In search of stimuli

"If the brain were unable to fill in gaps and bet on meagre evidence, activity as a whole would come to a halt in the absence of sensory inputs. In fact we may slow down and act with action in the dark, or in unfamiliar surroundings, but life goes on and we are not powerless to act. Of course we are more likely to make mistakes ... but this is a small price to pay for gaining freedom from immediate stimuli determining behavior, as in simple animals which are helpless in unfamiliar surroundings. A frog may starve to death surrounded by dead flies; for behavior ceases when imagination cannot replace absent stimuli."

Richard L. Gregory, "Eye and Brain" (4th edition)
quoted in Rita Carter, "Mapping the Mind" (1998) Orion, London. pp. 194, 195.