New research has determined that inattentional blindness — the temporary obliviousness to extraneous stimuli during periods of intense focus — is much more common than most of us would like to think.

A new study from Brigham and Women's Hospital found that the condition is surprisingly prevalent even among highly trained experts, as 83 percent of the specialized subjects flunked the researchers' attention test.

The reason? None of them saw the gorilla.

"When engaged in a demanding task, attention can act like a set of blinders, making it possible for stimuli to pass, undetected, right in front of our eyes," said lead author Trafton Drew, Ph.D. "We found that even experts are vulnerable to this phenomenon."

In the experiment, researchers recruited 24 radiologists to perform a routine lung nodule detection task, a familiar professional activity that required them to examine five different pulmonary X-ray scans.

Each scan contained an average of 10 lung nodules. However, in the fifth scan, researchers added something that generally does not appear in X-rays: a gorilla.

The layered silhouette of a giant ape, 48 times larger than a lung nodule, appeared at the top corner of the scan. While eye-movement tracking measures indicated that most subjects stared right at it, a menacing 83 percent failed to register what they were actually looking at.

Believing themselves to be performing an isolated task, the radiologists would simply not allow their attention to wander, making it exceedingly difficult for any of them to process the ectopic primate.

"The radiologists missed the gorillas not because they could not see them, but because the way their brains had framed what they were doing. They were looking for cancer nodules, not gorillas," said Jeremy Wolfe, senior psychologist and director of the Visual Attention Laboratory at Brigham and Women's Hospital. "This study helps illustrate that what we become focused on becomes the center of our world, and it shapes what we can and cannot see."

Rather than a scathing indictment against the detection skills of today's radiologists, the new study is a simply a way of illuminating the prevalence and inevitability of the condition itself. Our mind, it seems, has a curious tendency to discriminate between relevant and irrelevant stimuli, and not even the most skilled experts are exempt from this phenomenon.

You'll find the researchers' results this week in Psychological Science. If you look for them, that is.

 

Source: Drew T, Võ ML-H, Wolfe JM. The Invisible Gorilla Strikes Again: Sustained Inattentional Blindness in Expert Observers. Psychological Science. 2013.