PSYC 4031 Chapter : Chapter 3 (Pgs.57-59)
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Spot of light is the test stimulus: threshold is measured using an ascending series of light intensities, after about thirty minutes dark adaptation is complete. Sensitivity is high and threshold is low: dark adaptation curve: the relationship between time in the dark and threshold or the intensity of light that an observer can barely detect. (figure below) In typical studies, researchers shine test stimulus on retinas where it might fall on both cones and rods (kink in the curve occurs about 5-10 minutes in the dark; first part cones second part rods) Threshold remains high still: testing dark adaption for rods is more difficult. In order to make testing more easy, you can test a monochromat: a person who has only rods in his/her retina. You"ll obtain a dark adaptation curve similar to the one in figure 3. 14. Figure corresponds to the aforementioned text. (not in the book)
