If we see an object strike someone, or see damage to the tissue, we assume that these visual stimuli are correlated with private stimuli resulting from stimulation of free nerve endings. If we see a rash on someone’s skin, we assume that the rash is correlated with private stimuli associated with itching.
A way in which the verbal community brings verbal behavior under the control of private stimuli that has the following features:
A private stimulus
A collateral public stimulus
Reinforcement for a given response contingent upon the presence of the public stimulus
The type of private stimulus
Whether or not there is any causal relationship between the public and private stimulus (they need only be correlated)