Earlier we mentioned that Skinner's (1957) functional analysis of verbal behavior seeks to discover the environmental variables that control various instances of verbal behavior. Skinner's classification system is based on common controlling variables. These variables include reinforcers, SDs, and establishing operations. We will review some definitions before proceeding with the classification system.
A reinforcer is a stimulus that increases the frequency of a behavior because it was presented as a consequence of that behavior.
An SD is a stimulus in the presence of which a behavior is more likely to produce a reinforcer. SDs are further classified into those that are verbal (i.e., the product of someone else's verbal behavior) and those that are nonverbal.
Establishing operations are motivational variables. They alter the effectiveness of stimuli as reinforcers and temporarily strengthen behavior that has previously produced those stimuli. A common establishing operation is deprivation. For example, being without food for a long time increases the effectiveness of food presentation as a reinforcing consequence for any behavior that produces it and increases the likelihood of behavior that has previously resulted in food presentation
A response product is the natural stimulus outcome of a response. For example, the response product of saying "BOO!" is the auditory stimulus "BOO!"
Point-to-point correspondence between an SD and a response product means that subdivisions of the SD are related to subdivisions of the response, but the resemblance need not be physical. For example, when taking dictation, after hearing the word "cat" you write the word cat. There is point-to-point correspondence in the sense that the "c" sound controls writing the letter c, the "a" sound controls writing the letter a, and the "t" sound controls writing the letter t.
Formal similarity between an SD and a response product means the SD and response product are in the same sense mode and they physically resemble each other. For example, after hearing someone else say "BOO!" you say "BOO!" The sense mode of both the SD and the response product is auditory and they sound the same. (When the SD and response product have formal similarity, they necessarily also have point-to-point correspondence.)
On the following pages are some of the verbal operants as classified by Skinner (1957), as well as some updated categories by Michael (1993, Chapter 12; see also Peterson, 1978). These are some of the basic building blocks upon which a functional analysis of more complex verbal behavior is built (e.g., autoclitics, self-editing, and thinking). We will deal with pure examples, although as Skinner (1957) notes: "(1) the strength of a single response may be, and usually is, a function of more than one variable and (2) a single variable usually affects more than one response." (p. 227)