The Undoing Project: A Friendship that Changed the World(35)
After the war Avi, by then twenty-two years old, finally decided what he would study: psychology. Had you asked him just then why he picked psychology, “I would say I want to understand the human soul. Not the mind. The soul.” Hebrew University had no room for him, so he went to a new university south of Tel Aviv called the University of the Negev. The campus was in Beersheba. He took two classes from a professor named Danny Kahneman, who was moonlighting because his job at Hebrew University didn’t pay enough. The first was an introduction to statistics, which sounded deadly, only it wasn’t. “He made it real by taking all these examples from life,” recalled Avi. “He wasn’t just teaching statistics. He was teaching: what is the meaning of all this?”
Danny was then helping the Israeli Air Force to train fighter pilots. He’d noticed that the instructors believed that, in teaching men to fly jets, criticism was more useful than praise. They’d explained to Danny that he only needed to see what happened after they praised a pilot for having performed especially well, or criticized him for performing especially badly. The pilot who was praised always performed worse the next time out, and the pilot who was criticized always performed better. Danny watched for a bit and then explained to them what was actually going on: The pilot who was praised because he had flown exceptionally well, like the pilot who was chastised after he had flown exceptionally badly, simply were regressing to the mean. They’d have tended to perform better (or worse) even if the teacher had said nothing at all. An illusion of the mind tricked teachers—and probably many others—into thinking that their words were less effective when they gave pleasure than when they gave pain. Statistics wasn’t just boring numbers; it contained ideas that allowed you to glimpse deep truths about human life. “Because we tend to reward others when they do well and punish them when they do badly, and because there is regression to the mean,” Danny later wrote, “it is part of the human condition that we are statistically punished for rewarding others and rewarded for punishing them.”
The other class Danny taught was about perception: how the senses interpreted and, occasionally, misled. “Let me tell you: After two classes it was clear that this guy was brilliant,” said Avi. Danny recited long passages from the Talmud in which the rabbis described day turning to night, and night turning to day, then asked the class: What colors are these rabbis seeing at that moment, when day turns to night? What did psychology have to say about the way the rabbis saw the world around them? Then he told them about the Purkinje effect—named for the Czech physiologist who had first described it, in the early nineteenth century. Purkinje had noticed that colors that appeared brightest to the human eye in broad daylight appeared the darkest at dusk. And so, for instance, what the rabbis saw as vividly red in the morning might appear, in contrast to other colors, almost colorless in the evening. Danny seemed to have in his head not only every strange phenomenon ever uncovered by anyone but an ability to describe them all in ways that led a student to see the world just a bit differently. “And he came to class with nothing!” said Avi. “He just came in and started talking.”
A part of Avi couldn’t quite believe the spontaneity of Danny’s performances. He wondered if perhaps Danny had memorized his lectures and was just showing off.” That suspicion was dispelled the day that Danny arrived to class and asked for help. “He came to me,” recalled Avi, “and he said, ‘Avi, my students at Hebrew University want me to give them something in writing, and I don’t have anything. I saw you writing notes. Can I have them so I have something to give them?’ . . . Everything was in his head!”
Avi soon learned that Danny expected his students to stuff their minds in much the same way that he had. Toward the end of his class on perception, Avi was called to army reserve duty. He went to Danny to say that, sadly, he needed to leave to patrol some remote border, and so he didn’t see how he could keep up with the work and had to drop out of the class. “Danny said to me, ‘It’s okay, just learn the books.’ And I said, ‘What do you mean, just learn the books?’ And he said, ‘Take the books with you and memorize them.’” And so that’s what Avi had done. He returned to Danny’s classroom just in time for the final exam. He’d memorized the books. Before Danny handed back the exams to the students, he asked Avi to raise his hand. “I raised my hand—what did I do this time? Danny says, ‘You got 100 percent. And if someone gets a grade like this it should be said publicly.’”
After studying with this moonlighting professor from Hebrew University, Avi made two decisions: He would himself become a psychologist. And he would study at Hebrew University. He assumed that Hebrew University must be a magical place where the professors were geniuses who inspired their students to new heights of passion for their subjects. And so for graduate school Avi went to Hebrew University. At the end of his first year, the head of Hebrew University’s Department of Psychology, surveying students, pulled Avi aside. How are your teachers? he asked.
They’re okay, said Avi.
Okay? said the department head. Just okay? Why are they only okay?
I had this one teacher in Beersheba . . . , Avi started to say.
The department head immediately sensed what had happened. Oh, he said, You’re comparing them to Danny Kahneman. You can’t do that. It’s not fair to them. There’s a category of teacher called Kahnemans. You cannot compare teachers to Kahnemans. You can say this guy is bad or good compared to others. That’s okay. But not to Kahneman.