After a quick introduction by Peter Lepage, dean of the College of Arts and Sciences, Cornell professor of psychology Tom Gilovich began his Reunion Weekend lecture on "The Fallibility of Everyday Thinking," June 9, with a multiple choice question: What's the correct pronunciation of Lepage?

It could rhyme with badge, or with age. Perhaps it sounds like "le-PAHJ." Say you choose "le-padge." Then, what if a gnawing feeling sets in, telling you it is really "le-PAHJ?"

Do you keep your first answer, because first instincts are usually right? Or change the answer, because now you have given it more thought? You think back to advice from teachers and test-preparation manuals. You stick with your first answer.

Except: The advice was wrong. Answers based on gut instinct are actually no more likely to be right than changed answers, Gilovich said.

People believe in the first-instinct fallacy, he said, simply because having almost had the right answer hurts more than never having been close to it at all. And that leads people to believe it happens more than it actually does.

We hold false beliefs for all kinds of reasons, Gilovich said. But they usually come down to one of three basic principles.

First: People see too much order in random events. We think basketball players shoot in streaks, for example, yet studies repeatedly show that making one basket has no effect on the likelihood of making the next one. We suspect our iPods of duping us by picking favorites when we tell them to shuffle randomly. And we see images in things like clouds and smoke patterns, when none really exist.

Second: We seek out evidence that confirms the thing we are trying to test -- giving that evidence more weight than countering evidence. If we are looking for truth in the idea that people with cancer live longer if they are optimistic, for example, we look for optimistic cancer patients -- when it is just as vital, but not as intuitive, to find out how long pessimistic patients live.

And finally, we are "of two minds" about most things, Gilovich said -- tempted to make decisions based on what feels right rather than what we know empirically. It can feel right to buy a lottery ticket, for example; we can imagine ourselves winning, and thus we neglect the impossible odds.

Yet we still do make good decisions. The audience -- mostly alumni -- have all improved their critical thinking skills by being Cornellians, Gilovich said, and have learned to reason effectively and to engage problem-solving skills. Those who took psychology courses, he argued, are even better off. Psychologists, after all, are used to dealing with the messiest, most complex of systems -- people -- and to evaluating them without falling into common traps.

When Gilovich took questions from the audience, one was directed to Lepage: How does he pronounce his name?

The dean, who is also a professor of physics, thought for a moment, then shook his head.

"I'm sorry," he said. "I don't really know."