Confidence often gets treated as a personality trait, something people either have or don’t, closer to eye color than to a skill. Two studies looking at confidence from very different angles, one a massive statistical synthesis of workplace performance, the other a tightly controlled experiment on interview outcomes, suggest it behaves more like a lever that can be pulled, with real, measurable effects on how people actually perform.
The clearest evidence comes from a 1998 meta-analysis by Alexander Stajkovic and Fred Luthans, published in Psychological Bulletin, which statistically combined 114 separate studies covering 157 effect sizes and a combined 21,616 people. The researchers were testing self-efficacy, a person’s belief in their own capability to succeed at a specific task, against real, measured performance outcomes. Across the pooled studies, they found a weighted average correlation of .38 between self-efficacy and performance, translating to roughly a 28 percent average performance gain among people with high self-belief compared to those with low self-belief. The effect held up in both laboratory settings and real workplace field studies, and it was strongest on complex tasks, the kind where believing you can handle something arguably matters most.
A second study helps show how confidence can be built in the moments right before it’s needed, not just accumulated over a career. In a 2015 study by Amy Cuddy, Caroline Wilmuth, Andy Yap, and Dana Carney, published in the Journal of Applied Psychology, 61 university students were randomly assigned to spend five to six minutes alone, with no one watching, either in an expansive, high-power posture or a contractive, low-power one, before going into a mock job interview. Evaluators who didn’t know which condition each student had been in rated the high-power posers as significantly more hireable than the low-power posers, a fairly large effect. Notably, what people actually said in the interview didn’t predict how hireable they were rated, it was their nonverbal presence, how captivating and enthusiastic they came across, that drove the difference.
Together, these two studies point to confidence as something with real downstream consequences, not just an internal feeling. Stajkovic and Luthans’s research shows that believing in one’s own capability tracks with meaningfully better performance across a huge range of real tasks and settings. Cuddy and colleagues’ research shows that confidence, or at least the outward presence associated with it, can be deliberately cultivated in the minutes before a high-stakes moment, and that other people pick up on that presence even when the actual content of what’s said stays the same. Between the two, confidence looks less like a fixed trait and more like a state that both shapes and can be shaped by what a person does right before it counts.
It’s worth being honest about what these two studies don’t establish. Stajkovic and Luthans’s meta-analysis is correlational at its core, and while the consistency across 114 studies is a real strength, it can’t fully rule out that people who are already skilled simply also feel more confident, rather than confidence itself driving all of the performance gain. Cuddy and colleagues’ study is also worth flagging carefully: it’s a follow-up to an earlier, more famous power-posing study whose claims about hormone changes failed to replicate and are no longer considered credible. This later study measured only observable, evaluator-rated hiring outcomes rather than hormones, which is a more defensible claim, but the broader research area remains genuinely debated, and a single 61-person study is not the final word.
Within those honest limits, the research offers a reasonable, two-part picture of confidence worth taking seriously. It appears to be something that compounds over time through real belief in one’s own capability, built through experience and practice, and something that can also be nudged in the short term through small, deliberate acts of preparation before a moment that matters. Neither study suggests confidence alone guarantees success. Both suggest it’s doing more real work than a simple feeling would.