In the previous section we discussed walking and turning on a stage to illustrate how physical action can be analyzed in terms of the movement of bones and joints. We illustrated, with greatly simplified images, how muscles can control the rotation of bones about joints. Since muscles can only contract or relax, they can only pull but not push. It therefore requires a pair of muscles to manage the rotation about a joint in a single plain.
The strength of the pull exerted by a muscle is controlled by a set of neural connections to the muscle. The more of theses neural connections fire, i.e. send an electric impulse to the muscle, the harder the muscle will contract, and thus the harder the muscle will pull.
The neural firing pattern of the neurons in the set for a single muscle can be seen as a set of zeros and ones, i.e. as information sent to the muscle.
We see vision and an action with a response. We therefore use the same approach to rotating the eyeball to direct the line of vision.