The verbal operants (mand, tact, echoic, intraverbal, and the rest) are tidy categories, but real talk is rarely that tidy. Skinner pointed out that a single verbal response usually has several sources of control, and that a single source usually strengthens several responses. That idea is called multiple control, and it explains a lot of what you see in sessions.
Why it matters
Multiple control is behind both your best teaching tools and some of your most misleading data. Prompting works because you add a second source of control to a response that is weak. Probes mislead you when an extra source of control sneaks in, such as a picture left on the table while you test an intraverbal.
For task B.20, multiple control in verbal behavior, a definition alone is not enough. Practice with vignettes: spot every variable that contributed to a response, tell convergent from divergent control, and explain why a teaching procedure fades one source of control.
Key ideas
- Pure operants are the exception. Classifying a response as a pure mand or a pure tact is a simplification. In everyday settings, motivating operations (MOs), nonverbal stimuli, verbal stimuli, and the audience often act on the same response together.
- Convergent multiple control: many variables, one response. Two or more variables add strength to the same response at the same moment. A thirsty child who sees a water bottle and says "water" is responding to both the MO and the bottle.
- Divergent multiple control: one variable, many responses. A single variable strengthens several different responses. One glimpse of a dog can make "dog," "puppy," "Biscuit," and "Look!" all more likely.
- The two work together. Divergent control makes several responses available; other variables, such as the audience or the exact question asked, help determine which one actually occurs.
- The audience is a source of control. The listener present affects what is said, which language is used, and how much is said. A bilingual teen may say "gracias" to his grandmother and "thanks" to his coach.
- Prompting relies on convergent control. In a transfer of stimulus control procedure, you present a prompt (often an echoic model) along with the target stimulus. The response is under both sources, and fading the prompt shifts control to the target stimulus alone.
Definitions
- Multiple control: the general fact that verbal responses are usually a function of more than one variable, and that one variable usually affects more than one response.
- Convergent multiple control: a single verbal response is strengthened by two or more controlling variables acting at the same time.
- Divergent multiple control: a single controlling variable strengthens two or more different verbal responses.
- Audience control: the listener functions as a source of control that, together with other variables, influences which verbal responses occur.
- Mixed (impure) operants: responses under blended control, such as a tact partly controlled by an MO, sometimes called a mand–tact blend or impure tact.
Examples from a session
Spotting the sources of control
- MO plus object (convergent): Before snack, Omar, 4, sees the cracker box on the clinic counter and says "cracker." Food deprivation and the sight of the box both strengthen the same word.
- Two verbal stimuli (convergent): A teacher asks Zoe, 9, "Name a red fruit." "Apple" is strengthened by "red" and by "fruit" together. Neither word alone would make "apple" as likely.
- One stimulus, many responses (divergent): At recess, a fire truck drives by. Students call out "fire truck," "siren," "loud," and "whoa." One event strengthened many responses.
- Prompting as added control: Hassan, 6, is learning to tact a whisk. His BCBA holds it up and says "whisk," and he repeats it. Over later trials she delays and then drops the model, so the whisk alone evokes the word.
- Audience control: Mei, an adult client, tells her job coach about a mistake at work in detail but gives her supervisor a short summary. The listener shaped what she said.
- Non-example (not divergent control): Lily, 7, says "cookie" whenever she sees cookies, whether her mom, her teacher, or her RBT is nearby. That is one response occurring across several listeners, not one variable strengthening several different responses.
When you analyze a response, list every variable present right before it: the MO, nonverbal stimuli, verbal stimuli, and the listener. Then ask which of them the response depended on.
Common mistakes / exam traps
- Assuming every response has one cause. If a stem includes both a motivating condition and an object, the answer is often "multiply controlled," not a pure mand or pure tact.
- Flipping convergent and divergent. Convergent means the arrows point in to one response. Divergent means they spread out from one variable to many responses.
- Confusing divergent control with response generalization. Response generalization is about untrained responses that are similar to a trained one. Divergent control is about one variable strengthening several responses, which may all have their own learning histories.
- Mixing up the vocabulary. Multiple control is a verbal behavior concept. A multiple schedule is a compound reinforcement schedule. Same word, different topic.
Exam trap
To classify a response, list every source of control present. One response with two or more sources means convergent control; one source feeding several responses means divergent control.
Exam trap
Pure intraverbal vs. a convergently controlled answer. A correct "milk" to "What do you pour on cereal?" counts as an intraverbal only if the spoken question is the source. The trap: a picture, model, or gesture left in view adds a second source, so the answer may depend on it. Remove the extra stimulus and probe again before you call the skill independent.
Quick check
On a walk in the park, Ana, 3, spots a ladybug on a bench and says 'bug!', then 'ladybug,' then 'red!' What does the ladybug's effect on her speech best illustrate?