BEHAVIORISMbehavior is said to be emitted because it does not
depend on an eliciting stimulus. Examples of
operant behavior include manipulation of objects,
talking with others, problem solving, drawing, read-
ing, writing, and many other performances. Con-
sequences select this behavior in the sense that
specific operants occur at high frequency in a
given setting. To illustrate, driving to the store is
operant behavior that is likely to occur when there
is little food in the house. In this situation, the
operant has a high probability if such behavior has
previously resulted in obtaining food (i.e. the store
is open). Similarly, the conversation of a person
also is selected by its social consequences. At the
pub, a student shows high probability of talking to
his friends about sports. Presumably, this behavior
occurs at high frequency because his friends have
previously ‘‘shown an interest’’ in such conversa-
tion. The behavior of an individual is therefore
adapted to a particular setting by its history of
consequences.
A specific operant, such as opening a door,
includes many performance variations. The door
may be opened by turning the handle, pushing
with a foot, or even by asking someone to open it.
These variations in performance have a common
effect upon the environment in the sense that each
one results in the door being opened. Because
each variation produces similar consequences,
behaviorists talk about an operant as a response
class. Operants such as opening a door, talking to
others, answering questions, and many other ac-
tions are each a response class that includes a
multitude of forms, both verbal and nonverbal.
In the laboratory, the study of operant behav-
ior requires a basic measure that is sensitive to
changes in the environment. Most behaviorists use
an operant’s rate of occurrence as the basic data
for analysis. Operant rate is measured as the fre-
quency of an operant (class) over a specified peri-
od of time. Although operant rate is not directly
observable, a cumulative recorder is an instru-
ment that shows the rate of occurrence as changes
in the slope (or rise) of a line on moving paper.
When an operant is selected by its consequences,
the operant rate increases and the slope becomes
steeper. Operants that are not appropriate to the
requirements of the environment decrease in rate
of occurrence (i.e., decline in slope). Changes in
operant rate therefore reflect the basic causal
process of selection by consequences (Skinner 1969).
Behavior analysts continue to use the cumula-
tive recorder to provide an immediate report on a
subject’s behavior in an experimental situation.
However, most researchers are interested in com-
plex settings where there are many alternatives
and multiple operants. Today, microcomputers
collect and record a variety of behavioral measures
that are later examined by complex numerical
analysis. Researchers also use computers to ar-
range environmental events for individual behav-
ior and provide these events in complex patterns
and sequences.CONTINGENCIES OF REINFORCEMENTBehaviorists often focus on the analysis of environ-
ment-behavior relationships. The relationship be-
tween operant behavior and its consequences de-
fines a contingency of reinforcement. In its simplest
form, a two-term contingency of reinforcement
may be shown as R(Sr. The symbol R represents
the operant class, and Sr stands for the reinforcing
stimulus or event. The arrow indicates that ‘‘if R
occurs, then Sr will follow.’’ In the laboratory, the
behavior analyst arranges the environment so that
a contingency exists between an operant (e.g.,
pecking a key) and the occurrence of some event
(e.g., presentation of food). If the presentation of
the event increases operant behavior, the event is
defined as a positive reinforcer. The procedure of
repeatedly presenting a positive reinforcer contin-
gent on behavior is called positive reinforcement
(see Pierce and Epling 1999).A contingency of reinforcement defines the
probability that a reinforcing event will follow
operant behavior. When a person turns the igni-
tion key of the car (operant), this behavior usually
has resulted in the car starting (reinforcement).
Turning the key does not guarantee, however, that
the car will start; perhaps it is out of gas, the battery
is run down, and so on. Thus, the probability of
reinforcement is high for this behavior, but rein-
forcement is not certain. The behavior analyst is
interested in how the probability of reinforcement
is related to the rate and form of operant behav-
ior. For example, does the person continue to
turn the ignition key even though the car doesn’t
start? Qualities of behavior such as persistence,
depression, and elation reflect the probability of
reinforcement.