Concentrating closely on a conversation or a juicy bit of gossip, can make people deaf to other sounds - even someone shouting the words "I'm a gorilla", a study has discovered.
Eavesdropping volunteers (particularly female) completely failed to notice the shouting 'gorilla man' while their attention was focused elsewhere.
“This research demonstrates that we can miss even very surprising and distinctive sounds when we are paying attention to something else.”
In a famous demonstration of the effect, a previous study showed how someone in a gorilla suit could walk through the middle of a busy basketball game without being spotted.
During the latest experiment, volunteers were asked to listen to separate conversations between two men and two women.
Dr Dalton and research associate Nick Fraenkel created a lifelike, three-dimensional auditory scene, containing one conversation between two men and another between two women.
Halfway through the recording they introduced a ‘gorilla man’, who walked through the scene repeating the phrase “I’m a gorilla!” for 19 seconds.
People who were concentrating on the men’s conversation were much better at detecting the ‘gorilla man’, however, most of those focused on the women's discussion failed to notice him.
The 'silent gorilla' experiment showed that sound, as well as visual information, can be subconsciously ignored if the brain is distracted.
Psychologist Polly Dalton, from Royal Holloway, University of London, said: "The 'invisible gorilla' effect, where people fail to see a person in a gorilla suit walking through a basketball game, is now quite well-known. Our study provides the first demonstration of a similar 'silent gorilla' effect in hearing.
"We were surprised to find such extreme effects with a listening task, because people often think of hearing as an 'early warning system' that can alert us to unexpected events that occur out of sight.
"The fact that a lack of attention can cause people to miss even distinctive and long-lasting sounds questions this view.
"This has real-world implications in suggesting, for example, that talking on your mobile phone is likely to reduce your awareness of traffic noises."
The life-like gorilla sound can be heard here - would this pull you out of your gossip concentration?
The research is reported in the journal Cognition.