What principle of psychophysics is demonstrated here: When you first arrive at a zoo, all you can smell is the animal feces, but about half way through your visit, you don't notice the smell anymore (Note: the amount of animal feces in the zoo has not changed during your visit).
Sensory adaptation it is the reduction of our sensitivity to stimuli that do not change. Adaptation occurs after constant exposure to a stimulus, our nerve cells start firing less frequently.
