Read How We Know What Isn't So for Free Online Page A

and “aggressive” looking. These perceptions influence, in turn, how specific actions performed by black-uniformed teams are viewed. We showed groups of trained referees one of two videotapes of the same aggressive play in a football scrimmage, one with the aggressive team wearing white and one with it wearing black. The referees who saw the black-uniformed version rated the play as much more aggressive and more deserving of a penalty than those who saw the white-uniformed version. The referees “saw” what this common negative association led them to expect to see. As a result of this bias, it is not surprising to learn that teams that wear black uniforms in these two sports have been penalized significantly more than average during the last two decades. 5
    Unambiguous Information.
Our expectations can also slant our evaluations of unambiguous information, but in a rather different manner. In evaluating more clear-cut information, our perceptions are rarely so distorted that information that completely contradicts our expectations is seen as supportive. Nor do we simply ignore contradictory information and pay attention only to that which supports our preconceptions. Rather, our expectations have their effects through the way we subject inconsistent information to more critical scrutiny than consistent information; through the way we seek out additional information only when the initial outcomes are inconsistent with our expectations; and—more generally—through the way we assign meaning to new information. People place a premium on being rational and cognitively consistent, and so they are reluctant to simply disregard pertinent evidence in order to see what they expect to see and believe what they expect to believe. Instead, people subtly and carefully “massage” the evidence to make it consistent with their expectations. (A similar argument is made in Chapter 5 about the biasing effects of our motivations ).
    This point is effectively illustrated by a study in which proponents and opponents of the death penalty were exposed to evidence concerning the deterrent efficacy of capital punishment. 6 Both groups read summaries of the procedures, results, and critiques of two relevant studies. One study provided evidence supporting the deterrent efficacy of capital punishment and the other provided evidence against. For half the participants, the study supporting capital punishment compared homicide rates in the same state before and after capital punishment, and the study refuting its deterrent efficacy compared homicide rates in different states, some with capital punishment and others without. For the other participants, the type of studies supporting and refuting capital punishment was reversed. Thus, for both proponents and opponents of capital punishment, half of them had their expectations supported by one type of study and opposed by the other, and the other half were exposed to the opposite pattern of data.
    The results of this experiment were striking. The participants considered the study that provided evidence consistent with their prior beliefs—regardless of what type of study that was—to be a well-conducted piece of research that provided important evidence concerning the effectiveness of capital punishment. In contrast, they uncovered numerous flaws in the research that contradicted their initial beliefs. The net effect of these two results was that the participants’ attitudes became polarized: Exposure to a mixed body of evidence made both sides even more convinced of the fundamental soundness of their original beliefs.
    Now consider what the participants in this experiment did
not
do. They did not miscontrue the evidence against their position as being more favorable than it really was. They correctly saw hostile findings as hostile findings. Nor did the participants simply ignore these negative results. Instead, they carefully scrutinized the studies that produced these unwanted and unexpected