Verbal behavior is the study of the function of language and the effect that a speaker has on a listener. Within this context verbal does not necessarily indicate the spoken word, but rather any form of communication including sign language, pecs, electronic and so on. B.F. Skinner, who first described and defined the term verbal behavior, developed the six following terms to describe six elementary verbal functions:
1. Echoics: A verbal operant under the control of verbal stimuli. Echoics are maintain by reinforcement. A parent says “cookie” then the child says “cookie”. 2. Mands: The desire for a particular outcome results in the use of signs, gestures, pointing, language, etc. in order to illicit the desired result. 3. Tacts: A verbal operant under the control of a prior controlling stimulus. A child sees a cat and says, “Cat”. The parent says, “Yes, that’s a cat. It’s a very pretty cat.” 4. Intraverbals/Sequelics. Verbal operants under the control of verbal stimuli. One person makes a comment, asks a question, etc. and a second person responds. 5. Autoclitics: Verbal behavior that modifies the effects of elementary verbal operants on a listener. Instead of just saying, “cookie” the speaker says, “cookie please” or “a big cookie please.” In these examples, the words big and please modify the request (mand). 6. Textual responding: Verbal behavior under the control of printed words. In other words, reading out loud.
Along with the above-mentioned, current research in the field of verbal behavior has been successful in identifying verbal milestones that organize the progress of verbal developmental stages. Integrating verbal functions and verbal milestones allows a higher likelihood of increasingly complex verbal development. Verbal milestones describe the level of verbal capability and thus, increase in difficulty. In order to determine a child’s level of ability, probes (or tests) will be conducted before beginning an intervention program.