The Contingency of Perceptual Processing: Context Modifies Equal-Loudness Relations

The relative loudnesses of tones that differ in sound frequency can depend strongly on the stimulus context, that is, on the set of intensity levels in the stimulus ensemble Using a new paradigm, called matching in scaling, this investigation sought to confirm that context modifies loudness relations per se, and not, for example, only overt responses To this end, two experiments revealed that changes in stimulus context differentially affect direct comparisons of loudness of 500-Hz and 2,500-Hz tones, as well as numerical judgments of individual tones—when loudness matches and scaling judgments alike are obtained in the same experimental sessions These contingent effects vary dynamically over time as a function of the recent stimulus history A third experiment revealed analogous effects in a simple matching paradigm, with no numerical judgments at all These findings support the contention that basic properties of loudness perception—grounded in auditory processes often considered “low level”—nevertheless can be deeply contextual