Why visual tasks make us temporarily ‘deaf’

London, Dec 10 (IANS) If you try to talk to someone who is focusing on a book or game and do not receive a response, they are not necessarily ignoring you, they might simply be not hearing you!

Concentrating attention on a visual task can render you momentarily ‘deaf’ to sounds at normal levels, a study finds, which suggests that the senses of hearing and vision share a limited neural resource.

“We found that when volunteers were performing the demanding visual task, they were unable to hear sounds that they would normally hear,” said study co-author Maria Chait from University College London (UCL).

Researchers examined brain scans of 13 volunteers to find that when they were engaged in a demanding visual task, the brain response to sound was significantly reduced.

“The brain scans showed that people were not only ignoring or filtering out the sounds, they were not actually hearing them in the first place,” Chait added.

Examination of people’s ability to detect sounds during the visual demanding task also showed a higher rate of failures to detect sounds, even though the sounds were clearly audible and people did detect them when the visual task was easy.

The phenomenon of ‘inattentional deafness’, where we fail to notice sounds when concentrating on other things, has more serious implications in situations such as the operating theatre, where a surgeon concentrating on their work might not hear the equipment beeping.A

Pedestrians engaging with their phone, for example texting while walking, are also prone to inattentional deafness.

The study was published in the Journal of Neuroscience.