Inattentional Blindness

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Original URL: www.theregister.co.uk/2007/01/19/the_odd_body_seeing/

When is seeing not seeing?
By Dr Stephen Juan
Published Friday 19th January 2007 17:44 GMT

When is seeing not seeing?
Do you ever wonder how a magician is able to fool you with a trick, as they say, “right before your very eyes”?

Concentrate as much as you want, you cannot see the sleight of hand. Most of us believe that when we are looking at something, especially when we are really concentrating, we see everything important to see. But this is not true. And we have many behavioral studies to prove this.

As Dr. Daniel J. Simons, from the Department of Psychology at Harvard University writes in Trends in Cognitive Sciences (April, 2000), “Although we intuitively believe that salient or distinctive objects will capture our attention, surprisingly often they do not.

For example, drivers may fail to notice another car when trying to turn or a person may fail to see a friend in a cinema when looking for an empty seat, even if the friend is waving.” This behavioral phenomenon is called “inattentional blindness”. Some of the experiments with inattentional blindness have been fascinating:

When subjects are watching the movement of blue balls across the screen and trying to predict their direction, and then the balls suddenly change to green, 88 per cent of subjects fail to notice the color change.
When subjects are watching a video tape of two basketball teams passing the ball back and forth and then the uniforms of the one of the teams suddenly change color, one out of four subjects fails to notice the change.
When subjects are watching a video tape of a basketball game and a woman carrying an umbrella suddenly appears on the court amidst the players and the action and remains for as long as 4 seconds, again, one out of four subjects fails to notice her.
When subjects are viewing two crosses on a screen while trying to judge which is longer over several trials, and on the fourth trial one of the crosses suddenly becomes a rectangle, yet again, one out of four subjects fails to notice the change.
Some theories about inattentional blindness include:

Dr. S.B. Most and colleagues from the Department of Psychology at Harvard University write in Psychological Review (January 2005) that “the most influential factor” that affects how well one notices is “a person’s own attentional goals.”
So, as the theory goes, when you are watching a football game and vitally interested in the game’s outcome, you are less likely to notice the bikini clad girl standing on the sidelines holding a big sign in the shape of a heart.

Based on their experiments, Drs. Mika Koivisto and Antti Revonsuo from the Centre for Cognitive Neuroscience at the University of Turku in Finland theorize in Psychological Research (Epub July 2006) that the closer the change is to what we are already seeing the more we will notice the change.
It would seem that this is counter-intuitive and it would be just the opposite. But presto! There it is. That’s what subjects reveal. Unlike magicians, nothing up their sleeve!

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to [e-mail] (mailto:[e-mail])