Are you listening or hearing?

Have scientists solved why we zone out so listening fades into hearing and ignoring? 

We are all guilty of zoning out of conversations at some point or other. Remember when that flight attendant was giving the safety briefing that we really should have been paying attention to but, instead, we flicked open the in-flight magazine: something was being said in the background, but we had no idea what. Now new research, published in Cell Reports, has revealed why. There is, it suggested, significant differences in neuronal activity between listening and hearing.

"When you pay attention to a sound, you are listening; but when you don’t pay attention to it, you are just hearing," explains the study's author, Tania Rinaldi Barket from the University of Basal.

To investigate potential differences in the brain when either listening or hearing, mice were subjected to passive (hearing) and active (listening) phases whereby ‘meaning’ - in the form of a drop of soy milk - was applied to sounds in the listening phases. Neuronal activity was then recorded in several areas of their brains.

According to Barkat, "in the hearing phase, there was no benefit to paying attention to the sound, so the mice didn’t react to it."

The authors found that there were very specific but diverse responses in the brain depending on whether mice were in the active or passive phases of investigation. Some neurones became more active, others less active, some responded faster and others slower. Additionally, they found that neuronal changes upon applying attention occurred all over the brain rather than in a specific region.

"Really, it is attention that we are looking at. The next step is to understand the mechanisms behind these observations so that we can modify and influence them to help people or situations where attention is not as good as it could be," says Barkat. 

The research may also be relevant to the age-old problem suffered by the elderly, who often struggle with word discrimination and to differentiate between important and unimportant sounds. Barkat says that this may be down to more than the brain's reduced ability to process sounds, but also the ability to pay attention.

Drugs can be taken to improve the attention of those suffering from attention disorders such as ADD and ADHD and might therefore be of use, although Barkat points out that these drugs can also have unwanted side effects. Her team hope that this work will help to explain the pathways of attention more clearly so that we can find ways to activate these pathways without influencing other areas of the brain.