Experts at Stirling and Edinburgh universities have found that the various speech breaks like "ums", "ers" and "ahs," known as "disfluencies," actually force a listener to pay attention.
For the study, the research team asked volunteers to listen to a series of sentences, including a number which had disfluencies. They then carried out a series of tests to calculate how much the listeners could remember.
Analysis showed that slotting in the "ers" in fact had a considerable effect on how well the subjects could recall what was said.
Researchers said that up to an hour after hearing typical sentences, volunteers got 62 per cent of words correct where there had been a disfluency in the sentence, as compared to 55 per cent of sentences where there had not been any stumbles.
"A disfluency is an interruption to the predicted ritual of things. It's like we are saying to ourselves 'I'd better pay attention now, because what I thought was going to happen isn't going to happen,'" the Daily Mail quoted Dr Martin Corley, of Edinburgh University's School of Philosophy, Psychology and Language Sciences, as saying.
The researchers are now studying whether words such as "like" operate in a similar way to disfluencies.