Human beings are very good at tuning things out – not noticing objects or events in that are in plain sight, or becoming indifferent to distracting sounds in their environment, such as the whirr of a fan. Psychologists and other scientists who have studied this tendency sometimes report startling and often amusing results. For example, the “Person Swap” where individuals approached by a stranger asking directions fail to notice when, after a momentary visual distraction, an entirely different stranger replaces the first inquirer.
And in the famous “Invisible Gorilla” experiment, observers who were asked to track the passing of a ball among players failed to notice an actor clad in a gorilla suit casually sauntering across the stage, even when the gorilla stopped to beat its chest.
As humorous as the experiments may be, this dulling of attention – referred to an “inattentional blindness” and “change blindness” — exists for a good reason. Quite simply, our brains could not handle the cognitive load of constantly having to attend to every sound, sight, and sensation in our environment. We need to be able to quickly and intuitively determine what is relevant, and filter out the irrelevant—without that, we’d never be able to complete tasks because our minds would constantly be bouncing from one distraction to another. Filtering out the irrelevant is what allows us to focus and sustain attention on whatever it is we are trying to do.
However, this very human tendency also can be dangerous. All manner of physical injuries occur simply when a person’s mind is unprepared to respond the unexpected. Thieves and pickpockets on crowded street often make off with their loot as unnoticed as they were unexpected. Potential assassins who look like ordinary spectators escape notice. Fortunately humans vary in their perceptual styles. Only about half of the ball-counters miss the gorilla; although those who do spot the gorilla may also be less accurate in reporting the number of ball passes. It’s just not that easy for our brains to multitask. But in the end, diversity of thought patterns helps everyone. You might not notice the unexpected hazard, but perhaps your partner will.