Studies from the Bryn Mawr college Laboratory. The effect of the brightness of background on the appearance of color stimuli in peripheral vision.

Abstract

The present investigation is a direct continuation of one carried out in 1903-4 in the Mt. Holyoke laboratory. 1 The results of this earlier paper were based on observations of the appearance of the colors at the red-yellow end of the spectrum when seen in peripheral vision, and were in brief as follows :I. The brightness of a colorless background has a decided effect: (1) On the limits for yellow and orange, the limits for the former color being much wider with the darker grounds, for the latter color wider with the lighter grounds. (2) On the tone of red, orange and yellow, the component of the color least like the background in brightness being emphasized in every case -namely, the red with the light background, and the yellow with the dark background. Orange, which showed a greater variation than any other color, appeared as red with the light backgrounds at the same degree of eccentricity at which it appeared yellow with the dark backgrounds. The brightness of the background seems to have no effect on blue.II. After-images are often experienced at the periphery even when the tone of the stimulus color is not seen.A monograph by Dr. Baird, 2 which appeared after our paper had gone to the printer, gives the results of an investigation of peripheral vision under conditions of dark adaptation. His 'PSYCHOI,. REV., Vol. XII., 1905, pp. 386-425 : 'The Effect of the Brightness of a Colorless Background on the Extent of the Color Fields and on Color Tone in Peripheral Vision.' 1 J. W. Baird, ' The Color Sensitivity of the Peripheral Retina,' Carnegie Monograph, May, 1905. 2 5 26 GRACE MAXWELL FERNALD.conclusions, based on results obtained under invariable conditions of background and adaptation, have a bearing on our problem, since they represent the extreme case of dark adaptation and of brightness, contrast between stimulus and background. They are in brief as follows t 1 (i) " With a slight luminosity of stimulus, all colors appear colorless at the periphery of the retina." (2) "When they are brought in far enough to appear colored, those of the red end of the spectrum first appear yellowish or yellow, while those of the blue end first appear bluish or blue. . . ." (3) After-images, ' in the ordinary sense of the term,' were reported in but few cases, and then only when the paracentral regions of the retina were stimulated. Latent after-effects, however, seemed to persist after the stimulation, and to be influential in determining the color-effect of succeeding stimuli, when too short an interval was allowed between tests.In December, 1905 , J an investigation reported by Miss Gordon and Miss Thompson at the Harvard meeting of the American Psychological Association, gives detailed results, showing the effect of a colorless background on the color tone and on the frequency of occurrence of the after-image. The results, as summarized in the PSYCHOLOGICAL BULLETIN, are as follows : 3 "Finer discriminations are made in the red-yellow end of the spectrum than in the blue-green end, both in stimulus and after-image,...

Indicators of perception: I. Subliminal perception, subception, unconscious perception: An analysis in terms of psychophysical indicator methodology.

“…A tone previously reported unheard is shut off; this change is then reported by S in experiments by Dunlap (47), Dunlap and Wells (48), and Jastrow (91). Colored afterimages to color reported unseen were obtained by Fernald (59), challenged by Titchener and Pyle (183), and reaffirmed by Ferree and Rand "under the right conditions" (60, p. 196). These results were again obtained by the same authors (61), and by Newhall and Dodge, who found that "thresholds for after-images were lower than for stimulus color" (128, p. 8).…”