title: Darks are processed faster than lights.
abstract: Recent physiological studies claim that dark stimuli have access to greater neuronal resources than light stimuli in early visual pathway. We used two sets of novel stimuli to examine the functional consequences of this dark dominance in human observers. We show that increment and decrement thresholds are equal when controlled for adaptation and eye movements. However, measurements for salience differences at high contrasts show that darks are detected pronouncedly faster and more accurately than lights when presented against uniform binary noise. In addition, the salience advantage for darks is abolished when the background distribution is adjusted to control for the irradiation illusion. The threshold equality suggests that the highest sensitivities of neurons in the ON and OFF channels are similar, whereas the salience difference is consistent with a population advantage for the OFF system.
authors.affiliation: Graduate Center for Vision Research, College of Optometry, State University of New York, New York, New York 10036, USA.
authors.forename: Stanley Jose
authors.initials: SJ
authors.lastname: Komban
authors.forename: Jose-Manuel
authors.initials: JM
authors.lastname: Alonso
authors.forename: Qasim
authors.initials: Q
authors.lastname: Zaidi
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D000704:Analysis of Variance; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*