A psychologist and colleague of Kahneman’s who did not agree with his work on experts. Klein took the view that experienced professionals develop accurate intuitive skills—a view that was informed by his work with firefighters—in contrast with Kahneman’s view that experts were often overconfident in their abilities, which were in reality based mostly on luck. They published a joint paper asserting that there are different kinds of experts, and one can discern which types of experts have truly acquired the expertise they claim to have.