This brings us to our definition of private stimulus. A private stimulus is a physical energy change capable of affecting a sense organ that affects only one individual; other individuals are not affected. Features irrelevant to the classification of private stimuli include the type of energy change and the function of the stimulus.
Is a physical energy change
Is capable of affecting a sense organ
Affects only one individual; other individuals are not affected
Type of energy change
Function of the stimulus (e.g., reinforcing, discriminative, punishing)