BazermanMoore

After showing the video the first time, we ask our students whether anyone saw
anything unusual. In a large room, it is common for just a few people to mention seeing
a woman with an umbrella. When they offer this observation, the others in the room
scoff at it. Yet, when we show the video again to demonstrate what most of the class
missed, everyone sees the woman. By focusing on one task—in this case, counting
passes—people miss very obvious information in their visual world.
Using a video in which a person in a gorilla costume walks through a basketball
game, thumping his chest, and is clearly and comically visible for more than five seconds,
Simons and Chabris (1999) have replicated Neisser’s findings. Simons provides a
series of such demonstrations on a video that can be purchased at www.viscog.com.
We find the failure to see the obvious (including our own failure the first time we
saw the video) amazing because it violates common assumptions about our visual
awareness. This phenomenon has captured the interest of cognitive and perceptual psychologists,
and has become known as inattentional blindness (Simons & Levin, 2003).
Mack and Rock (1998) provide broader evidence in perceptual experiments that people
have a tendency not to see what they are not looking for, even when they are looking
directly at it. Mack (2003) points out that inattentional blindness might cause an airplane
pilot who is attending to his controls to overlook the presence of another airplane
in his runway. Similarly, many car accidents undoubtedly result from drivers focusing
on matters other than driving, such as talking on their cell phones (Levy, Pashler, &
Boer, 2006). We believe that research on inattentional blindness provides ample evidence
against the use of cell phones while driving, and even provides the evidentiary
basis for laws to prevent such use.
Recent work connects inattentional blindness to neural regions in the brain (Moore
& Egeth, 1997), and identifies many key independent variables that affect the probability
of not seeing the obvious (Mack, 2003). Beyond our own fascination with this basic research,
we are interested in making an analogy from this work in the visual realm to the
inattentional blindness that leads most decision makers to overlook a broad array of information
that is readily available in the environment. For instance, we are struck by the
many times our spouses have claimed to have told us something of which we have absolutely
no recollection. Like many people would, we tend to conclude that our spouses
must have imagined the interaction. But if we could miss seeing the woman with the
umbrella in Neisser’s video, we must accept the possibility that our spouses did indeed
provide the information that they claimed and that our minds were focused elsewhere.
CHANGE BLINDNESS
Change Blindness 47
Some of the most surprising studies of change blindness examine visual perception.
Change detection researchers have provided evidence that, in a surprisingly large number
of cases, people fail to notice visual changes in their physical environments
(Simons, 2000). For example, Simons, Chabris, Schnur, and Levin (2002) had an experimenter
who was holding a basketball stop a pedestrian and ask for directions. While
the pedestrian was giving directions, a group of people walked between the experimenter
and the pedestrian, and one member of the group surreptitiously took the basketball
from the experimenter. After the pedestrian finished providing directions, he or