Context effects and the validity of loudness scales.

Abstract

In these experiments, Os were required to make half-loudness judgments with a method of constant stimuli. Each of 3 groups of Os was given a different non-overlapping range of variable stimuli to be judged with respect to a standard stimulus. The major results and conclusions are: (1) For each group the mean intensity required for half-loudness was not significantly different from the mid-point of the range of variable stimuli. Thus the judgments were made almost completely with respect to the context of presented stimuli. (2) Within each group there were large individual differences which were established early in the judgment series and were maintained over the entire series of judgments. It is concluded that such judgments are reliable but not valid for purposes of loudness scale construction. (4) It is further pointed out that Os in general do not seem able to describe sensory magnitudes with a scale of numbers. Thus sensory scale construction must depend on the use of converging operations which do not require the assumption of the valid use of number scales by Os.