On Stevens's 'psychophysical law': A validation study

Mashhour, Madjid; Hosman, Jan

doi:10.1037/e572772009-001

Cited by 28 publications

(29 citation statements)

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“…Results with two different moduli yielded exponents of 1.33. Using similar procedures (the holding ofblocks between the thumb and the index or middle fingers), Mashhour and Hosman (1968), R. Teghtsoonian and M. , and Jones (1983) all measured accelerating ME functions with exponents in the range from 1.1 to 1.3, in agreement with cross-modal matching results (see the Appendix, Equation A3).…”

supporting

confidence: 70%

“…Furthermore, is there a difference between perceived span when the fingers are touching an object or not? To address these questions, I chose to follow the general methods of Jastrow (1886), Mashhour and Hosman (1968), and Chan et al (1990), and use mainly the simplest and most direct comparison of perceived span and length-eross-modal matchingto avoid variability introduced by individual differences in assigning numbers (see, e.g., Collins & Gescheider, 1989), or the tendency of subjects to use numbers corresponding to physical units of length (R. rather than sensation magnitude. In the first experiment, I also used a method in which the fingers were not in contact with test objects (bars, rods, or blocks) or a measuring device (sliding carriage), eliminating any information based on tactile cues.…”

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confidence: 99%

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Cross-modality matches of finger span and line length

Doren

1995

Perception & Psychophysics

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Perceived finger span-the perceived spatial separation between the tip ofthe thumb and the tip of the index finger-was measured by using cross-modal matching to line length. In the first experiment, subjects adjusted finger span to match the length of line segments presented on a video monitor, and conversely, with both hands. Subjects also made estimates of finger span in physical units ("dead reckoning"). Finger spans were measured by using infrared LEDs mounted on the tip of the thumb and the finger tip, so the hand made no contact with any object during the experiment. Unlike in previous studies, the results suggest that perceived finger span is proportional to line length and slightly shorter than the actual span, provided that corrections are made for regression bias. The effect of finger contact was assessed in a second experiment by matching line length both to free span and to spans constrained by the pinching of blocks in the same session. The matching function when subjects were pinching blocks was accelerating, consistent with previous reports. In contrast, matched line length was a decelerating function of free span. The exponent of the free span matching function in the second experiment was slightly smaller than in the first experiment, probably due to uncorrected matching biases in the second experiment.A person usually has no difficulty reaching for a glass of water and picking it up. It can be done even with the eyes closed after a couple of tries. There is, obviously, exquisite motor control based on visual and somatosensory information. But do the different sensory modalities tell us the same thing? For example, does the glass look as big as it feels? The question does not seem that interesting at first-surely the perceived size of the glass does not depend on whether it is looked at or is held in the hand. Experimentally, though, the answer depends on how the equivalence of size is measured. Magnitude estimates of span are nearly linear with respect to the actual distance between the tips of the index fingers of two hands held apart (Gogel, Wist, & Harker, 1963;Stanley, 1966;M. Teghtsoonian & R. Teghtsoonian, 1965). But the bulk of the experimental evidence suggests in contrast that the span perceived between the tips of the thumb and index finger of the same hand is a nonlinear function of the actual distance, is not veridical, and is not commensurate with perceived visual size.Jastrow (1886) provided the first such evidence by having subjects adjust finger span by sliding a movable carriage held between the thumb and index finger to match the length ofa viewed line (0.5-12 ern); or, to seThe author would like to thank Robert Teghtsoonian and Calvin Garbin for reviewing the manuscript and making many helpful comments and suggestions; Purwanto Suwondo, Lisa Menia, Jennifer Evans, and Michael Haines for technical assistance and data collection; and Robert Montz for making the blocks used in the second experiment. This work was funded by Grant NS27958 from the National Institutes of Health. Co...

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confidence: 70%

mentioning

confidence: 99%

Cross-modality matches of finger span and line length

Doren

1995

Perception & Psychophysics

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“…In summary, Table 4 shows a clear pattern of results with respect to response bias in the experiments of Mashhour and Hosman (1968) that has been overlooked up to this point. In particular, there appears to be consistent bias for each response continuum as the judged continuum varies.…”

Section: On Predicting Exponents In Magnitude Scalingmentioning

confidence: 97%

“…For example, in an article in which data of Mashhour and Hosman (1968) were analyzed, Stevens (1969), using the exponents obtained from 7 ME experiments, was able to predict, to an extent, the exponents obtained in 17 CMM experiments. Stevens viewed this as important validation evidence for magnitude scaling (see also Stevens, 1960Stevens, , 1966Stevens, , 1986.…”

Section: On Predicting Exponents In Magnitude Scalingmentioning

confidence: 99%

On bias in magnitude scaling and some conjectures of Stevens

DeCarlo

2005

Perception & Psychophysics

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“…In general, the matches to weak stimulus images tend to be above the diagonal line, and matches to strong images tend to fall below the line. It is difficult to interpret these results in a definitive manner because cross-modality matching of physical stimuli often leads to serious intransitivities (e.g., Baird et aI., 1980;Mashhour & Hosman, 1968), more dramatic than what is suggested by the data in Figure II.…”

Section: Solving For L In Equationmentioning

confidence: 38%