Pathologists and clinical laboratory managers should be aware of the possibility of ‘inattentional blindness’ as a potential cause for diagnostic and laboratory error
Pathologists and clinical laboratory professionals who regularly analyze images will be interested in the findings of a research study designed to assess how the phenomenon called “inattentional blindness” among radiologists could cause them to possibly miss things hiding in plain sight.
‘Inattentional Blindness’ Occurs Even Among Highly-trained Radiologists
In a recent study, psychological scientists from Harvard’s Brigham and Women’s Hospital found that 83% of radiologists didn’t notice an image of a gorilla embedded in a computed tomography (CT) lung scan.
“If you watch radiologists do what they do, [you’re] absolutely convinced that they are…superhuman,” observed Drew.
However, even radiologists can fail to perceive an abnormality, reported a story published on the American Journal of Roentgenology (AJR) website. That’s true even when the abnormality is apparent in retrospect.
According to AJR, these errors are of two types:
- cognitive errors, in which an abnormality is seen but its nature is misinterpreted; or,
- perceptual “misses,” in which a radiologic abnormality is simply not seen by the radiologist on initial interpretation.
Perceptual errors account for about 80% of all radiologic errors, the AJR author wrote.
The Invisible Gorilla Study by Researchers at Harvard Medical School
Perceptual blindness, or inattentional blindness, is the failure to notice an unexpected stimulus that is in one’s field of vision, according to Wikipedia. It occurs when other tasks are being performed which also demand attention. It is not associated with any defect in vision. Instead, it is categorized as an error of attention.
About three years ago, Drew began visiting radiology “reading rooms” to observe how radiologists work. He wanted to determine whether individuals highly trained in searching CT scans for abnormalities would pick up a “gorilla in their midst.”
“You might expect that because they’re experts, they would notice if something unusual was there,” stated Drew.
In 2004, Harvard psychologists Christopher Chabris, Ph.D., and Daniel Simons, Ph.D., received the Ig Nobel Prize in Psychology for their research. It included what is known as the “invisible gorilla study.”
In the study, subjects were shown a video of two teams moving around and passing basketballs to one another. The subjects were asked to count the number of passes made by players wearing white shirts. Halfway through the video, someone in a full gorilla costume walks to the center of the scene, stops and beats on her chest, then continues walking out of the group. Impossible to miss? Approximately 50% of the subjects failed to notice the gorilla.
By selecting the link above, you can see the original and now world-famous awareness test from Daniel Simons, Ph.D., and Christopher Chabris, Ph.D., in the form of a video first filmed in 1997. (Video copyright Simons and Chabris)
Subjects were shown a video of two teams moving around and passing basketballs to one another. The subjects were asked to count the number of passes made by players wearing white shirts. Halfway through the video, someone in a full gorilla costume walks to the center of the scene, stops and beats on her chest, then continues walking out of the group. Impossible to miss? Approximately 50% of the subjects failed to notice the gorilla.
Education and Training Have Little Effect on Perceptual Blindness
Drew and Wolfe recruited 24 experienced and credentialed radiologists, reported a story published at gismodo.com. They also recruited a comparable group of naive volunteers. They found that 83% of the radiologists failed to see the gorilla embedded in the lung scan.
For professional “searchers,” such as radiologists or pathologists, the brain frames the search of a film or slide according to the context of what is expected. For example, the radiologists in the study were looking for cancer nodules, not gorillas. Therefore, they had unconsciously filtered out dissimilar data—including an angry-looking gorilla shaking its fist!
“They look right at it, but because they’re not looking for a gorilla, they don’t see that it’s a gorilla,” stated Drew.
It is difficult to reduce risk of attentional blindness, according to the National Institutes of Health website post. When a person is asked to perform a challenging task, their attention narrows and their mind blocks out other things.
What we are focused on filters the world around us very aggressively, Drew explained. This filtering process literally shapes what we see. According to Drew, that means we need to think carefully about the instructions we give to professional searchers like radiologists—or pathologists.
Drew and Wolfe are doing further studies for possible ways to help radiologists see both visually and cognitively the things that sometimes are hiding in plain sight.
For pathologists and clinical laboratory managers, awareness of inattentional blindness may be one step in the direction of finding ways to reduce possible errors and improve the quality and accuracy of diagnoses.
—Pamela Scherer McLeod