Dimensionality of the Perceptual Space of Achromatic Surface Colors N Umbach, J Heller |
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Research Methods and Mathematical Psychology, University of Tübingen, Germany
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| The perceptual space of achromatic colors is often viewed as being one-dimensional, ranging from white to black over all shades of gray. In a series of experiments we tried to systematically investigate the dimensionality of achromatic color space. Experiments were conducted in an illuminated room insuring that all stimuli were perceived as surface colors. Results show that context free stimuli (simple gray patches) can be represented with a single perceptual dimension. Introducing surrounds in a second experiment shows that we need a second perceptual dimension to represent the color of the infield with these more complex stimuli. The shape of the psychometric functions in this second experiment is closely related to the perceptual dimensionality for these stimuli. In a third experiment, we wanted to investigate the form of these two-dimensional psychometric functions for same-different judgments conducted on infield-surround configurations for individual observers. The form of these psychometric functions shows that one perceptual dimension is not enough to explain what we perceive when looking at infield-surround stimuli. |
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