Visual Paradox

It was interesting to find the following information about vision in The Beautiful Cure: The Revolution in Immunology and What it Means for Your Health by Daniel M. Davis. In trying to understand more about the immune system and how it makes an appropriate level of response, the immunologist Ralph Steinman discovered accessory cells by looking at cells from the spleen which stuck to glass, cells with a unique appearance and movement from within a hodgepodge of cells. This was not only an exceptional act of science but also an exceptional act of perception.

 A scientific discovery such as this, made by just watching cells down a microscope, doesn’t happen as simply as might be imagined. One of the reasons it is so difficult has been strikingly illustrated by two Harvard psychologists, Christopher Chabris and Daniel Simons, who asked volunteers to watch a video of six basketball players – three in white T-shirts and three in black – walking around and passing basketballs between them. Chabris and Simons asked the viewers to count the number of times a basketball is passed between two players both wearing white T-shirts, which takes a bit of concentration. Halfway through the video, which you can watch for yourself online, a woman in a gorilla costume walks onto the scene, stands among the players, beats her chest facing the camera, and walks off. Afterwards, the viewers are asked if they noticed anything unusual. Despite the fact that eye-tracking equipment showed that all the viewers had gazed straight at the gorilla for an equivalent length of time, only half had noticed her. This ‘perceptual blindness’ was even worse when tested on a group of expert radiologists, who were asked to look through computed tomography (CT) scans of lungs in search of nodules, which would appear as bright white circles. While some of the scans also showed pictures of a gorilla that was forty-eight times larger than the nodules the experts were told – and trained – to look for, 83% of the radiologists missed seeing the gorilla despite gazing right at her.

These experiments emphasize an important truth: we see with our brains rather than with our eyes. Our brains filter and interpret everything detected by our body’s sensory organs and because of this, we often see only what we are looking for and fail to notice the unexpected.  


When vision is enhanced or re-mediated, most of the changes take place in the brain. The effects of vision therapy cannot be understood without realizing this.

For More:

Reading as a Perceptual Skill

Visual Perception and Who We Are

Stress and Mindset