Just-noticeable difference

The differential perception threshold (also JND of Engl. Just Noticeable Difference " just yet noticeable difference " ) called in psychophysics, a just nor sensible stimulus difference.

Measurement methods

Forced -choice tests are often used to determine differential Wahrnehmbarkeitsschwellen. Here, a subject several situations are presented with a definite difference. The subject here has the task to organize the situations according to certain criteria (eg, what noise is louder, which light is brighter, etc. ) During the experiments, the differences between the situations are becoming smaller. Above the discrimination threshold, the differences can be detected and classified correctly. If the differential visibility threshold is reached, no difference can be detected on the basis of their own perceptions, the classification of situations is purely coincidental. Through statistical analysis of the results of the transition can be detected in random information. This transition point is associated with the differential perception threshold.

Interval judgments ("? Hearing / seeing a difference " ) are rarely used for the determination of differential Wahrnehmbarkeitsschwellen because they are less accurate than forced -choice experiments: In the psychophysical experiment, in this case the subject is to determine the differential visibility threshold is a slow, but possible exposed continuously changing distal stimulus, such as a changing in amplitude or frequency sound to measure the precise definition of perception by the human ( and animal rare ) sense organs. Displays the test person a unique reaction because they can notice the stimulus difference and may also appoint increase or decrease of the stimulus, the difference of output and Endreiz is the differential visibility threshold.


It turns out that the perceptibility of differences is very low when the limits of visibility are achieved (very strong and very weak stimuli, lower and upper areas of perception ). Furthermore, there are considerable individual differences in subjects, such as Dependence of the measured results of age and physical disposition. The differential visibility threshold can be reduced by habituation or " training ": Musicians show a finer perception of frequency differences, chefs and sommeliers to sharpen the distinction of taste.