Dealing with demanding visuals can leave us temporarily deaf
It’s amazing we ever thought we were multitaskers. Sure, we can keep our hearts, digestion and respiration going at once, but parsing multiple streams of sensory input seems to be too tall an order. This isn’t to say that we’re bad at observing the world— our eyes and visual cortex do an amazing job of building a rich, detailed view of the world. It’s just that our focus, our attention, can only go so far. Researchers have now demonstrated that its possible to overburden our concentration in a way that may seem obvious, only because it happens so frequently. If my grammar gets too complicated or muddled, it might even happen to you right now.
One input at a time
It seems that when we’re concentrating on a visual task, that concentration comes at the cost of our hearing. And vice versa- listening intently makes us start to miss visual information. This so called “inattentional deafness” can obviously be of great concern, since that may mean that staring at a text on your phone could prevent you from hearing a truck honking at you. It also helps explain why it’s sometimes so hard to read and listen to someone at the same time. You don’t have the attention for both, and so your brain has to pick one or the other. These examples are probably very familiar, but the new studies shed light on just how involuntary and extreme this input selection really is.
Study participants were asked to do visually oriented tasks with varying degrees of difficulty. The most taxing task was to judge the color and relative lengths of lines in a cross shape. At the same, test subjects would either listen to silence, white noise, or white noise with a occaisonal tones played over it. As the visual task became more difficult, demanding more concentration, the participants were less and less likely to notice the tones being played. With enough of a visual challenge, they just wouldn’t hear the tone at all. Variations on these tests were repeated to make hone in on the critical components- did the white noise play a role? Did it matter if color was being judged in the visual task? In the end, the pattern turned out to be that the harder the brain worked on visuals, the more it tuned out audio information.
Brain scans found that this self-imposed silence wasn’t just a case of filtering or ignoring unwanted stimuli- the brain basically discarded the sounds almost from the get go. Sound was obviously picked up by the person’s ears, but before that signal was dropped before it made it to the frontal cortex to really be considered or parsed by the brain. Aside from legitimizing when people say they didn’t hear someone speaking to them, it shows that this process is beyond individual will or choice, and that safety systems need to be designed with this temporary, self-imposed deafness in mind.
Source: We Exhibit ‘Inattentional Deafness’ To Sound While Focusing On Visual Tasks: Your Friend Looking At His Phone Isn't Quite Ignoring You by Ali Venosa, Medical Daily