black face; different evidence had been emphasized. The stakes of prejudice can be high, as in the following example from the New York Times.
“JERUSALEM, Jan. 4 -- A bus driven by an Arab collided with a car and killed an Israeli woman today, and the bus driver was then shot dead by an Israeli near the Gaza Strip.
“Palestinians and Israelis gave entirely different versions of the episode, agreeing only that the bus driver, Mohammed Samir al-Katamani, a 30-year-old Palestinian from Gaza, was returning from Ashkelon in a bus without passengers at about 7 A.M. after taking families of Palestinian prisoners to visit them in jail.
“The bus company spokesman, Mohammed Abu Ramadan, said the driver had accidentally hit the car in which the woman died. He said the driver became frightened after Israelis surrounded the bus and that he had grabbed a metal bar to defend himself.
“But Moshe Caspi, the police commander of the Lachish region, where the events took place, said the driver had deliberately rammed his bus into several cars and had been shot to death by a driver of one of those vehicles.
“The Israeli radio account of the incident said the driver left the bus shouting ‘God is great!’ in Arabic and holding a metal bar in his hand as he tried to attack other cars.” [Ibrahim, 1991]
***
“What a man sees depends both upon what he looks at and also upon what his previous visual-conceptual experience has taught him to see.” [Kuhn, 1970]
The emotional relationship between expectation and perception was investigated in an elegantly simple and enlightening experiment by Bruner and Postman [1949]. They flashed images of playing cards in front of a subject, and the subject was asked to identify the cards. Each card was flashed several times at progressively longer exposures. Some cards were normal, but some were bizarre (e.g., a red two of spades).
Subjects routinely identified each card after a brief exposure, but they failed to notice the anomaly. For example, a red two of spades might be identified as a two of spades or a two of hearts. As subjects were exposed more blatantly to the anomaly in longer exposures, they began to realize that something was wrong but they still had trouble pinpointing the problem. With progressively longer exposures, the anomalous cards eventually were identified correctly by most subjects. Yet nearly always this period between recognition of anomaly and identification of anomaly was accompanied by confusion, hesitation, and distress. Kuhn [1970] cited a personal communication from author Postman that even he was uncomfortable looking at the bizarre cards. Some subjects never were able to identify what was wrong with the cards.
The confusion, distress, and near panic of attempting to deal with observations inconsistent with expectations was eloquently expressed by one subject:
“I can’t make the suit out, whatever it is. It didn’t even look like a card that time. I don’t know what color it is now or whether it’s a spade or a heart. I’m not even sure now what a spade looks like. My God!”
***
Let us now consider a critical aspect of the relationship between expectation and perception: how that relationship is reinforced. Lord et al. [1979] investigated the evolution of belief in an hypothesis. They first asked their subjects to rate how strongly they felt about capital punishment. Then they gave each subject two essays to read: one essay argued in favor of capital punishment
