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What Is Change Blindness?

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What Is Change Blindness?

Change blindness happens when we fail to notice changes in our environment.

Image: John O'Neill / WikiCantona (CC BY-SA 3.0)

Question: What Is Change Blindness?

If something in your visual field changed dramatically right before your eyes, you would notice it immediately, right? While you might think that you see or are aware of all the changes that happen in front of you, the reality is that there is simply too much information for your brain to fully process and be aware of every single thing that happens in your immediate environment.

In many cases, big shifts can happen in your visual field and you are never even aware of these changes. Psychologists refer to this as change blindness.

What is it? Why exactly does it happen? What effect does it have on how you perceive and interact with the world around you?

Let's start by answering the basic question: What is change blindness?

Answer:

Defining Change Blindness

  • "The term 'change blindness' refers to the surprising difficulty observers have in noticing large changes to visual scenes."
    (Simons & Rensink, 2005)

  • "Change blindness is a failure to detect that an object has moved or disappeared and is the opposite of change detection. The phenomenon of change blindness can be demonstrated even when the change in question is large. 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!"
    (Eysenck & Keane, 2005)

Research on Change Blindness

  • Blackmore, Belstaff, Nelson, and Troscianko (1995) - In this experiment, participants were shown an image that was changed during a brief blank interval in the visual scene. The researchers found that when there is a brief break in the visual scene, people find it more difficult to detect changes.

  • Simons and Levin (1998) - In this experiment, researchers engaged participants in a conversation. Then, during a period of distraction, they switched the original person for someone else. Surprisingly, only about half of the participants noticed the swap.

  • O’Regan, Rensink, & Clarke (1999) - Researchers found that when small shapes are splattered over an image, such as mudsplashes over a car windshield, large changes can be made to a visual scene without the observer noticing. While previous research demonstrated that change blindness could be produced by a visual disruption such as flickering, blinking, or eye movement, this study demonstrated that change blindness can also occur without visual masking.

  • Levin et al. (2000) – When researchers told observers about changes that happened in a film sequence and showed them stills from the film, 83 percent of the participants predicted that they would notice these changes. When these observers did not know which changes were going to occur, only 11 percent of them actually noticed the changes.

  • Feil & Mestre (2010) - Recent research also suggests that subject-matter experts may be more adept at noticing change in their area of expertise than novices. For example, a physicist would be better able to detect changes to a physics problem than a college student taking his first physics course.

Why Does Change Blindness Occur?

The ability to detect change plays a major role in our daily life. A couple of examples include noticing when a car drifts into our lane of traffic or observing a person entering a room. If perceiving change is so important, why do we often fail to notice major changes?

There are a number of factors that play a role:

Focused Attention and Limited Resources

At this very moment, your attention is focused on the words you are reading. While you are looking this sentence, are you giving any attention to the wall color of the room you are in or to where your feet are placed? Until I asked you that question, it's highly unlikely that you were paying attention to either of those things.

According to researcher Daniel Simons, attention is limited, so we have to pick and choose what we focus on. We can really only focus on one thing at any given time, so it is that one thing that we pay attention to in great detail. As a result, large volumes of information in the world around us simply pass by our awareness because we lack the resources to attend to it.

What are some other possible explanations for change blindness?

Expectations and Past Experiences

"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." (Goldstein, Sensation and Perception, 2010)

We don't notice some changes, particularly the artificially induced ones in an experimental lab, because we simply don't expect such changes to occur. How often in real life does one person suddenly turn into somebody else? When would an object suddenly blink into existence when it wasn't there before? Would a person's shirt really change color right before our eyes? Because these things simply don't occur in our day to day existence, we tend not to notice them when they happen in an staged experiment or scene.

Other Factors That Play a Role

A number of factors can also influence change blindness, including attention, age, how objects are presented, and the use of psychoactive drugs. Researchers have found that shifting a person's attention, such as causing a distraction, leads to increased change blindness. Studies have found that older people are less likely to detect changes in a visual scene.

Our ability to take in visual information is constrained by limited resources. "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," explained researcher Jeremy Wolfe of Harvard Medical School to The New York Times. To cope with this overwhelming amount of data, huge amounts of information enter our visual system without being assimilated. Focused attention on a particular part of our environment allows us to essentially shine a spotlight on something that we deem as important that needs to be processed and attended to.

Change Blindness in the Real World

Detecting change plays a major role in our ability to function in our daily life. You can probably already think of a few examples of when change blindness might cause problems in real-world situations.

Some of these include:

  • Social Interactions: Change blindness can impact our day-to-day social interactions such as relatively minor slip ups like asking the wrong waiter for the check

  • Driving: Failure to detect changes in the environment while you are driving can lead to dire, sometimes fatal, consequences. Researchers have found that distractions such as talking on the phone or texting can impact attention and lead to increased change blindness.

  • Eyewitness Testimony: Researchers have found that change blindness can also play a role in a witnesses ability to recount the details of a crime or to identify the perpetrator of a crime.

  • Air Traffic Control: If an air traffic control fails to detect important changes, fatal accidents could result.

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References

Angier, N. (2008, April 1). Blind to change, even as it stares us in the face. The New York Times. Retrieved from http://www.nytimes.com/2008/04/01/science/01angi.html

Davies G, Hine S.(2007). Change blindness and eyewitness testimony. The Journal of Psychology 141(4), 423-434.

Eysenck, M. W. & Keane, M. T. (2005). Cognitive psychology: A student's handbook. New York: Psychology Press Ltd.

Goldstein, E. B. (2010). Sensation and perception. Belmont, CA: Wadsworth.

O'Regan, J. K., Rensink, R. A., & Clark, J. L. (1999) Change-blindness as a result of “mudsplashes”. Nature. doi:10.1038/17953

Simons, D. J. & Rensink, R. A. (2005) Change blindness: Past, present, and future. Trends in Cognitive Sciences, 9(1), 16-20.

 

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