Just noticable difference

In selecting the stimulus continuum in threshold determination, the relation between just noticeable difference in relation to the intensity of stimuli is of interest. In accordance with Weber s law this quotient is assumed to be a constant. Therefore it would appear best to determine absolute thresholds on an intensity continuum in the form of a geometric progression. 

According to Beidler (1957), the threshold value of a substance depends on the equilibrium constant and the maximum response. Since K and Rs both vary from one substance to another and from one species to another, the threshold also varies between substances and species. The concentration of the stimulus can be increased in steps just large enough to elicit an increase in response. This amount is called the just noticeable difference (JND). 

Determining the threshold value is difficult because subthreshold levels of one compound may affect the threshold levels of another. Also, the flavor quality of a compound may be different at threshold level and at suprathreshold levels. The total range of perception can be divided into units that represent the smallest additional amount that can be perceived. This amount is called just noticeable difference (JND). The whole intensity scale of odor perception covers about 25 JNDs this is similar to the number of JNDs that comprise the scale of taste intensity. Flavor thresholds for some compounds depend on the medium in which the compound is dispersed or dissolved. Patton (1964) found large differences in the threshold values of saturated fatty acids dissolved in water and in oil. 

Cood, B.W, M.E. Parrish, and D.R. Douglas Volatile phase smoke profihng using gas chromatographic techniques 34th Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 34, Paper No. 15,1980, p. 8. Cordin, H.H., T.A. Perfetti, and R.W. Hawley Nicotine just noticeable difference study of full flavor low tar and ultra low tar non-menthol 85 mm products Tob. Sci. 32 (1988) 62-65. 

J.M. Rivers, L.A. Smith, and R.W. Hawley Nicotine just noticeable difference study of full flavor non-menthol 85mm products Tob. Sci. 30 (1986) 146-151. 

What importance does the just noticeable difference have on biological engineering designs ... 

IRAS infrared reflection-absorption spectros- JND just noticeable difference... 

Difference threshold (just noticeable difference). The smallest change in physical intensity of a stimulus which is perceptible. 

There are several definitions of threshold. The detection threshold is defined as the lowest stimulus eliciting a sensorial response, even though no identification can be reached. The recognition threshold or identification threshold is the level of stimulus at which the specific stimulus can be identified. The differential threshold or just noticeable difference, is the minimum increase in a stimulus required to detect a difference in the perception. 

We can experience very many just noticeable differences (JND s) of color. The JND, also known as the difference threshold or discrimination threshold, is the smallest change in any physical stimulation that can be observed with the unaided senses. There are a number of models and systems to standardize or predict resultant hues from mixtures of colors. Most notable of these are the standards of Ridgeway (1912), Munsell (1929), and various modifications of the Munsell system as found in the ISCC-NBS method of designating colors (Kelly and Judd, 1955), A Universal Color Language (Kelly, 1965) and the National Bureau of Standards (NBS) special publication 440, "Color. .. Universal Language and Dictionary of Names" (Kelly and Judd, 1976). There are more than 13000 color names in the NBS Special Publication 440. 

Uniform chromaticity scale diagram n. Any one of a variety of transformations of the CIE chromaticity diagram to a diagram on which all pairs of just noticeably different colors of equal luminance are represented by pairs of points separated by nearly equal distances. 

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