The Weber ratio for intensive discrimination.

Holway, Alfred H.; Pratt, Carroll C.

doi:10.1037/h0059748

Cited by 64 publications

(29 citation statements)

References 20 publications

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“…The decreasing Weber fraction with increasing standard, contraindicating Weber's law, is consistent with results in some other modalities, particularly the chemical senses (Holway & Pratt, 1936). The Weber fraction values are smaller than those usually reported for taste, thus emphasising the necessity of keeping volumes of liquid taste stimuli constant in gustatory comparison experiments to avoid providing a basis for a response bias or taste pseudo-discrimination.…”

Section: Discussionsupporting

confidence: 58%

Psychophysical parameters of the perception of orally-retained liquid bulk

Gregson

Matterson

1967

Perception & Psychophysics

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Bulk of liquid held in the mouth may be judged on its subjective volume. Over the range 1 ml-31 ml, scaling by the constant method and by ratio estimation yielded a Weber fraction which was not constant and decreased with stimulus magnitudes and a psychophysical power function with. an exponent of 0.96. A "negative thresho ld" effect is reported.The human capac'ty to hold liquid samples in the mouth without swallowing is accompanied by a limited ability to judge the relative bulk of such samples. Clearly, such judgments are mediated physiologically in a complex fashion. Cues to facilitate judgment are available from the weight, volume, viscosity, temperature, and taste of liquids, and also from resilience in the case of colloidal-phase stimuli (Szczesniak & Farkas, 1962). Under normal circumstances liquid samples are not weightless, and may not be tasteless. It is relatively easy to prepare tasteless samples. but without entering zero-gravity conditions weightless liquids are impractical. Therefore the term I 'liquid bulk" is used here to refer to the complex of sensations which result from holding a mass of tasteless liquid, of specified density, viscosity and temperature, in the mouth. S;ome cues of volume and weight are available to SSt and feelings resulting from tongue movements in liquid and consequent liquid flow through the interstices of the teeth may provide further cues. No attempt here has been made to distinguish information from these different potential sources;~he psychophysics of the normal unimpeded perception of liquid bulk as a gestalt quality is being investigated. The effective discriminability of water volume differences, and the psychophysical power function (stevens, 1961) relating perceived to actual volume (or weight) for water have been estimated. MethodSubjects. Thirty-six persons from the university campus, 18 males and 18 females, mainly first-year psychology undergraduates.Stimuli. Deionised water samples (equivalent to triple distilled in purity) with resistance not less than 2 MQ/cm were measured out from burettes into 50 ml beakers. The beakers were coated with opaque black and weighted inside with lead shot embedded in wax, to a varying unladen total varying between 95 and 105 gm, Thus the stimuli did not furnish consistent or facile visual or kinesthetic cues for Ss to guess volumes in advance of ingesting them.Procedure. The constant method (Guilford, 1954) and a paired comparison ratio scaling method (Comrey, 1950;Torgerson. 1958) were both used as two separate tasks, in a design balanced for order effects within and between tasks. Each S attended over three sessions. At each session the constant method with one standard, and a one-third part of the paired comparison matrix were completed.For the constant method, the volumetric series were (a) standard 5 ml, stimuli 3, 4, 5, 6 and 7 ml , (b) standard 15 ml, stimuli 12, 13.5, 15, 16.5 and 18 ml, (c) standard 25 ml , stimuli 21, 23, 25, 27 and 29 mi. Each S did all comparisons with a standard in both temporal orders once, m...

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Section: Discussionsupporting

confidence: 58%

Psychophysical parameters of the perception of orally-retained liquid bulk

Gregson

Matterson

1967

Perception & Psychophysics

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“…Textbooks often quote a Weber fraction of 0.02 for lifted weights, probably following Boring, Langfeld, and Weld (1939), who cited Holway and Pratt (1936). However, this appears to be a "best value" for one subject in one condition.…”

Section: Discussionmentioning

confidence: 99%

Sensorimotor mechanisms in weight discrimination

Brodie

Ross

1984

Perception & Psychophysics

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The role of efferent and afferent signals in weight discrimination was investigated by using the tonic vibratory reflex contraction ofthe biceps muscle. Differential thresholds were obtained for two lifting conditions (normal and reflex) and two static conditions (with and without muscular tonus). Normal lifting gave finer discrimination than reflex lifting (Experiment 1). Normal lifting was also superior to the two static conditions (Experiment 2). Within the static conditions, the addition of muscular tonus gave finer discrimination. The reflex lifting condition gave thresholds similar to those for static holding with muscular tonus, lying between those for normal active lifting and those for static pressure. The reflex lifting and pressure-sensing thresholds were very much finer than the previous literature suggests. The relative contributions of efference and afference to weight discrimination are discussed.The sensory mechanisms underlying weight perception have been debated for a century and a half. Weber (1834/1978) put it thus:The weight of an object is perceived in two ways: first by the touch-sense in the skin, and then by the special sense of the voluntary muscles. The latter sense tells us the degree of tension of the muscle when lifting weights and other objects.Weber went on to measure weight discrimination by the two methods, and concluded that purely tactile discrimination became more than twice as precise with the addition of muscular kinaesthesis. (In fact, he found average Weber fractions of about 1/3 for touch alone, and 1/14 for touch plus kinaesthesis.)In the latter half of the 19th century, extensive debate occurred over whether "sensations of innervation" or sensations from muscles formed the basis of the kinaesthetic sense. The issue was whether centrally generated (efferent) signals could be sensed in the same way as peripherally generated (afferent) signals, and it led to a great deal of fruitless controversy based on introspection and semantic hair-splitting. With the growth of experimentation and the understanding of sensory physiology, introspection as a method of scientific enquiry went out of use (Boring, 1942). However, a related debate continues in the area of motor skills. Instead of arguing about the nature of volition, modern psychologists and physiologists debate the difference between "closed-loop" and "open-loop" This work was supported by a Carnegie award to the first author, and by a grant from the Medical Research Council to the second author. We should like to thank J. R. Lackner for suggesting the TVR experiment, K. Gijsbers for suggesting the two-point discrimination experiment, and R. R. Macdonald for statistical advice.The authors' mailing address is: Department of Psychology, University of Stirling, Stirling FK9 4LA, Scotland. models of motor control (e.g., Stelmach, 1979), or "feedback" and "feed-forward" models (e.g., Roland, 1978). The interest is now in whether efferent information is used at all, either separately or in conjunction with afferent information, ...

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“…The deviation from Weber's law at low stimulus intensity occurs on most continua (Holway & Pratt, 1936). Therefore, if the JND scale is generated from an empirical Weber function and not, as has often been the case, from Weber's law or its linear generalization (e.g., Stevens, 1959Stevens, , 1961, it will be found to be less than logarithmic.…”

Section: Category Scalesmentioning

confidence: 99%