We may think we’re pretty observant, but most of us suffer from what’s, in effect, a blind spot. It’s not an area of vision we can’t see — it’s just that we tend to miss changes in what we’re looking at and paying attention to. It’s called “change blindness,” and it’s just the way our minds work. The New York Times defined it as “the frequent inability of our visual system to detect alterations to something staring us straight in the face.” Psychologists have been trying to understand the phenomenon since the early 2000s. But, as the saying goes, the first step is realizing you have a problem.

Want to take a little visual quiz to see how change-blind you might be?

(LENSTORE.CO UK)

We’re going to assume you missed at least some of these. We sure did.

It seems like there’s hardly anything that’s too big for us to miss. Two experts, Michael Eysenck and Mark Keane, cite for verywell the jaw-dropping result of an experiment from the landmark 1998 study of change blindness done by Daniel J. Simons and Daniel T. Levin:

"For example, Simons and Levin (1998) carried out studies in which participants started to have a conversation with a stranger. This stranger was then replaced by a different stranger during a brief interruption (e.g., a large object coming between them). Many participants simply did not realize that their conversational partner had changed!"

(DANIEL LEVIN)

Yipes. So, what’s going on here? There are a few different theories, but they all come down to a simple fact: We have limited resources for paying visual attention. Jeremy Wolf told the Times, “The basic problem is that far more information lands on your eyes than you can possibly analyze and still end up with a reasonable sized brain.”

Simons suggests that since we lack the bandwidth to focus on everything, we pick and choose the things in view that matter, basically tuning out what goes on elsewhere. This is called “selective attention,” and numerous varieties of it have been proposed.

Another way of dealing with our limited attention capacity is to make assumptions based on prior experience, something than actually may be a more effective strategy in the real world than it is when looking at images in a test. In life, we don’t expect a mountain to disappear, so why would we bother to keep checking for such a thing, or for a person’s shirt color to change, for example? In addition, notes E. Bruce Goldstein, author of Sensation and Perception, when things change in life, we have reason to expect them to have more than one way to get our attention. He tells verywell, "One reason people think they would see the changes may be that they know from past experiences that changes that occur in real life are usually easy to see. But there is an important difference between changes that occur in real life and those that occur in change detection experiments. Changes that occur in real life are often accompanied by motion, which provides a cue that indicates a change is occurring."

eyes and collar

You probably notice the collar of the man’s shirt changing. What about her eye color? (DAVID SHANKBONE)

Other things may affect one’s level of change blindness, such as age, the manner in which objects are presented, and the presence of psychoactive drugs. One study by scientists at Queen Mary, University of London suggests that the changes we notice least are changes in colors. Of course, deliberately distracting a person also makes it more likely that something escapes their notice.

Or maybe it doesn’t, on an unconscious level. There is research that suggests we may be susceptible to being influenced by things we don’t know we’ve noticed. In experiments, eye tracking has revealed shifts to take in something subjects aren’t aware of looking at; when test subjects are asked to guess the location of a change they didn’t notice in a visual scene, they get it right at above-chance percentages. Interesting.

A person experiencing change blindness has no reason to think something’s wrong with them, though it can certainly have serious results if you’re driving, or, for example, hard at work as an air traffic controller — missing changing conditions in either case can be deadly. It’s also one reason eyewitness testimony in the courtroom is often unreliable, and it can cause you embarrassment when you mistake someone for someone else.

Beyond that, it’s a weird little gap in our mastery of our lives, reminding us just how cleverly — and yet, apparently fallibly — our brains apprehend complex reality. It does raise a question, though: Just how much are we missing?