Demo Bias

Demo bias is the documented tendency of judges to score teams with more polished presentations and more confident presenters higher than teams with comparable or stronger underlying work. The bias is most pronounced under science fair judging conditions, where brief structured visits give judges limited time to evaluate underlying technical depth and the surface impression carries disproportionate weight. The Eventflare hackathon judging guide cites a University of Southern California study finding that judges tend to be biased toward teams that are more extroverted and confident and that have more polished presentations. See fair-judging.

Demo bias is one of the three named manifestations of cross-domain bias, alongside hardware-stage bias and rubric mismatch. The bias is structurally bound to the science fair format rather than separable from it, which is why the storytelling principle storytelling-is-not-optional treats demo craft as part of the work rather than as a corrective for unfair judging — the bias exists, the bias will not be eliminated by willing it away, and the practitioner response is to treat presentation as load-bearing rather than to wish judges scored differently. See cross-domain-bias and science-fair-judging.