The primitives of a representation are the most elementary units of shape information available in a representation. - David Marr

The abstract properties of this mapping are defined precisely, and its appropriateness and adequacy for the task at hand are demonstrated.

To understand the relationship between behavior and brain one has to begin by defining the function, or computational goal, of a complete behavior. Only then can a neuroscientist determine how the brain achieves that goal.

[If] we can experimentally isolate a process and show that it can still work well, then it cannot require complex interaction with other parts of vision and can therefore be understood relatively well on its own.