The researchers recruited 24 radiologists from the hospital and asked them to go through the CT scans of five patients who took a lung cancer screening test.
While the images of the first four patients were clean, five consecutive images from the 239 images of the CT scan of the fifth patient contained a dancing gorilla with varying degree of transparency.
The researchers tracked the eye movements of the radiologists and found that though the radiologists looked right at the gorilla on a average of four times, just four of the 24 radiologists said that they were able to identify the gorilla. "The majority of them looked directly at the gorilla for extended periods of time. They just don't see it", lead researcher Trafton Drew said.