In Chapter Four Skinner notes forms of control by verbal stimuli. One form is textual behavior which refers to the type of behavior we might typically call reading or writing. A vocal response is controlled by a verbal stimulus that is not heard.t is a behavior under the functional control of a verbal stimulus. The verbal response and the verbal stimulus share what is called point to point correspondence (a formal similarity.) The speaker repeats what is said. In echoic behavior, the stimulus is auditory and response is vocal.