In the field of behavioral psychology, language is analyzed as a form of behavior, just like any other action. B.F. Skinner, a prominent psychologist, proposed a system for categorizing what he termed “verbal behavior” not by its form, but by its function. This focuses on understanding environmental variables that prompt speech, writing, or signing. This perspective helps us understand why individuals communicate in the ways that they do.
The Concept of Antecedent Control in Language
Understanding verbal behavior often begins by examining what happens before it occurs. These preceding events are known as antecedents, and they exert primary control over our language. Two main types of antecedents are: Motivating Operations and Discriminative Stimuli.
Motivating Operations, or MOs, are internal states that temporarily change the value of a specific reinforcer and the likelihood of behaviors that have been reinforced by that item. For instance, feeling thirsty makes water more valuable and increases the probability of asking for water. These operations are often related to biological needs or desires.
Discriminative Stimuli, or SDs, are external cues or signals that indicate the availability of reinforcement for a particular behavior. A stop sign, for example, is an SD that signals that stopping your car will be reinforced by safety and avoiding a traffic violation. SDs do not change the value of a reinforcer but rather signal its presence.
Verbal Behavior Controlled by Motivation
One type of verbal behavior directly controlled by a Motivating Operation is known as a mand. A mand is essentially a verbal request, demand, or command that specifies its own reinforcer.
When a person feels hungry, the MO of food deprivation makes food highly valuable, leading them to say “cookie” or “sandwich.” Similarly, a child who wants to be picked up might say “up,” with the desire for physical contact serving as the MO. Even asking “What time is it?” can be a mand, as the desire to know the time functions as the motivating operation for the question.
Verbal Behavior Controlled by Sensation
Another category of verbal behavior, known as a tact, is primarily controlled by a nonverbal discriminative stimulus. This means the verbal response is evoked by sensory experience—what they see, hear, smell, taste, or feel. The tact serves as a label or a comment about the environment.
For instance, upon seeing a dog, a person might say “dog,” with the sight of the animal being the nonverbal SD. Smelling popcorn might evoke the response “popcorn,” directly controlled by the olfactory stimulus. Similarly, feeling raindrops on one’s skin could lead to the statement “it’s raining,” as the sensation of rain serves as the controlling antecedent.
Verbal Behavior Controlled by Other Language
Verbal behavior can also be controlled by another person’s language, acting as a verbal discriminative stimulus. This category encompasses several distinct types of verbal operants, each with specific controlling variables.
An echoic response involves repeating what someone else has said. If a therapist says “ball,” and a child immediately says “ball,” this is an echoic behavior, directly controlled by the auditory stimulus of the therapist’s vocalization. The form of the response matches the form of the verbal stimulus.
An intraverbal response occurs when a speaker responds to another person’s verbal behavior with a different, but related, verbal behavior. This includes answering questions, such as responding “my name is Alex” to “What’s your name?”. It also covers filling in the blanks of common phrases, like saying “star” after someone recites “Twinkle, twinkle, little…”.
Two other forms of verbal behavior controlled by prior language are textual and transcription. Textual behavior involves reading written words aloud, where the written text serves as the discriminative stimulus. Transcription involves writing down spoken words, with the auditory verbal stimulus controlling the written response.
The Practical Importance of Functional Language Categories
Distinguishing between these functional categories of verbal behavior is important, particularly in clinical and educational settings like Applied Behavior Analysis (ABA). This framework provides a way to assess and teach communication skills. It moves beyond simply counting words a person can say to understanding how and why they use those words.
For example, a child might be able to say “apple” when they see a picture of one (a tact), but they may not be able to ask for an “apple” when they are hungry (a mand). Recognizing this distinction allows educators and therapists to design targeted interventions. Effective language programs must systematically teach all these different functions of communication to foster complete verbal repertoires.