Modification of induced-hue responses by means of forced matching.

Abstract

Induced-hue matching responses are shown to be subject to a learning or conditioning effect. Munsell matches were made to a series of mixtures of red and tungsten light, viewed as test patches in a surround of the same two lights. Systematic forcing of the matches, during practice trials, produced modifications of the matching responses on test trials. Forcing consisted of restricting the Munsell hue ranges from among which the matches were made, but forcing was not extreme; it represented an abstract version of the responses of previous subjects to a similar set of stimuli. Six forced-match and six control subjects made 2592 matches, 864 from the critical pre- and post-forcing trials. In the forced-match group a strong blue or purple-blue component was added to nearly all hues. In each group, Munsell-value responses reflected the relative luminances of the stimuli, but tended to decrease slightly as a function of practice. Munsell-chroma responses were bimodally distributed and showed little change from early to late trials. Because of the experimental design, the hue shifts in the forced-match group are regarded as learning phenomena.