Weber-Fechner Law
We perceive changes in proportion to the original value, not in absolute terms.
The Weber-Fechner law describes the relationship between physical stimulus intensity and human perception. We notice a change relative to the baseline: a 1 kg change in a 10 kg weight is very noticeable, but in a 100 kg weight, the same change is imperceptible. This explains why a $10 discount feels substantial on a $15 item but trivial on a $1,000 appliance.
What it looks like in the wild.
- Marketing Pricing Perception Shoppers drive across town to save $10 on a $20 calculator but won't bother to save $10 on a $1,000 TV, even though $10 is $10.
Recognising a definition is not the same skill as spotting it.
Two scenarios from the app, with distractors drawn from the same family of biases — which is what makes them hard.
Anna saves $50 on a $100 purchase and feels like a genius. She feels indifferent when she saves $100 on a $1,000 purchase.
A manager receives a 1% raise on a $100,000 salary and is disappointed. But when a junior colleague gets a 5% raise on a $40,000 salary, the manager thinks that's a huge increase, even though the dollar amount is smaller.
Biases rarely arrive alone.
Understand more. Assume less.
188 biases, 18,869 scenarios, and a record of how you actually decide.
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