Tests carried out on a group of 60 people came up with the finding that older people are not as skilled as younger people at keeping a conversation on track.
People are more likely to deviate off the topic during conversation the older they become, the study suggested.
The researchers found people who are more likely to wander in conversation tend to be more knowledgeable, but are less skilled at selecting the most relevant parts of their wisdom to use.
The researchers, from the University of Edinburgh, used computerised tests – one to measure the ability to choose relevant information and another to quantify knowledge – to analyse 840 speech samples from the group, whose ages ranged from 18 to more than 80 years old.
Participants were first given a series of subjects to speak about for one minute. The researchers then measured the coherence of the participants’ speech – how likely they were to talk about the subject given, rather than producing irrelevant information.
Then they were given a series of tests to measure thinking skills. One of these measured how knowledgeable they were, by testing their vocabulary. Another tested their ability to focus on specific aspects of their knowledge, for example by matching familiar objects based on their colour.
The team found, on average, that older people were not as skilled as younger people at selecting which information to share.
People with less coherent speech tended to have more knowledge, but were less good at selecting the most relevant elements of their knowledge.
The researchers say the study “helps understand the underlying cognitive mechanisms that can cause changes in the quality of social interactions as people age”.
Lead researcher Paul Hoffman, of the university’s School of Philosophy, Psychology and Language Sciences, said: “Previous studies had found that older people tend to be less coherent in conversation but the reason for this change wasn’t clear.
“Here we found older people are more knowledgeable than young people but are less skilled at selecting which aspects of their knowledge are most important. We all get distracted by irrelevant thoughts from time to time when we’re speaking, but our results suggest that this happens more often as we get older and accumulate more knowledge.”