Suprathreshold contrast response in normal and anomalous trichromats

Kenneth Knoblauch, Brennan Marsh-Armstrong, John S. Werner

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Maximum likelihood difference scaling was used to measure suprathreshold contrast response difference scales for low-frequency Gabor patterns, modulated along luminance and L-M color directions in normal, protanomalous, and deuteranomalous observers. Based on a signal-detection model, perceptual scale values, parameterized as d0, were estimated by maximum likelihood. The difference scales were well fit by a Michaelis-Menten model, permitting estimates of response and contrast gain parameters for each subject. Anomalous observers showed no significant differences in response or contrast gain from normal observers for luminance contrast. For chromatic modulation, however, anomalous observers displayed higher contrast and lower response gain compared to normal observers. These effects cannot be explained by simple pigment shift models, and they support a compensation mechanism to optimize the mapping of the input contrast range to the neural response range. A linear relation between response and contrast gain suggests a neural trade-off between them.

Original languageEnglish (US)
Pages (from-to)A133-A144
JournalJournal of the Optical Society of America A: Optics and Image Science, and Vision
Issue number4
StatePublished - Apr 1 2020

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Computer Vision and Pattern Recognition


Dive into the research topics of 'Suprathreshold contrast response in normal and anomalous trichromats'. Together they form a unique fingerprint.

Cite this