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Topic: Just noticeable difference

	Just noticeable difference - Wikipedia, the free encyclopedia
		In psychophysics, the just noticeable difference (usually abbreviated as jnd, using lowercase letters) is the smallest difference in a sensory input that is perceivable by a human being or other animal.
		For many sensory dimensions, the jnd is an increasing function of the base level of input, and the ratio of the two is roughly constant.
		The jnd is a statistical, rather than an exact quantity: from trial to trial, the difference that a given person notices will vary somewhat, and it is therefore necessary to conduct many trials in order to determine the threshold.
	en.wikipedia.org /wiki/Just_noticeable_difference (402 words)

	Encyclopedia: Just noticeable difference
		In fact, the just noticeable difference, the threshold at which a change in pitch is perceived, is about five centss, but varies over the range of hearing and is more precise when the two pitches are played simultaneously.
		Musically the frequency of specific pitches is not as important as their relationships to other frequencies - the difference between two pitches can be expressed by a ratio or measured in centss.
		The initial standard was A=, but this was superseded by A=440 Hz after complaints that 439 Hz was difficult to reproduce in a laboratory owing to 439 being a prime number.
	www.nationmaster.com /encyclopedia/Just-noticeable-difference (799 words)

	The Use of Cents for Expressing Musical Intervals
		The just noticeable difference in pitch must be expressed as a ratio or musical interval since the human ear tends to respond equally to equal ratios of frequencies.
		It is convenient to express the just noticeable difference in cents since that notation was developed to express musical intervals.
		Evaluating the just noticeable difference in pitch by the "nickel's worth" rule is convenient, but as you might expect it is an oversimplification.
	hyperphysics.phy-astr.gsu.edu /hbase/music/cents.html (450 words)

	Classics in Psychology (Site not responding. Last check: 2007-10-03)
		Just as a curved line can be charac-terized at every point by both concavity and convexity, all nature, Fechner argued, can be as readily viewed from the psychical as from the physical perspective.
		A just noticeable difference is the minimum reportable difference in intensity of sensation brought about by a minimal change in physical stimulus intensity.
		Fechner’s own contribution was to recognize that the just noticeable difference could be made the basic unit of measurement of the intensity of sensation.
	www.thoemmes.com /psych/fechner.htm (1069 words)

	Weber's Law of Just Noticeable Difference
		The Difference Threshold (or "Just Noticeable Difference") is the minimum amount by which stimulus intensity must be changed in order to produce a noticeable variation in sensory experience.
		Ernst Weber (pronouned vay-ber), a 19th century experimental psychologist, observed that the size of the difference threshold appeared to be lawfully related to initial stimulus magnitude.
		This is accomplished by plotting the "percent correct judgment" on the y-axis as a function of the "difference in line size" (delta I) on the x-axis.
	www.usd.edu /psyc301/WebersLaw.htm (642 words)

	Frequency Just Noticeable Difference
		Don't worry about saying "same" or "different" an equal number of times, just mark whether or you not you hear the tones as the same, or different.
		For each JND task, the first column contains the physical change presented (in Hz) and the second column records how many times you said that the two tones were the "different" (out of three possible).
		Discuss similarities and differences of the discrimination functions among the frequencies.
	webphysics.davidson.edu /faculty/dmb/soundRM/jnd/jnd.html (398 words)

	Loudness Units: Phons and Sones
		The loudness of complex sounds can be measured by comparison to 1000Hz test tones, and this type of measurement is useful for research, but for practical sound level measurement, the use of filter contours has been commonly adopted to approximate the variations of the human ear.
		The use of the phon as a unit of loudness is an improvement over just quoting the level in decibels, but it is still not a measurement which is directly proportional to loudness.
		A useful general reference is that the just noticeable difference in sound intensity for the human ear is about 1 decibel.
	hyperphysics.phy-astr.gsu.edu /hbase/sound/phon.html (438 words)

	Classics in the History of Psychology -- First Annual Meeting of the American Psychological Association (1892)
		When the just noticeable difference (or an apparently equal difference) is used in the former sense, the judgment of the observer is probably based on association with the known relations of the physical world.
		Thus there are differences which are nearly always correctly perceived and differences which are nearly as likely to be perceived incorrectly as correctly, but the ideas of an absolute just noticeable difference or of an absolute threshold become absurd.
		Perhaps the explanation is to be referred to a proper difference in the successive movements of the eyes -- the pleasingness of difference being a general contrast phenomenon the ultimate explanation of which is to be sought for in conditions of a general nature and not by reference to the eye alone.
	psychclassics.yorku.ca /APA/meeting1.htm (3621 words)

	Gale Encyclopedia of Psychology: Just noticeable difference (Site not responding. Last check: 2007-10-03)
		When we try to compare two different objects to see if they are the same or different on some dimension (e.g., weight), the difference between the two that is barely big enough to be noticed is called the just noticeable difference (JND).
		Just noticeable differences have been studied for many dimensions (e.g., brightness of lights, loudness of sounds, weight, line length, and others).
		In assessing heaviness, for example, the difference between two stimuli of 10 and 11 grams could be detected, but we would not be able to detect the difference between 100 and 101 grams.
	www.findarticles.com /p/articles/mi_g2699/is_0001/ai_2699000190 (361 words)

	Chapter 3 Sense & Perception
		The difference, or just noticeable difference threshold (JND) is the smallest possible difference between two stimuli that can be detected half the time.
		The various types of electromagnetic energy differ in wavelength (which is the distance from one peak to another).
		There are many different kinds of sense receptors in the skin; some of these sensory receptors specialized to respond to just one kind of stimulus such as heat, pressure, or warmth.
	www.delmar.edu /socsci/Faculty/Weir/chapter3.htm (3463 words)

	When Death is Sought Assisted Suicide and Euthanasia in the Medical Context
		The care provided to dying or very ill patients, not just their treatment, is ------------------------------------------------------------------------------- (11) Several studies have demonstrated that factors independent of clinical considerations, including race, economic status, and age, affect physicians'judgments about the course of treatment.
		Just as a physician's response can forestall or prevent suicide, a physician's ready acceptance of the patient's decision to accept suicide or euthanasia can encourage that outcome.
		This difference in moral agency, and the fact that it is the patient, not another person, who takes the final step, has significant implications for the risks posed by the practices.
	www.health.state.ny.us /nysdoh/consumer/patient/chap6.htm (11382 words)

	Psych 601 Unit 5 Module 2
		To experience a change in sensation which was "just noticeable," where the sensed increase is just one step, as from 1 to 2 or from 3 to 4 or from 13 to 14, then the stimulus would have to be increased by a constant fraction of itself.
		Just as the marksman centers his site, the chemist finely adjusts his microscopic glass, or the musician tunes his instruments, so the mind continues to draw marginal sensations to foveal, central, or sharpest vision (Hall, 1912).
		In Fechner's formula the "k" is that constant (or ratio) determined by the Weber law, which expresses the fractional increase necessary for a just noticeable difference.
	userwww.sfsu.edu /~psych601/unit5/652.htm (6055 words)

	Psychoacoustics and Music - Introductory Definitions
		Very small differences in frequency (less than a half tone) and loudness can be detected in successive tones that are not too short.
		Also the rate at which various partials rise with time and the difference in the relative intensity of partials with loudness are essential to the quality of a sound.
		Indeed it is at least in part the difference in relative intensity of partials that enables us to tell a loud passage from a soft passage regardless of the setting of the volume control.
	cara.gsu.edu /courses/MI_3110/psycho.html (2266 words)

	[No title] (Site not responding. Last check: 2007-10-03)
		Difference threshold or Just Noticeable Difference ("jnd") C. Subliminal perception People can be influenced by information of which they are not consciously aware D. Doubtful E. Psychophysical laws Weber's Law (1834) and difference thresholds Weber's law states that the Just Noticeable Difference between stimuli is a constant function of the intensity of the standard stimulus.
		The formula is: I / I = k, where I is the intensity of the standard, I is the size of the increase that produces a JND, and k is that ratio (Weber's constant) for the particular stimulus dimension.
		Because of this difference in width/flexibility, a given auditory frequency will produce a peak displacement of the basilar membrane that is greater at one location than at others, within certain limits.
	www.uwm.edu /~jcm/psy101/chapter.03/chapter.3.sensation.txt (1047 words)

	Sensory Thresholds: Difference Threshold (Site not responding. Last check: 2007-10-03)
		Minimum change noticeable at least 50% of the time it is presented.
		JND is a constant proportion of the stimulus.
		As the intensity of the original stimulus increases or decreases, the intensity of the jnd increases or decreases.
	core.ecu.edu /psyc/nowaczykr/intro/Ch03/tsld027.htm (54 words)

	Empirical Arguments for Phonetic Discreteness
		For a small enough difference, moving the difference along the continuum, one should (on the discrete category view) find discrimination flat spots (where the sounds are within the same sensory class) alternating with discrimination bumps (across a boundary between the sensory steps).
		These days, when a psychophysicist speaks of a `just noticeable difference', it is interpreted to mean enough difference that subjects have, say, a 75% chance of detecting the difference.
		On the other hand, it is known that if you give subjects a great deal of practice on just a single speech stimulus, listener's can respond in ways that reveal that their auditory resolution approaches the sensory limits observed for simple tones [Kewley-Port et al., 1988].
	www.cs.indiana.edu /~port/pap/manaster/node4.html (1545 words)

	Olympic Weightlifting - QWA - Articles - Weightlifting makes the Difference
		There is, in the obscure field of psychophysics, a law known as "the law of the just noticeable difference".
		It was found that the "just noticeable difference" was a constant relating to the level of the basic stimulus (which means that the fitter you get, the harder it is to improve above your level).
		Not a lot of gear is needed; just two 450mm pipes and about five metres of light chain with a hook or shackle in one end.
	www.qwa.org /articles/diff.asp (617 words)

	Dr. Kevin Nunley : What Prospects Look For When Choosing Your Product, Service, or Idea. (Site not responding. Last check: 2007-10-03)
		Just having spent a month getting aquainted with web design, she immediately noticed George's custom graphics, forms, and nifty columns--features that she could not figure out how to create.
		The answer, of course, is that sometimes you have to be MUCH better than the other guy before the average customer (who may not be an expert) starts to notice the difference.
		To the people who work at those stations, their contests are all very different, some better or more exciting than contests on other radio stations.
	www.pertinent.com /pertinfo/business/nunleyM6.html (742 words)

	Description of the JND lab (Site not responding. Last check: 2007-10-03)
		For each of four different standard lines, students judge which appears to be longer, the standard line or a comparison line.
		In doing the activity as a lab, the students combine their data and find the proportion of the time each length comparison line was judged to be longer than the standard line.
		The program uses the subject.num file to create a different subject number for naming the data file which is created each time the task is done.
	www.jcu.edu /psychology/jlarsen/jndscale.htm (472 words)

	Lucy tuning - Wikipedia, the free encyclopedia
		The LucyTuned perfect fifth is 0.0384 cents sharper than the fifth of 88 tone equal temperament, and a mere 0.01015 cents flatter than 3/10-comma meantone, and therefore is audibly indistinguishable from either as the just noticeable difference for pitch is five cents for single pitches.
		The difference is clearly audible, in the beating, if more than one pitch is sounded at the same time.
		Many musicians believe that extreme precision is significant in musical tuning, as different beat frequencies are heard, which are characteristic of each different tuning.
	en.wikipedia.org /wiki/Lucy_tuning (627 words)

	Psychophysics 1 (Site not responding. Last check: 2007-10-03)
		When the difference in frequency between the two tones is too small, both tones are judged as having the same pitch.
		This is true for order judgments for all psychophysical magnitudes: whenever the variation of an original physical stimulus lies within a certain difference limen or just noticeable difference (JND) the associated sensation is judged as remaining the same.
		The JND in frequency is not defined sharply.
	www.avatar.com.au /courses/PPofM/psychohearing/psycho1.html (303 words)

	Draft 1 - Methods for the Production of Graded Impairment...
		Visual threshold measurements, e.g., where one seeks to measure the "just noticeable difference" between two stimuli, requires relatively finely graded values of the stimuli of interest, at least in the neighborhood of the threshold.
		Moreover, in the case of video impairments, it may also be the case that different types of distortions vary with respect to their visibility and in their impact on subjective judgements of quality.
		For JND measurements suitable graded test material might be generated by either global or local mixing of reference video with corresponding frames of impaired video.
	grouper.ieee.org /groups/videocomp/1998g216/JLimpair1.html (1686 words)

	ZenerA: Reference [Just Noticeable Differences] (Site not responding. Last check: 2007-10-03)
		JND's are differences in sensory input that, under standardized conditions, are noticeable half of the time.
		Generally speaking a JND of 4 or less is undetectable in video applications.
		For sound applications a JND of is approximately equal to 1 Decibel.
	www.zenera.com /reference/jnd.html (167 words)

	[No title] (Site not responding. Last check: 2007-10-03)
		This noticeable difference varies for\par different kinds of stimuli being used and it is proportional to the initial amount of stimuli.\par 1) The Phi phenomenon works on the premise that a series of lights can take on the\par illusion of solitary movement if they were presented at a rapid speed.
		As you slow\par down the presentation of a series of stimuli the perception of the stimuli changes\par from movement of one object to the detection of separate lights being turned off\par and on in succession.
		Be specific in your methods of determining the JND (just noticeable\par difference) in the stimuli changes.\par c.
	www.uic.edu /classes/psych/psych352/catperdiscrimination.rtf (415 words)

	Ernst Heinrich Weber Biography / Biography of Ernst Heinrich Weber World of Health Biography
		That is, for any standard unit of 40, subjects would notice a difference if one more unit were added to the weight.
		The difference in perception meant that sensitivity to change was sharper if a person used two or more senses.
		Subjects noticed differences of one-sixtieth in light intensity, one-thirtieth in pain differences, one-tenth in pitch perception, one-quarter in smell, and one-third in taste.
	www.bookrags.com /biography-ernst-heinrich-weber-woh (736 words)

	Just Noticeable Difference in Random Dot Stereograms
		The JND, or difference threshold, is the smallest detectable difference between two stimuli (Goldstein, 1999).
		The JND was the depth level at which subjects answered "yes" 50% of the time.
		Therefore, the JND was shown to be seven depth levels (127-120).
	www.alma.edu /departments/psychology/sp2000/randot/randot.htm (813 words)

	Just Noticeable Difference
		The Just Noticeable Difference experiment was designed to determine the minimum difference in height between two bars that is noticeable.
		A log file is created that, for each trial, prints the heights of the bars, the difference, the response, the correctness, and the elapsed time.
		The results will be used to determine the heights of bars in future experiments.
	www.cs.uga.edu /~rhodes/JND/JNDHome.htm (126 words)

	Just noticeable difference (Site not responding. Last check: 2007-10-03)
		In psychophysics, the just noticeable difference (usually abbreviated as jnd, using lower case letters) is the smallest difference in a sensory input that is perceivable by a human being or other animal.
		S. Stevens argued that it would hold only for what he called prothetic sensory continua, where change of input takes the form an increase in intensity or something obviously analogous; it would not hold for metathetic continua, where change of input produces a qualitative rather than a quantitative change of the percept.
		If a different proportion is used, this should be included in the description - for example one might report the value of the "75% jnd".
	www.sciencedaily.com /encyclopedia/just_noticeable_difference (402 words)

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