Physiological psychology is a behavioral science. The behavioral significance of a stimulus depends on its capacity to produce a neural impulse. Receptors convert environmental stimuli into neural impulses. The conversion process is known as transduction. The receptor is a biological transducer.
Receptors share certain features with neurons.
Like neurons, they have a resting potential, they also depolarize when stimulated. The depolarization is know as a generator potential. The actual process by the brain converts the impulses transduced by receptor cells into sensations is know as coding. Visual capacity varies considerably among different species. In very simple animals, such as certain inserts.