PSY 3108 Lecture Notes - Lecture 12: Visual Acuity, Rod Cell, Receptive Field
11 Dec 2016
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Hecht et al. determined the absolute for detecting a light under full dark adaption. Determined how many rod cells the threshold level light would effect. Results showed that only one photon was needed to excite a rod. This is the smallest amount of light possible in the universe. 7 photons hit a patch of 350 photo receptors so most likely each is absorbed by a different rod cell (7 balls vs 350 cups analogy) time-course of light adaption is usually much shorter. Usually less than a minute because it only requires that pigments be bleached. Dark adaption requires pigments to be regenerated after being bleached which takes longer. Neural circuit- group of neurons connected by excitatory and inhibitory links. We can understand simple ones like feature recognition, but still not face recognition. General principle of neural circuits: linear-high acuity low sensitivity. Linearity- chain of neurons one stimulating the next.
