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Tufte goes into some detail on JND as it applies to graphic arts in
_Visual Explanations._ Chapter 4, "the Smallest Effective Difference,"
is an extended discussion of the topic.
Geoff hart wrote (in part):
> Tim Altom continued the thread: <<I don't think this has anything to do with
> Miller's cognitive studies, which focused on memory, not on perception. Rather,
> it has to do with the Just Noticeable Difference (JND), a common measure in
> A little of both, from what I recall. There was certainly a discussion of JND
> in "The magic number seven", but if memory serves, Miller also discussed the
> number of JNDs that study participants could distinguish at a single time, and
> that this, combined with the JND, determined how many items a participant could
> remember (in short-term memory). As you said:
> <<The JND varies a good deal depending on many factors, including the intensity
> of the stimulus. The lower the stimulus, the smaller the JND. The JND also
> varies a lot depending on which senses are involved. Your example of gray
> shading on graphs is just such an example of the JND. You might find that the
> shades needed varied according to the pixel density and how much area the gray
> covered on the page.>>