1. Sensory adaptation refers to

A. a weakening of a neurotransmitter substance
B. a perceptual inversion principle
C. a decline in sensitivity after prolonged stimulation
D. an increase in sensitivity after prolonged stimulation

2. The hormone _____ appears to play a key role in adjusting our biological clocks.

A. melatonin
B. cholecystokinin
C. serotonin
D. phenylalanine

3. The Impressionist technique of pointillism relies on the use of

A. subtractive color mixing
B. feature analysis
C. additive color mixing
D. binocular disparity as a cue for depth.