Confidence is indisputably a good thing. But over-confidence can spell trouble—especially when we're learning. Research has shown over and over again that we are not very good judges of how effectively we're learning new information, or how accurately we'll remember it. This means we may stop the studying or training process prematurely, before new material is truly absorbed, and it means we may be in for an unpleasant surprise when we realize (at test or performance time) that we didn't know that material as well as we assumed.

This overconfidence shows up in all kinds of settings: among debate teams taking part in a college tournament; among hunters quizzed about their knowledge of firearms just before the start of hunting season; and among medical residents evaluating their patient-interviewing skills, to cite a few examples collected by Cornell University psychologist David Dunning in a study published in the journal Current Directions in Psychological Science. In that study, Dunning and his coauthors found that the lowest-performing students in a college psychology course overestimated their own performance by an average of 30 percent.

How can you avoid overconfidence, and achieve an accurate sense of how well you're learning? Try these four tips.

Wait a while. We often base our judgments of how well we're learning on how easily we can call the learned information to memory. This cue may be misleading, however, if we retrieve the material while it's still fresh in our minds. Hold off a day or two, or even just a few hours, and then check how well you know it. Psychology professor Bennett L. Schwartz reports that "testing oneself—not immediately after studying, but after a meaningful delay—greatly increases the accuracy of JOLs." (JOLs is psychologist-speak for "judgments of learning.")

Put notes and books away. Another cue we use to assess how well we've learned new information is its "ease of processing"—how easy it seems to understand and remember in the first place. One habit many of us fall into is checking our preparedness by "looking over" notes or textbooks. But a study led by Purdue University professor Jeffrey Karpicke finds that such re-reading breeds overconfidence: "When students have material right in front of them, as they do when they repeatedly read, the material is immediately accessible and processing is fluent and easy." Satisfied that the material seems familiar, we figure we know it—only to realize later that we don't. Keep yourself from falling into this trap by putting away notes and books and trying to recall the material from memory.

Mix it up. During training or studying sessions we often practice the same type of problem until we feel we've mastered it, then move on to the next kind of task. This can give us an overly confident sense that we know the material—until we're flummoxed by real-world conditions, in which problems don't come at us neatly arranged but rather randomly and unpredictably. Replicate these realistic conditions during training and studying by mixing up tasks so that you don't know which one is coming next. "Learners who train under such conditions," write psychologists Dominic Simon and Robert Bjork, "would be less likely to terminate practice before achieving the level of learning that is the goal of such practice."

Gain expertise. David Dunning, the psychologist mentioned above, notes that people who are beginners, or simply not very skilled in a particular domain, are "doubly cursed": "Their lack of skill deprives them not only of the ability to produce correct responses, but also of the expertise necessary to surmise that they are not producing them." In other words, when we're bad at something we don't even have the knowledge to know how bad we are. He has found that for students beginning study in a discipline, there is a weak relationship between what they believe their level of understanding is and their actual exam performance—but that this connection grows stronger as students become more advanced. To avoid overconfidence, heed the words of Confucius, the ancient sage: "Real knowledge is to know the extent of one’s ignorance." (Abstracts of the four studies mentioned here are available on my blog.)

(Want to read past issues of The Brilliant Report? You'll find them here.)