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Chapter 3
Lesson 6: Operational Definitions
In Lesson 5, it was stated that adequate evidence must be collected to test a claim such as
"antidepressant medications reduce the symptoms of major depression." But how do we
know when evidence is adequate? The remaining lessons will all, in one way or another,
attempt to answer this very difficult question. In the present lesson, we will begin
constructing an answer by addressing the following question: what are the specific
meanings of the terms ("concepts") in a claim? This is an important question because the
evidence we collect in testing a claim will depend, in part, on the meaning of the concepts
it uses. For example, in order to collect evidence that can test the claim about
antidepressant medications, we need to know what is meant by the concept "major
depression."
A concept is a generalized idea of a category of events. In other words, a concept is a
term that represents a group of actual objects or situations. For instance, the word "desk"
is a concept that refers to objects that have legs and on which one writes, draws, or reads.
It differs from the concept "table," which refers to objects that have legs and on which
one performs a number of functions (such as eating, playing games, and so on). It is very
difficult to express in words exactly how desks and tables differ from one another,
especially given the fact that one can eat on desks and can write or read on tables.
Nevertheless, in everyday life we rarely get confused by these two concepts: a group of
people usually can agree on which objects are desks and which objects are tables.
What about the concepts we use in psychology? There are two difficulties with
psychological concepts that may cause confusion when trying to test a claim. First, unlike
concepts referring to physical objects such as desks and tables, psychological concepts
such as "stress" and "intelligence" refer to unobservable mental phenomena. We make
inferences about these concepts by observing people's behavior (and other directly
observable events). For example, we can infer something about the intelligence of people
by observing their scores on IQ tests. Second, a particular psychological concept may
mean different things to different researchers. This has been a problem with use of the
term "stress": As your book notes, some have viewed stress as a stimulus event that
presents difficult demands (a divorce, for instance), while others have viewed stress as
the response of physiological arousal elicited by a troublesome event. It should be
obvious that researchers who use the same term to refer to what are actually different
concepts would not be understood by each other.
Operational Definitions of Concepts
Because of the difficulties mentioned in the previous paragraph, we need to carefully
define the concepts we use when making a claim in psychology. Because science is
"empirical" (that is, science is based on direct observations of nature), the definitions of
scientific concepts must involve events in the natural world that can be measured directly.
Such definitions are called "operational definitions." An operational definition refers to
a set of observable measurements that give meaning to a concept. For example, we
may operationally define the concept of "temperature" as the readings on a thermometer
rather than our subjective feelings of hot, warm, cool, and cold. As another example, we
may operationally define the concept of "intelligence" as scores on a particular IQ test
rather than a subjective impression of how bright or dull a person seems to be. Thus,
there are two advantages to using operational definitions. (1) By operationally defining
our concepts, we can be certain that all researchers who make use of the same
operational definition will be studying the same thing. (2) Operational definitions
prevent subjective impressions from influencing our observations.
The claim that "life changes are a form of stress" was mentioned in the textbook. The
meaning of the concept of "stressful life changes" is one that probably would differ
widely among different researchers; and its measurement could be influenced by
subjective biases. Thus, in order to make sure that different researchers are studying the
same thing, and studying it in an objective manner, an operational definition of the
concept had to be developed. One operational definition of the concept of "stressful life
changes" is "score on the Social Readjustment Rating Scale" (SRRS). By linking various
life changes with particular numerical values related to the amount of stress, the SRRS
provides an objective measure of stress.
Problems With Operational Definitions
Although operational definitions help us to avoid some important problems, their use
introduces other problems. The major problem introduced is that a particular operational
definition may measure other concepts in addition to the one we wish to measure. This is
a problem mentioned in conjunction with the SRRS. It was noted in the textbook that,
because the SRRS contains a larger number of negative than positive life changes, scores
on the scale may be measuring frustration in addition to change. This makes it difficult to
interpret the results of research that makes use of the SRRS.
Let's look at another example of this problem. The concept of "knowledge of the material
in this course" (that is, the one you are taking right now) may be operationally defined as
"the average score on five multiple-choice tests." This seems to be a straightforward way
to measure knowledge of course material. But this operational definition may be
measuring concepts other than simply knowledge. Here is a partial list of possibilities:
level of test anxiety, verbal comprehension, reading rate, distractibility (especially if there
are frequent disturbances occurring in the room during tests), and "test wiseness"
(strategies you have learned for taking multiple-choice tests). Thus, one person may get a
low score because he becomes very anxious whenever he is tested. Another may get a
low score because she was distracted by the student next to her who kept tapping a
pencil. A third person may get a low score because he is a slow reader and the test had a
time limit. And so on. In none of these cases is lack of knowledge necessarily the cause
of the person's low score.
In order to minimize this problem, researchers may use a variety of operational
definitions when they are trying to measure a concept. Although each operational
definition will tend to measure concepts other than the one being studied, the concepts
measured will tend to differ from one operational definition to the next. For example, a
teacher who wants to get a good estimate of the amount of knowledge each student
acquires in a course will use a variety of measurements: multiple-choice tests, essay tests,
short quizzes, research papers, oral reports, class participation, reaction papers, and so
one. Each operational definition has weaknesses; but, when considered together, they
should give a good idea of how much each student has learned.
Testable Claims Require Operationally Defined Concepts
If we are unable to develop an operational definition of one or more major concepts in a
claim, then the claim is untestable. That is, in order to test a claim, its concepts must be
linked to observable events that can be measured. With some ingenuity, most concepts
can be operationally defined in ways that many people would accept. But there are some
concepts that cannot be operationally defined because there simply are no observable
events that can be linked to them. For example, it would be very difficult to operationally
define concepts such as "virtue" or "freedom": these concepts are so complex and abstract
that there seems to be no specific observations to which they could be linked. Similarly,
one could not operationally define supernatural events: by definition, they are beyond our
ability to observe. Although some people claim that supernatural events have effects in
the natural world that might be observable, it is impossible to be certain that the cause of
these natural events was something that occurred in a supernatural realm (but see Vuletic,
1997). The main point you should remember is this: any claim mentioning a particular
concept cannot be tested until that concept has been operationally defined.
Critical Thinking Questions
Question 6-1
Social anxiety refers to feeling anxious about being in particular social situations, such as
speaking in public, going to parties, and so on. Here is a description of social anxiety
from the Social Phobia/Social Anxiety Association web site:
In public places, such as work, meetings, or shopping, people with social anxiety feel that
everyone is watching, staring, and judging them (even though rationally they know this
isn't true). The socially anxious person can't relax, "take it easy", and enjoy themselves in
public. In fact, they can never fully relax when other people are around. It always feels
like others are evaluating them, being critical of them, or "judging" them in some way.
The person with social anxiety knows that people don't do this openly, of course, but they
still feel the self-consciousness and judgment while they are in the other person's
presence. It's sometimes impossible to let go, relax, and focus on anything else except the
anxiety and fear. Because the anxiety is so very painful, it's much easier just to stay away
from social situations and avoid other people altogether.
Develop your own operational definition of social anxiety. Make sure that your
operational definition of social anxiety allows you to distinguish it from problems
associated with other emotions, such as anger or depression.
Suggested Answer
Question 6-2
A question sometimes asked by people is, "can computers think?" In order to answer this
question scientifically, we would need to measure the ability to think. Develop an
operational definition of "thinking" that might allow you to answer the question about
"thinking computers."
Suggested Answer
Question 6-3
Which of the following claims are testable and which are untestable?
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Stealing is immoral.
"Slips of the tongue" are expressions of unconscious desires.
Murderers have a mental disorder.
Murderers are evil.
Most people have some psychic ability.
Lester loves Viola.
Ghosts are the spirits of deceased individuals.
Sugary drinks improve memory for factual information
Brain activity causes mental activity
Question 6-4
A study investigating alcohol use in young people stated that "44 percent of students on
college campuses can be classified as binge drinkers." Binge drinking in males was
operationally defined as "five or more drinks on one occasion," whereas binge drinking in
females was operationally defined as "four or more drinks on one occasion." Think
carefully about these operational definitions and discuss whether or not you agree that
44% of college students should be labeled as "binge drinkers."
Suggested Answer
Bibliography and References
Liebowitz Social Anxiety Scale. (u.d.). Retrieved March 13, 2002, from
http://www.psychmeds.com/liebowitz.html
Seavey, T. (March 27, 2002). Mobocracy, the skeptical environmentalist, and statistics.
Health Facts and Fears.com. Retrieved March 27, 2002, from
http://www.healthfactsandfears.com/editors_rants/objectivity/2002/mobocracy031202.ht
ml
Social Phobia/Social Anxiety Association. (u.d.). Retrieved March 13, 2002, from
http://www.socialphobia.org/
Stanovich, K. E. (2001) How to think straight about psychology (6th ed.). New York:
Longman.
Turing, A. (1950). Computing machinery and intelligence. Mind, 59, 433-460.
Vuletic, M. I. (1997). Methodological naturalism and the supernatural. Retrieved March
13, 2002, from http://www.infidels.org/library/modern/mark_vuletic/ntse.html