A model for perceptual analysis of the proximal stimulus into common and residual components, earlier described in a series of papers by Johansson and his co-workers for motion and space perception, is applied to colour perception. Though still premature, this application seems to make colour constancy a natural result of the analysis in the same way as size and form constancy is solved by Johansson's vector analysis in the frame of reference of projective geometry. Applications of the model to Land's Mondrian experiments, to simultaneous contrast, and to the Cornsweet-OBrien effect are outlined. The information from variations and invariances in reflected light (besides the geometrical projection) is discussed with reference to Gibson's ecological optics. phys. 14, 201-211.
It has often been reported that, in the absence of information about the direction of illumination, people interpret surface convexities and concavities in accordance with the assumption that illumination comes from above. However, 'above' could mean with reference to gravity, the head or the retina. Yonas et al reported that four-year-old infants use the head more than gravity as the frame of reference in interpreting surface relief but that seven-year-olds make about equal use of the two frames of reference. The potency of these two frames of reference when acting separately and when pitted against each other was measured on adult subjects. For all subjects the 'assumption' about the direction of illumination was predominantly with respect to the head. The gravitational frame was used only when the headcentric frame was irrelevant, and then not consistently.
Abstract.— According to Kirschmann's third law the induced colour is at its maximum when the inducing and induced fields are of equal luminance. Later studies (Kinney, 1962) show the induced colour to be most pronounced at a luminance ratio (inducing/induced) of about 4/1. In the present study the amount of colour induced into an achromatic test field was determined for one inducing colour, red, by letting observers judge the colour strength of the induced field. The test (or induced) field luminance was varied to give luminance ratios between 0.5/1 and 2/1. The results show that both colour strength and blackness increase as the luminance ratio is increased. The fact that the test field was judged even to have maximum chromatic colour strength and maximum blackness at the same time is discussed in relation to the method used and in relation to earlier studies on the “mode of appearance” of colours and the bidimensionality of achromatic colours.
Chromatic induction by red, green, and blue surround was studied as a function of surround/test field luminance ratio using a compensation method. Luminance ratios from 0.01 to 28.7 were used. The number of subjects was 8–10 in the three experiments. The results show maximum induction to appear at a luminance ratio around 1.0 when varying the test field luminance (Experiment 1) and at higher ratios when varying the surrounding luminance (Experiments 2 and 3). This difference is discussed in relation to the Kirschmann‐Kinney controversy (Kirschmann, 1890; Kinney, 1962) and in relation to an earlier study using a magnitude estimation method (Bergström & Derefeldt, 1975).
A homogeneous grey picture and a 'Mondrian' type of picture were illuminated by a projector with square-wave gratings of thirty different contrast values used as slides. Ten observers reported whether the picture appeared three-dimensional (3-D) (pleated) or flat. 3-D responses in this situation indicate colour constancy 'at the cost of' nonveridical depth perception. The frequencies of 3-D responses were significantly higher for the structured picture than for the homogeneous grey one. In reports of the direction from which the apparent 3-D object appeared to be illuminated there was a significant preference for responses "from above" when the grating was horizontally oriented. With vertical orientation there was no preference for "from the left" or "from the right". The results from the first experiment contradict traditional cue theories of depth perception since the projection of the borders between the fields of the structured picture was invariant and expected to inform about the flatness of the picture. They are, however, in line with a model for perceptual analysis of reflected light into common and relative components proposed earlier by Bergström. The difference in perceived direction of illumination between horizontally and vertically orientated gratings is discussed in connection with human ecology.
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