Controlling Variables

Skinner theorized that behavior has several kinds of consequences, or effects.
Events that follow behavior and produce an increase in the rate or frequency
of the behavior are termed reinforcers. In ordinary language, they
might be called rewards, but Skinner avoided this expression because he defined
reinforcing events in terms of the effects they produced (their rate of
occurrence) rather than the alleged feelings they induced (for example,
pleasure). To attribute the increase in rate of response produced by reinforcement
to feelings of pleasure would be regarded by Skinner as an instance
of mentalism—the attribution of behavior to a feeling rather than an
event occurring in the environment. Other consequences which follow a behavior
produce a decrease in the rate of behavior. These are termed punishers.
Skinner strongly objected to the use of punishment as a means to control
behavior because it elicited aggression and produced dysfunctional
emotional responses such as striking back and, in a small child, crying. Consequences
(reinforcers and punishers) may be presented following a behavior
(twenty dollars for building a doghouse, for example, or an electric
shock for touching an exposed wire) or taken away (a fine for speeding, the
end of a headache by taking aspirin). Consequences may be natural (tomatoes
to eat after a season of careful planting and watering) or contrived (receiving
a dollar for earning an A on a test).
Reinforcing and punishing consequences are one example of controlling
variables. Events that precede behaviors are also controlling variables
and determine under what circumstances certain behaviors are likely to appear.
Events occurring before a response occurs are called discriminative
stimuli because they come to discriminate in favor of a particular piece of
behavior. They set the occasion for the behavior and make it more likely to
occur. For example, persons trying to control their eating are advised to
keep away from the kitchen except at meal times. Being in the kitchen
makes it more likely that the person will eat something, not simply because
that is where the food is kept but also because being in the kitchen is one of
the events which has preceded previous eating and therefore makes eating
more likely to occur. This is true even when the person does not intend to
eat but goes to the kitchen for other reasons. Being in the kitchen raises the
probability of eating. It is a discriminative stimulus (any stimulus in the presence
of which a response is reinforced) for eating, as are the table, the refrigerator,
or a candy bar on the counter. Any event or stimulus which occurs
immediately before a response is reinforced becomes reinforced with the response
and makes the response more likely to occur again if the discriminative
stimulus occurs again. The discriminative stimulus comes to gain some
control over the behavior. 713