Case file
Weber-Fechner Law
- Filed under
- Too Much Information
- Also recorded as
- Weber's law, Fechner's law
The charge
We notice differences in proportion to the starting level more than by absolute size. The same absolute change feels big in a small context and small in a large one.
How it operates
Perception is roughly logarithmic, so sensitivity decreases as magnitudes grow. Judgments track relative change, not just absolute change.
Logged incidents
- Incident 01
A 5 dollar fee feels outrageous on a 15 dollar item but trivial on a 500 dollar contract.
- Incident 02
A 2-point churn increase from 2 percent to 4 percent feels more dramatic than a 2-point increase from 20 percent to 22 percent.
- Incident 03
A 10,000 dollar raise matters far more at a 60,000 dollar salary than at a 400,000 dollar salary, even though the absolute increase is the same.
What to watch for
Ask yourself: 'Am I reacting to the raw difference, or to how large it feels relative to the starting point?'
Recommended action
Examine both absolute and percentage changes, and use log-scale charts where relevant. Percentage normalization makes comparisons cleaner.
Known associates
- AnchoringAn initial number, label, or piece of information pulls later estimates toward it, even when it is arbitrary…
- Conservatism BiasWe revise beliefs too slowly when new evidence arrives.
- Contrast EffectSomething looks better or worse depending on what it is compared with immediately before or beside it.
- Distinction BiasWhen options are compared side by side, we exaggerate small measurable differences that matter little in…
- Focusing effectWhen one salient detail is in focus, it pulls judgment toward itself and crowds out other relevant factors.
- Framing EffectEquivalent information leads to different choices depending on how it is worded or packaged.
Source of record