Change Blindness, The Magician
By Alexis Johannessen
Does your partner ever get upset with you for not noticing their haircut? Have you ever seen a magician make something appear out of thin air and wonder how that was possible? Or thought a car “came out of nowhere” when you were driving? We assume that wherever we look, we “see” everything that is happening in front of us, much like a camera. But this is not the case. In reality when we are trying to take everything in at once our senses are being overwhelmed by constant waves of stimuli, triggering an overload of sensations that are too much for the brain to process. This is a result of something called “Change blindness”.
How does change blindness affect everyday life?
We tend to hear the saying “seeing is believing” often, which represents how much trust we put in our visual perception to obtain information. However, research has shown that visual perception does not capture nearly as much of the world as we think. For example, a driver might believe that simply by looking around they would always be able to see an oncoming car, notice how close the bicyclist riding in the bike lane next to their car is, and see the child running out into the middle of the street to retrieve their ball. But they would be wrong. Even if the driver could view conditions without flaw, they could still miss any one of these events due to something else grabbing their attention—for example, if they were talking on a cell phone. Much of this concern is based on the existence of change blindness, “the inability to notice large changes that occur in clear view of an observer” (Rensink, 2005). This effect is extremely powerful and can be produced under many different conditions, especially when the changes are repeatedly made and the observer knows that they will occur.
How does attention relate to change blindness?
Believe it or not, but change blindness plays a large role in the effects created by magicians, in which objects suddenly appear, disappear, or are transformed in ways that seem to defy the laws of physics. But if you take a closer look you’ll see that many of these effects rely mainly on a manipulation of attention. Although there are many things going on during a performance, the audience is only able to focus on a few at one time. So the magician will draw your attention away from the trick to something else so you are unaware of the changes being made. In order to be aware of the changes being made visual attention is needed to see the change. Under normal conditions, the local motion signal created by a change automatically draws attention, allowing it to be seen. But if this signal is overwhelmed attention will no longer be automatically drawn to the change, allowing there to be change blindness.
How does change blindness relate to memory?
One of the most famous studies on change blindness was conducted by Daniel Simmons and Christopher Chabris in 1999. They had participants watch a video of people passing a ball and asked them to count the number of times the ball was passed. During the video, a woman in a gorilla costume walked right through the group of people passing the ball. When the video ended, the participants were asked to write down the number of passes. Then they were asked a series of follow-up questions including “did you see a gorilla walk across the screen”. 46% of participants had failed to notice the gorilla due to being preoccupied with the task of counting the passes. This demonstrated how change blindness can affect our memory. When our attention is focused on specific things we tend to ignore other stuff that is going on around us, and because of the lack of attention we won’t be able to accurately remember certain situations. In this study, many of the participants weren’t able to remember seeing a person in a gorilla costume walk right across the screen.
How do you avoid change blindness?
Reminding our selves to shift attention can help lower the negative effects of change blindness. But the most effective way to reduce change blindness is by simply knowing and understanding what it is. If you understand what change blindness is you can use this to become more self-aware of what you could possibly be missing due to your attention being elsewhere.
References
Chambers, C. (2016). Change blindness: can you spot the difference? The Guardian. https://www.theguardian.com/science/head-quarters/2016/sep/05/change-blindness-can-you-spot-the-difference
Durlach, P. (2004). Change blindness and its implications for complex monitoring and control systems design and operator training. Human-Computer Interaction. https://www.researchgate.net/publication/234791524_Change_Blindness_and_Its_Implications_for_Complex_Monitoring_and_Control_Systems_Design_and_Operator_Training
Kellison, I., McEvoy, S., Rizzo, M., Sparks, J., Vecera, S., & Viamonte, S. (2008). Change blindness, aging, and cognition. US National Library of Medicine National Institutes of Health. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146260/
Rensink, R. (2005). Change blindess. University of British Columbia. https://www2.psych.ubc.ca/~rensink/publications/download/RR-MGY.pdf
Smith, T. J., & Henderson, J. M. (2008). Edit blindness: the relationship between attention and global change blindness in dynamic scenes. Journal of Eye Movement Research. https://bop.unibe.ch/JEMR/article/view/2264/3460