There is more here: Brains as output/input devices

Faced with novel situations, humans and most animals spontaneously increase their behavioural variability...

Controlling external events: the input

Thus, competitive success and evolutionary fitness of all ambulatory organisms rely critically on intact behavioral variability as an adaptive brain function. But relative freedom from environmental contingencies is a necessary, but most often not a sufficient criterion for such accomplishments. Tightly connected to the ability to produce variable behavior is the ability to use the effects of these behaviors to control the environment. The incoming stream of sensory information is noisy and fluctuates for any number of reasons. Any covariance between the behavioral variations and those of sensory input indicates that the latter are con-sequences of the behavior and can thus be controlled be the animal. This function is so paramount, that we humans express our delight over control of our envi-ronment (including other people) already as children, by e.g., shrieking in excitement when Daddy jumps after a “boo” or proudly presenting Mom with “look what I can do!”.