Fechner's conception of psychophysics included both “outer psychophysics” the relation between stimulus intensity and the response reflecting sensation strength, and “inner psychophysics” the relation between neurelectric responses and sensation strength. In his own time outer psychophysics focussed on the form of the psychophysical law, with Fechner espousing a logarithmic law, Delboeuf a variant of the logarithmic law incorporating a resting level of neural activity, and Plateau a power law. One of the issues on which the dispute was focussed concerned the (...) appearance of contrasts if the overall illumination was increased or decreased; another issue was the question of whether a sensation of a “just noticeable difference” established for one value of a sensory dimension appeared the same for a value elsewhere on the dimension. The development of “inner psychophysics” led through the works of Delboeuf, Solomons, Jastrow, and Thurstone to modern signal detection theory. A third line of research, devoted to the question of what was meant by the “measurement” of sensation strength, stemmed from the criticism of Fechner's work by von Kries (1882) and others. Although a valid body of science could be built up without the intervening variable called “sensation strength,” such a science might be a cumbersome representation of reality. When an optical contrast is set up, and its overall illumination is increased or decreased, subjective contrasts involving medium levels of lightness vary little as illumination varies (as a power law based on sensation ratios or a logarithmic law based on sensation differences predict), but subjective contrasts involving extreme levels of lightness might be subject to the effects of other variables. (shrink)

During the interwar years psychologists Louis Leon Thurstone and Rensis Likert produced newly standardized forms of questionnaires. Both built on developments in mental testing, including the use of restricted sets of answers and the emergence of statistical techniques, to create questionnaires that employed numerical scaling. This transformation in shape of questionnaires was intimately tied up with both psychologists’ nominal subject of investigation: attitudes. Efforts to render psychology a socially valuable and influential science spurred psychologists to create sophisticated and increasingly precise (...) means of measuring social attitudes. Reducing mental dispositions to mere numbers on a scale, these developments also initiated new relationships between psychology and the public. Rather than engage a wide spectrum of the public directly in the research process, questionnaire research was limited to those within academic circles. Even so, research with questionnaires aimed to comment on attitudes in the public more broadly. The kind of ‘thin description’ afforded by numerical scales, though used to measure individual psychological subjects, afforded psychologists the opportunity to craft their vision of an increasingly attitudinal public, one positioned as best governed with the aid of psychological expertise. (shrink)