Drives

Type of psychology: Motivation
Field of study: Motivation theory
A drive is a state influenced by an animal’s need; the animal is motivated to reduce
tension or to seek a goal. Drive theory is concerned with the nature of the internal forces
that compel an animal to behave.

Key concepts

• drive
• drive reduction
• law of effect
• need
• reinforcement

One goal of science is to understand, predict, or manipulate natural events.
A scientist may start by observing an event of interest and measuring it as
precisely as possible to detect any changes. In experimental research, scientists
systematically manipulate various other events to see whether the event
of interest also varies. In survey research, various events are measured to see
whether they vary with the event of interest. Understanding is achieved
when the relationship between the event of interest (the dependent variable)
and other events (independent variables) is established. One can then
predict or manipulate the event of interest. A theory provides a guideline to
organize the variables into a system based upon common properties. To a
psychologist, the dependent variable is the behavior of all animals and humans.
The independent variable (also called a determinant) may be any
other variable related to behaviors. Psychological research aims to discover
the determinants of certain behavior; some of them are motivational variables.
The field of motivation examines why particular behavior occurs, why
it is so strong, and why it is so persistent.

A drive is a process related to the source of behavioral energy originating
from within the body that is created by disturbances in homeostasis (a state
of systemic equilibrium). A homeostatic imbalance creates a state of need
for certain stimuli from the environment which can restore the balance. For
example, abnormal body temperature and hyperosmolality of the body
fluid (electrolyte concentration outside cells that is higher than that of the
intracellular fluid, resulting in cell dehydration) are disturbances in homeostasis.
The homeostatic balance can be restored through two means. Physiological
means such as vasodilation, sweating, and panting serve to reduce
body temperature; concentration of electrolytes in the urine by the kidneys
reduces hyperosmolality. Second, behavioral means such as taking off
clothes, turning on an air conditioner, and drinking cold liquid lower body
temperature; drinking water would also result in reducing the hyperosmolality. One may examine a case of homeostatic imbalance in detail to illustrate
how the two means function to restore the balance.

When the body fluid volume is reduced (hypovolemia) because of loss of
blood or of body fluid from intense sweating, the body responds immediately
by vasoconstriction, reducing urine volume (through vasopressin release),
and conserving sodium (through aldosterone release). Those are
physiological means that will restore the blood pressure and prevent circulatory
failure. Eventually, however, the body must get back the lost fluid from
the environment via behavior (seeking water and drinking) to achieve longlasting
homeostasis. The physiological means are immediate and effective,
but they are only stopgap measures. Behavior is the means with which the
animal interacts with its environment to get back the lost resource.