title: Contrast inconstancy across changes in polarity.
abstract: In this study, we show that negative polarity noise patterns appear to have a higher contrast than positive polarity noise patterns with identical expected Fourier amplitude spectra. This demonstrates a failure of contrast constancy over changes in pattern polarity. An examination of local contrast measures shows that negative polarity noise has a wider distribution of local contrast values than positive polarity noise. We propose that the difference in apparent contrast between the two patterns may be based upon spatial non-linearities in the combination of local contrast measures.
authors.affiliation: Department of Psychology, University College London, UK. c.benton@ucl.ac.uk
authors.forename: C P
authors.initials: CP
authors.lastname: Benton
authors.forename: A
authors.initials: A
authors.lastname: Johnston
mesh_terms: D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D008029:Lighting; D008960:Models, Psychological; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D012684:Sensory Thresholds