A response may have more than one product. The same writing that produces marks on a piece of paper also produces visual stimuli related to arm movements; we can see that someone is engaged in writing. Furthermore, if it is quiet, some auditory stimuli may be produced as a result of the friction between pen and the paper. Additional response-products may be private; the movements resulting from writing also produce kinesthetic stimulation to which the writer may be able to react.
A stimulus with the following features: