‘Gorilla man’ goes unheard
Tracking a conversation can block out peripheral sounds
By Bruce Bower
SEATTLE — Good listeners inadvertently turn a deaf ear to unexpected sounds. Attending closely to a conversation creates a situation in which unusual, clearly audible background utterances frequently go totally unheard, says psychologist Polly Dalton of the University of London.
This finding takes the famous “invisible gorilla effect” from vision into the realm of hearing, Dalton reported November 4 at the annual meeting of the Psychonomic Society. More than a decade ago, researchers observed that about half of volunteers watching a videotape of people passing a basketball fail to see a gorilla-suited person walking through the group if the viewers are instructed to focus on counting how many times the ball gets passed (SN: 5/21/11, p. 16).
An ability to prioritize what sounds and sights to monitor supports daily activities, but it can also wipe out perceptions of obvious peripheral happenings. “We’re not aware of as much in the world as we think we are,” Dalton said.
Dalton and her colleagues created a 69-second recording of two men talking as they prepared food for a party and two women chatting as they wrapped a party gift. Headphones delivered one conversation to each ear of 41 volunteers, creating a sense of the four characters moving around a room as they talked. Partway into the recording, a man dubbed “gorilla man” by the researchers appears in the acoustic scene for 19 seconds saying “I’m a gorilla” over and over.