Test four different formats in the hero — a static screenshot, a 3-second looping GIF, a custom illustration, and a 15-second auto-playing muted video — measuring time-on-page, scroll depth, and CTA click rate per variant. Each format triggers different cognitive cues: screenshots prove the product exists, GIFs show motion-as-proof, illustrations simplify abstractions, video tells story. The winner is usually category-shaped, not aesthetic-shaped.