ABSTRACT
It is generally agreed that the highest form of measurement is achieved with ratio scales typified by the well-established scales used in the physical sciences such as those used for measuring length and mass. One of the major goals of the conference on the " Ratio Scaling of Psychological Magnitudes" was to evaluate the possibility that ratio scales of psychological magnitudes can be achieved, thereby imparting to psychophysical scaling the quantitative attributes of measurement that have been so important for the development of the physical sciences. There have been arguments that it is impossible to measure psychological magnitudes such as loudness, brightness. and pain intensity because they are private events (Savage , 1966, 1970; Zuriff, 1972) . However, we suggest, as did Stevens (1966) , that there is no fundamental philosophical difference that distinguishes physical measurement from psychophysical measurement. In both cases. observations are made by operations performed on the subject of interest. These observations form the basis for quantification of theoretical constructs such as force, gravity, electron velocity, and, in our opinion, sensation magnitude. We are hopeful that a careful consideration of progress in psychophysical scaling will eventually lead to the conclusion that true ratio scales for the measurement of psychological magnitudes, validated by the same criteria as those used in the physical sciences (e.g., meeting
1. INTRODUCTION 3
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neave, 1962; Curtis, Attneave, & Harrington , 1968; Shepard, 1981) merely redefines the problem as illustrated in Fig . I .2. Sensation magnitude (l\1) and its relation to stimulus intensity ( <!>), otherwise known as the psychophysical law [ l\J = f1 ( <!>) J, must be inferred from the relationship between the known stimulus and the subject's observable response [R = f3(¢)j. To do this , however, we must know the relationship between the response and sensation f R = fz( l\1) J. Unfortunately, the relationship between response and sensation is as inaccessible to direct observation as is the relationship between stimulus and sensation. In spite of these difficulties, psychophysical scales have been constructed and claims for their ratio properties have been made. These claims, as well as the claims of the critics, led us to discussions during the conference about another issue - whether or not results obtained with psychophysical methods can be used to indirectly construct scales of psychological magnitudes that meet the stringent requirements of ratio scales of measurement.
