ExposureBlog

Since many cases are won or lost on the testimony of eyewitnesses, a recent study cited here should raise some eyebrows.  It concerns the psychological phenomenon known as inattentional blindness, or the inability of some normal individuals  to recognize something when their attention is directed elsewhere.  The phenomenon is well-known in psychology. Visual expert Marc Green has a good article on inattentional blindness and human error,  and there is a book on the subject by Australian researchers Arien Mack and Irvin Rock.

I have read depositions in which the deponent is asked over and over whether he or she saw something take place.  If the response is in the negative the assumption is that the event did not, in fact, occur—or that those who say that it did are not telling the truth.  Well, not so fast.

In the study, conducted by Dr. Seema L. Clifasefi of the University of Washington at Seattle, 47 participants were asked to watch a basketball game and count the number of times a basketball was passed back and forth between teams.  Some were given an alcoholic beverage and others were given an alcohol-free beverage.  During the game, a woman in a gorilla suit appeared on the screen, stood amidst the players, beat her chest and walked away.  When questioned later whether they had seen the gorilla, fully a third of the participants had NOT noticed the gorilla.  Of those not consuming alcohol, only 46% recalled seeing the gorilla.  Of those consuming alcohol, only 18% recalled the gorilla.

It would seem, then that if an eyewitness was engaged in behavior that required his full attention, the odds of noticing details of a specific incident may be less than 50 percent.