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just noticeable difference

just noticeable difference In this historical psychophysics context, a just noticeable difference is the smallest change in sensation that can still be detected, and it may be taken as a unit for measuring sensation.

In this historical psychophysics context, a just noticeable difference is the smallest change in sensation that can still be detected, and it may be taken as a unit for measuring sensation. In the account linked to Fechner’s law, such detectable differences are treated as proportional to the size of the stimulus.

Also see

Sources

Drafting source: Baldwin Dictionary of Philosophy and Psychology, 1901. 1901 New York Macmillan original; archive index checked 2026-10-18. “Fechner's Law” (Fechner's).
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PsychTerms (psychterms.org), CC BY 4.0, version 1. “just noticeable difference.” Development preview.

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