Deprivation and Incentive Motives

In one classic experiment, Carl J. Warden studied the persistence of behavior
as a function of various sources, including the strength of a drive, using
an apparatus called a Columbia obstruction box. He demonstrated that a rat
without food would cross an electrified grid to reach a goal box that held
food. When the rat was immediately brought back from the goal box to the
start box, it would cross the grid again and again. The number of grid crossings
was positively related to the number of days without food for up to three
days. From the fourth day without food, however, the number of crossings
slowly decreased. When baby rats were placed in the goal box, a mother rat
would cross the grid repeatedly. When a male or female rat was placed in the goal box, a rat of the opposite sex would cross repeatedly. The number of
crossings by the male rat was positively related to the duration it spent without
a female companion.

These animals were all manifesting the effect of different drives: hunger,
maternal instinct, or sex. It was shown that the maternal drive was associated
with the greatest number of crossings (twenty-two times in twenty minutes),
followed by thirst (twenty times), hunger (seventeen), female sex drive
(fourteen), male sex drive (thirteen), and exploration (six). Warden demonstrated
that various internal forces, created by deprivation and hormonal
state, and external forces, created by different goal objects, together determine
the grid-crossing behavior. The level of deprivation induces drive motivation;
the reward in the goal box induces incentive motivation. In this example,
the focus is on drive motivation.

If one were to place a well-trained rat into a maze, it might or might not
run to the goal box. Whether it would run, how fast it would run, and how
well (in terms of errors) it would run would depend upon whether the subject
were food-deprived. With food deprivation, the well-trained rat would
run to the goal box with few errors. If it had just been fed, it would not run; it
would simply wander, sniff at the corner, and go to sleep. The environmental
stimulus (the maze) is the same; the rat’s behavior is different because
the internal force—the drive created by food deprivation—is different. A
need state produces D, and D then triggers behavior. The behavior that will
occur is determined jointly by the past experience of learning, which is
termed H, as well as stimuli, S, from the environment. An inexperienced rat,
without the H of maze running, will behave differently from a well-trained
rat in a maze. D is an intervening variable: It connects need and behavior, so
one must consider both the source (need) and the consequence (behavior)
to define D. When D is zero, there will be no maze running, no matter how
well-trained the rat is. On the other hand, if there is no H (training), the
proper maze-running behavior will not occur, no matter how hungry the rat
is. An animal must be exposed to a maze when hungry to learn to negotiate
the various turns on the way to the goal box containing food. Without food
deprivation (and the resultant D), the animal would not perform, even if it
could; one cannot tell whether an animal has the knowledge to run the
maze until one introduces a D variable. H is a potential of behavior, and D
makes the potential into the observable reality of performance. Motivation
turns a behavior on.

These ideas can be applied to countless real-life examples. If a person is
not very good at playing tennis (has a low H), for example, no matter how
motivated (high D) he is, he will not be able to beat a friend who is an expert
at the game. If a person is very good at tennis (high H) but does not feel like
playing (low D), perhaps because of a lack of sleep, she will not perform
well. The same situation would apply for taking a test, delivering a speech, or
running a marathon.