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Weber's law 1:17
A 77-second explainer of Weber's law, narrated over the same demo you can try yourself.
Try the interactive Weber's law demo
What this video covers
Weber's law states that the smallest change we can notice in something is proportional to its starting size, not a fixed amount. A £1 rise on a £3 coffee is glaring; the same £1 on a £900 laptop is invisible. The "just-noticeable difference" scales with the baseline, so big things have to change by a lot before anyone perceives it.
The same £1 jumped out on the cheap item and vanished on the dear one - because what we notice is a proportion of the starting size, not an absolute amount. That's Weber's law. It's why a tiny tweak reads as "broken alignment" on a small element but not a large one, why emphasis has to scale with context to be felt - and why small, repeated price creeps slip by unnoticed.
