Focused attention can make you oblivious to sights and sounds that would otherwise be glaringly obvious. This has been confirmed, with a great example being the “Invisible Gorilla” experiment, by psychologists Dan Simons of the University of Illinois and Chris Chabris of Union College, New York.
Guardian columnist Mocosandi writes:
Simons and Chabris investigated inattentional blindness in a real-world situation. They were inspired by the case of Kenneth Conley, a police officer in Boston who ran right past a vicious beating while chasing a suspect, and claimed not to have seen it. During his trial, the jurors assumed Conley must have been lying, and he was convicted of perjury and obstruction of justice.
Simons and Chabris simulated the scenario to test Conley's claim. They asked a group of participants to follow a jogger through a park, and staged a fight along the route. Some of the participants were also asked to watch the jogger closely and to count how many times he reached up and touched his hat.
Their findings were just as remarkable as those of the invisible gorilla experiment: at night, just one third of the participants said they had noticed the fight, while just over one half noticed it when the experiment was conducted during the day. Crucially, the researchers found that participants were far less likely to notice the fight when they were focusing their attention on how many times the jogger touched his hat.
Recent experiments have also lead to demonstration that focusing attention on a demanding visual task can lead to a failure to hear what would otherwise be an obvious sound.
These findings have obvious and important implications for everyday life. Texting on your mobile phone while crossing the road, for example, might deafen your ears to the sound of an approaching car. Similarly, focusing your attention on the sat nav or on a passing billboard might make you unaware of the sound of a car horn or cyclist's bell.
“The question of whether a certain sound or sight is noticed depends on the strength of the signal versus the level of ‘noise' around,” says Lavie. “If you put a glaringly obvious signal among lots of noise, people may still fail to notice it if their attention is occupied with a high information load. This suggests it is possible that if a car horn was played among other noises in conditions of high visual load … [it] would not be noticed either.”
Although inattentional blindness and deafness can often be unwanted consequences of focused attention, they also have their benefits. They can, for example, enable us to avoid distraction by ignoring irrelevant sights and sounds, such as pop-up ads or noisy building work near the office. “A lot of my research concerns these positive implications,” says Lavie, “which should be beneficial for learning and for greater productivity in the work place.”
If you want to learn more, try reading The Invisible Gorilla: How Our Intuitions Deceive Us.