity," but highlight a different reason why learning may become more difficult as people age, calling it "plasticity and stability dilemma."
Corresponding author of the study, Takeo Watanabe, said that they found that the stability was problematic. Human learning and memory capability is limited, and people don't want older, existing important information that is already stored to be replaced with trivial information.
Watanabe and his team conducted the study on two groups: one of 10 people between 67 and 79 years old and another of 10 people ages 19 to 30 for an experiment. Over a nine-day period, they trained on a simple visual exercise: Shown a quick sequence of six symbols - four letters and two numerals - volunteers were asked to report the numerals they saw. Their performance on a test at the end of training was compared to their score on a pre-test.
The results of the testing were telling. Older people improved as much as younger people on the relevant task of identifying the two numerals.
When it came to the irrelevant skill of discerning the prevailing direction of dot movement, older people learned that, too, even when it was at its most obvious. Younger people, meanwhile, only showed improvement on discerning movement when it was insidiously subtle. If it was clear, they recognized it and filtered it out.
The idea that the most obvious signals were the most easily filtered, suggested that the difference between older and younger learners was a matter of attention.
The researchers therefore subjected the volunteers to another test for the ability to find a relevant stimulus amid a number of distractors. Older people did notably worse than younger ones, adding evidence that the attentional systems for filtering out irrelevant stimuli were indeed weaker in older learners. Importantly, the poorer an older subject was at the ability to filter out irrelevant stimuli, the more irrelevant stimuli the subject learned.
The study is published in Current Biology.
