Photoreceptors Rods “Blue” Cones “Yellow” Cones –“Green” –“Red”

Brightness Ranges in Vision Photopic: (Cone) –High light levels (daylight) –Cones –High acuity –Fast Scotopic: (Rods) –Low light level (night vision) –Rods –Low acuity –Slow Mesopic: –Twilight –Rods and cones

Dark Adaptation

Adaptation

Adaptation Test

Adaptation and After Effects Adaptation is a decrease in sensitivity during the adapting stimulation. An after-effect is a change in viewing other stimuli after the adapting stimulation ends.

Adaptation

Adaptation Test

Moiré Patterns produced by interactions between two repetitive patterns. Movement in some art may be due to after- effects interacting with the current view.

Photoreceptors and Light Photopigments absorb photons. –Rhodopsin, R,G,B cones all similar Starts chemical reaction Results in an electrical response. Dark adaptation changes the gain between absorption and electrical response.

Solso, 1994, p.11. Photopic (Cone) Sensitivity Perception of Brightness “Yellow” cones –Red + Green –Not “blue” Peak in yellow- green. Red and Violet very dark when no hue seen