The claim overstates the evidence. While some studies find a small effect on self-reported feelings of confidence, this effect is modest and likely partly driven by participant expectations. The "success" component is not supported — multiple meta-analyses and replication studies find near-zero behavioral effect sizes. The original hormonal claims (testosterone/cortisol changes) were publicly disavowed by a co-author in 2016 after repeated replication failures. The research field has been significantly impacted by the replication crisis.

The best available evidence — including large pre-registered studies and meta-analyses — shows power posing produces a real but small effect on subjective feelings of power. It does not reliably change hormones, and behavioral or cognitive outcomes that would constitute "success" are weak or absent. The claim's use of "significantly" overstates the effect size, and pairing "confidence" with "success" implies downstream real-world benefits that the evidence does not support. The original 2010 findings have been substantially undermined by replication failures.