Why Change Blindness Happens

If something in your visual field were to change dramatically before your eyes, you would notice it immediately, right? Not necessarily. Your surroundings simply offer too much information for your brain to fully process, so you might miss even large changes. This phenomenon is known as change blindness. Here's why change blindness happens.

Research on Change Blindness

The idea of change blindness isn't new; in fact, researchers have studied it for decades. The ability to detect change plays an important role in daily life—helping you notice when a car drifts into your lane or a person enters a room. Many fascinating experiments have explored aspects of this phenomenon, such as:

• How changing the direction of a stimulus induces change blindness, which might explain how many magic tricks work.
• Whether people noticed—or did not notice—changes in type, distance, complexity, and field of view in an immersive environment. They found that people with good working memories were more apt to notice them than were their more forgetful counterparts.
• How strength and stability of a stimulus can help you perceive change
• Whether a brief break between one version of an image and another would make changes more difficult to detect.
• Whether participants would notice that their conversation partners had been swapped out for others after a period of distraction.

Causes of Change Blindness

If the ability to perceive change is so important, why do humans often fail to notice even major ones? Researchers have a few ideas.

Focused Attention and Limited Resources

At this moment, your attention is focused on the words you are reading. Are you giving any attention to the color of the nearby wall? Are you aware of the position of your feet? Until now, you probably weren't paying attention to either of those things.

According to researchers Daniel Simons and Daniel Levin, that's because your limited capacity for attention forces you to choose what to focus on. Lots of information simply passes us by because we lack the resources to attend to it.

Expectations and Experiences

Certain changes—particularly those that are artificially produced in an experimental lab—tend to go unnoticed because they're unexpected. How often does a person suddenly turn into someone else, an object suddenly blink into existence, or a person's shirt change color? These things simply don't happen, so they're typically overlooked when they're staged for an experiment.

Other Factors

Other factors that can influence change blindness include attention, age, presentation, and the use of psychoactive drugs. Researchers have also found that distraction increases change blindness.

Age can also play a role: studies have found that older people are less likely to detect changes in a visual scene than younger people. Again, the ability to take in visual information is constrained by limited resources.

To cope with an overwhelming amount of data, you focus on a single part of the environment that you deem important enough to process.

Change Blindness in the Real World

Change blindness might cause problems in real-world situations, such as:

• Air Traffic Control. A disaster could result if an air traffic controller failed to detect changes when monitoring takeoffs, landings, and flight paths.
• Driving. Failure to detect changes in the environment while you are driving can lead to dire consequences. Distractions such as talking on the phone or texting while you drive can decrease attention and increase change blindness.
• Eyewitness Testimony. Change blindness can affect an eyewitness's ability to recount the details of a crime or to correctly identify the perpetrator.
• Social Interactions. Change blindness can affect day-to-day social interactions—for example, asking the wrong waiter for the check when you're dining out.

A Word From Verywell

Humans rely on their ability to detect change. Yet the human brain sometimes lacks sufficient resources to focus on all the details when so much information floods it at any given moment. So, it directs attention to the most important stimuli and lets the rest go. The result: Change blindness.