On predicting exponents for cross-modality matches

Mashhour and Hosman used magnitude estimations to scale seven continua: line length, time duration, finger span, loudness of noise, weight, gray reflectance, and surface area. The first four continua also served as the adjusted stimuli in 17 cross-modality matches among the various continua. Contrary to the view expressed by Mashhour and Hosman, the results appear to support the psychophysical power law. A reanalysis of the data shows that the exponents of the power functions obtained in cross-modality matches agree with the exponents of the power functions produced by magnitude estimations, provided correction is made for the regression effect. The measured discrepancies between the exponents predicted and those actually obtained show scatter that is consistent with that of other experiments. In particular, the scatter accords well with the distribution of 68 exponents predicted by Moskowitz from experiments in which Os matched both number and loudness to various taste concentrations.     

Subjective hardness of compliant materials

The apparent hardness and softness of nine samples of compliant materials were scaled by direct magnitude estimation and by cross-modal matches to the apparent force exerted on a hand dynamometer and a finger dynamometer, and to the loudness of a band of white noise. The physical hardness (force/indentation) of the compliant specimens covered a range of more than 100 to 1, extending from a fairly soft sponge to a fairly hard block of rubber. The apparent hardness of the specimens was found to follow the psychophysical power law. Subjective hardness grows as the physical hardness raised to a power. The indicated exponent was about 0.8 for magnitude estimation, about 0.7 derived by calculation from handgrip matches, and about 0.6 derived by calculation from loudness matches.

Numerical estimates and cross-modal matches for softness gave functions that were approximately the reciprocal of the functions given for hardness. Hardness is a continuum on which there exists an upper threshold.     

Brightness inhibition re size of surround

The amount by which the apparent brightness of a visual field is inhibited by a surrounding field depends on the area of the inhibiting field. Interocular brightness matches showed that, as the size of a surrounding annulus is increased from a thin ring, the degree of inhibition on the brightness of an inner disk increases rapidly at first and then more slowly as the effect approaches an asymptote. The increase of the inhibition with size of annulus can be expressed as an increase in the exponent of the power function that relates the apparent brightness of the dish to its physical luminance.     

Regression effect in psychophysical judgment

Psychophysical judgment, like all other kinds of judgment, involves a matching or equating of two different domains. When the judgment involves the mate hing of values on two perceptual continua, the observer tends, on the average, to constrict the range of his adjustments on whichever variable is placed under his control. When the observer adjusts each variable in turn, two different regression lines are produced. This regression effect presumably occurs whenever the results of the matching judgments yield less than a perfect correlation. Illustrative examples are given for the continua, loudness, vibration, brightness, and duration.