Also, we are talking about stimuli that are the direct and immediate product of a prior response. When you click the “Play” button on a YouTube video, the visual stimuli that are the result of the scenes changing on the screen are not considered as response-products of the behavior of clicking on the “Play” button.
A stimulus with the following features:
It is the result of someone’s behavior
Formal or dynamic characteristics of the stimulus (e.g., mode or intensity)
Formal or dynamic characteristics of the response that produces it
The function of the stimulus (e.g., discriminative, reinforcing)