 [P]erception is a state of multiple simultaneous readiness for actions directed to the objects in the environment that are acting on the receptor organs at any one moment. The actions in question have been acquired by the individual in the course of his life and have been determined by the reinforcing contingencies in the environment in which he grew up. What determines the content of perception is not the properties of the sensory transducers that are operated on by stimulus energies from the environment, but the properties of the behaviour conditioned to those stimulus energies…. (1965: 1, our emphasis)