Showing papers in "American Journal of Psychology in 1960"

Basis for lightness-judgments of grays.

Abstract: The physival-correlate theory of sensory intensity has been suggested as a general rule governing judgments for all modalities.l The theory holds the estimates of sensory intensity are based upon experience with the manner in which sensory excitation is correlated with some physical attribute of the stimulus (not necessarily the one employed conventionally to describe stimulus-intensity). It is considered that the physical correlate upon which visual intensity-judgments are based is distance, .e. an individual's experience with the effect of distance from the light-source on the luminance of a reflecting object. Predictions based upon this theory have been verified recently for brightness-judgments by Warren and Warren,2 and the present etperiment was designed to test these predictions as applied totlightness' judgments. Warren and Warren found that estimates of the decrease in luminance of an object produced by doubling its distance from the light by one group of Ss were quantitatively equivalent to judgments of Ihalf-brightness by a second group. The authors stressed the point that for estimates of the eSect of changing distance from the illuminated Seld to its light-source to be accurate, contrast-effects with surrounds must be minimized by the use of large contiguous stimulus-fields. With gray papers as well, background-contrast has a considerable effect on 'lightness' judgments under conditions usually employed, hence these judgments depend not only upon the reflectance of the gray stimulus-papers but also upon the reflectance of the surrounds. In the presence experiment, an attempt was made to minimize the influence of contrast with stimulus-surrounds by having S make 'lightness'

Memory in Monkeys for Compound Stimuli

Abstract: The purpose of this paper is to describe the training of monkeys in a memory-task recently proposed by Konorski.1 This new method requires that the animal discriminate between two compound stimuli, each of which is made up of two signals within the same modality and separated by a short interval. As used by Konorski, a compound stimulus, consisting of two tones identical in pitch, is positive and is reinforced by food if it elicits the appropriate response from the animal (placing a forelimb on the food-tray).2 On the other hand, when the second signal is of a different pitch from that of the Erst, the stimulus is negative. It is not reinforced and the animal has to learn to leave the food-dispensing apparatus alone. In other words, the compounds Sx-Sx and Sy-SyX etc., are positive, while Sx-Sy and Sy-Sx are negative as long as 'x' differs from gy,