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Updated: Jun 16, 2026

Perceptual and Category Processing of the Uncanny Valley Hypothesis' Dimension of Human Likeness: Some Methodological Issues
Published on: June 3, 2013
Parafoveal color discrimination: a chromaticity locus of enhanced discrimination
Marina V Danilova1, J D Mollon
1Laboratory of Visual Physiology, I.P. Pavlov Institute of Physiology, St. Petersburg, Russia. mvd1000@cam.ac.uk
Abstract:
Are boundaries between color categories associated with enhanced discrimination? In the present experiments, chromatic thresholds were obtained for discriminations along lines orthogonal to the yellow-blue axis of color space. The targets were parafoveal and thresholds were measured with a spatial two-alternative forced choice. In interleaved experimental runs, we also obtained empirical estimates of the subjective yellow-blue line by asking observers to categorize colors as reddish or greenish. Both types of measurement were made in the presence of a steady background that was metameric to equal-energy white. In a limited region from desaturated yellow to desaturated blue, an enhanced discrimination is found near the subjective transition between reddish and greenish hues. This line of optimal discrimination is not aligned with either of the cardinal axes of color space: In a MacLeod-Boynton chromaticity diagram, it runs obliquely with negative slope.
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