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April 15, 2016
You’ve probably experienced something like this before: You’re knee-deep in a big project at work and are finally making some progress. You haven’t had to answer too many emails, the phone isn’t ringing off the hook, and you have just the right dosage of caffeine running through your system. You are in the zone, all your focus bent on finishing this assignment. Then you feel a tap on your shoulder. You jump, coming out of your trance, and spin around to see Fred from accounting standing behind you. He says, “Didn’t mean to startle you – I said your name a couple times but I guess you didn’t hear me.” Your hearing is perfectly fine, but he’s right, you didn’t hear him.
This phenomenon is common. People often “tune out” their surroundings when they are really concentrating on a task. This temporary deafness is so common, in fact, that few people really question its occurrence. Neuroscientists at University College London are among those few, and they recently conducted a study to pin down the science behind this phenomenon.
Previous studies have found that our brains can only focus on so many things at once.
Our attention is a limited resource and has to be divvyed up accordingly. If a task requires more brain power to complete, more attention is dedicated to that task. Easier tasks require less attention and therefore allow the rest of our attention to be focused elsewhere. This trend is demonstrated in studies of “inattentional blindness,” a phenomenon where people don’t see things that are irrelevant to the task at hand. For example, there is a classic inattentional blindness experiment that gives participants the task of watching a video of people playing basketball and counting the number of times they pass the ball to each other. At some point, someone dressed in a gorilla costume walks across screen. About half the time, participants dedicate so much attention to counting that they totally miss the gorilla.
This and other studies of inattentional blindness gave the University College London neuroscientists a starting point for their study on “tuning out.” “Tuning out,” they decided, could really be considered “inattentional deafness.” They wondered if dealing with a difficult visual task has the same affect on hearing as it has on sight. They designed an experiment to test how visual tasks of varying difficulty affected their participants’ ability to notice sounds. They recorded participants’ brain activity during the experiment using magnetoencephalography (MEG) technology. MEG monitors magnetic fields in the brain to see where electrical activity is being produced millisecond-by-millisecond.
The results showed that harder tasks did indeed make participants less likely to notice sounds. Certain areas of the brain light up when you become aware of a sound. These areas took longer to activate when participants were working on a tough visual task. In contrast, the activation in these areas during easier tasks was found to be quicker and stronger. The participants were also played sounds when they weren’t performing a task. During these trials, their brain responses to the sounds were not delayed at all.
These results suggest that inattentional deafness does work under the same mechanisms as inattentional blindness. When the brain is working on a difficult task, it draws attention away from other, easier tasks. To do this, it suppresses activity in the brain areas responsible for those easier tasks. In the same way that we try to reduce distractions when we need to get something done, the brain uses this method to complete difficult tasks more efficiently. The University College London study has shed new light on this process, demonstrating that hearing and sight share the same attention resources.
The University College London study brought us closer to understanding how our brains allocate our limited attention among different tasks. In understanding this, perhaps we can learn to work with our brains’ tendencies and train ourselves to focus more effectively. We live in an age of distractions – advertising, social media, cell phones, the Internet, and other technology constantly distract us from what we’re meant to be doing. By continuing to learn how our brains focus on different tasks, we can learn why these distracters sap our attention. Eventually, we can help children pay more attention at school and adults at work. In understanding why we tune things out, we can learn to do it on command.