Here's proof that you aren't just ignoring your spouse: A new study out of University College London finds you can become temporarily deaf when focusing on a visual task, like reading a book, watching TV, or perusing your smartphone, reports Tech Times. "In order to hear, we don't just need our ears to be operating; we need our brain to respond to the sound," author Nilli Lavie explains. In the Journal of Neuroscience, Lavie and her team note a person's sense of vision and hearing are found in the same region of the brain called the association cortex. Here, capacity is limited, so rather than multi-task, your brain chooses whether to see or hear at a given time. Previous research shows people lose focus on what's in front of them when listening to sounds, reports Discovery News. When vision takes priority, there is "inattentional deafness," researchers say.
To reach that conclusion, they asked 13 people to press a key when a certain letter appeared on a computer screen while listening to music. After conducting brain scans, researchers found participants could detect sounds when the visual task was easy. But when it became more demanding, the brain's response was significantly lower. "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," a researcher says in a release. While this might seem harmless, it can be dangerous for drivers focusing on directions or pedestrians who are texting. A focused surgeon might also fail to hear the beeping of equipment. As for other effects: "You may think that the person is ignoring you, but their brain just can't respond to your voice," says Lavie. "You shouldn't take it personally." (Up to 20% of people may "hate sound.")