Features that are irrelevant to the classification of a stimulus as verbal include its modality (such as auditory, visual, etc.), its dynamic characteristics (such as size, intensity, etc.), and its functions (such as discriminative, reinforcing, punishing, etc.).
A physical energy change capable of affecting an organism’s sensory receptors that has the following features:
It has a specific form or pattern which, as a unit, has controlling effectiveness
It is the result of verbal behavior
Modality: auditory, visual, etc.
Dynamic characteristics such as size, intensity, etc.
Function: discriminative, reinforcing, punishing, etc.