title: Effect of stimulus intensity on the sizes of chromatic perceptive fields.
abstract: The effects of intensity on chromatic perceptive field size were investigated along the horizontal meridian at 10 degrees temporal eccentricity by manipulating stimulus intensity from 0.3 to 3.3 log trolands. Following light adaptation, observers described the hue and saturation of monochromatic stimuli (440-660 nm, in 10 nm steps) for a series of test sizes (0.098-3 degrees) presented along the time period associated with the cone plateau of the dark-adaptation function. Perceptive field sizes of the four elemental hues (red, green, yellow, and blue) and the saturation component were estimated by three observers at each intensity level for each wavelength. In general, perceptive field sizes of blue and red are the smallest, and yellow and green are the largest. Furthermore, perceptive field sizes of all four hues decrease with increasing stimulus intensity, though the absolute change is largest for green and yellow. The decrease in size with increase in intensity cannot be completely explained in terms of saturation or rod signals and is likely, then, attributable to a cone-based mechanism.
authors.affiliation: Department of Psychology, Colorado State University, Fort Collins 80523, USA. ltroup@lamar.colostate.edu
authors.forename: Lucy J
authors.initials: LJ
authors.lastname: Troup
authors.forename: Michael A
authors.initials: MA
authors.lastname: Pitts
authors.forename: Vicki J
authors.initials: VJ
authors.lastname: Volbrecht
authors.forename: Janice L
authors.initials: JL
authors.lastname: Nerger
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology* / Q000528:radiation effects; D000328:Adult; D003118:Color Perception / Q000502:physiology* / Q000528:radiation effects; D015350:Contrast Sensitivity / Q000502:physiology* / Q000528:radiation effects; D004193:Discrimination Learning / Q000502:physiology / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods*; D011829:Radiation Dosage; D012684:Sensory Thresholds / Q000502:physiology* / Q000528:radiation effects; D014794:Visual Fields / Q000502:physiology* / Q000528:radiation effects