Binocular contrast summation-II. Quadratic summation

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Quadratic summation is presented as a rule that describes binocular contrast summation. The rule asserts that for left-eye and right-eye contrasts CL and CR, there is an effective binocular contrast C given by the formula: C = √(CL)2+(CR)2 Pairs of left-eye and right-eye stimuli that produce equal values of C are equivalent. Quadratic summation is applied to the results of experiments in which stimuli presented to the two eyes differ only in contrast. It provides a good, first-order account of binocular summation in contrast detection, contrast discrimination, dichoptic masking, contrast matching and reaction time studies. A binocular energy-detector model is presented as a basis for quadratic summation.

Original languageEnglish (US)
Pages (from-to)385-394
Number of pages10
JournalVision Research
Issue number4
StatePublished - 1984


  • Binocular summation
  • Binocular vision
  • Contrast


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