As stated in Section 1-2, a fundamental precept of science is empiricism: scientists must make direct observations that allow them to either confirm or disconfirm a claim. Because subjective definitions of concepts may affect our observations negatively, thereby not allowing us to convincingly confirm or disconfirm a claim (see previous section), scientific researchers must define their concepts objectively. An objective definition involves defining a concept in terms of a specific set of observations that can be verified by any competent observer. An observation that is verifiable is one that others are able to check for themselves. For example, we may objectively define the concept of a hot classroom as any classroom in which the temperature, as measured by a standard room thermometer, is at least 78º F (25º C). Or we may objectively define the concept of superior intelligence as any score on the Stanford-Binet Intelligence Scale of 116 or higher. In this course, I have objectively defined an A, B, C, D, and F (see the syllabus). That is, I don't rely on subjective impressions of how much a particular student has learned when assigning a grade to that student; the grade assigned (the observation made) depends entirely on the scores received on tests and assignments, with those scores being weighted according to a particular formula. Any competent observer should be able to test the accuracy of the observation (the grade assigned) by obtaining the student's scores and placing them into the formula.

Thus, objective definitions differ radically from subjective definitions. Observations based on objective definitions are not affected by arbitrary factors limited to the individuals making the observations — factors such as personal feelings, whims, or uninformed opinions. Furthermore, objective definitions differ from dictionary definitions. A dictionary definition consists of a general statement made about the meaning of a concept, whereas an objective definition specifies a set of directly observable (measurable) events that give meaning to a concept — events that ideally can be measured with precision. For example, the dictionary definition of empathy is, "the ability to share in another person's emotions or feelings" (see Webster's New World Dictionary, 2nd College Edition). This definition, however, does not indicate how we would measure the average degree of empathy in individuals. An objective definition of empathy, on the other hand, must indicate how to measure this concept. For example, we might objectively define empathy in infants as "the amount of time it takes to begin crying while listening to an audio-recording of another infant crying."

As you probably now can see, objective definitions are essential for the ability of scientific researchers to empirically test claims. This is because objective definitions have two major advantages:

• Conceptual Clarity. Researchers using the same objective definition must, by necessity, be studying the same concept. This becomes very important when researchers investigate complex and fuzzy concepts such as "intelligence."
• Verifiability. A verifiable observation (measurement) is one that can be chacked by others for its accuracy or truth. Concepts that are objectively defined are relatively easy to verify in this way.

Nevertheless, objective definitions also have an important disadvantage: they may provide us with observations with low validity.

Validity of Observations

A valid observation is one that tells us the extent to which individuals exhibit the characteristics of the concept in which we are interested. For example, a scale for measuring weight provides valid observations if the numbers that appear when people step on it actually reflect their weights. If, on the other hand, the scale is broken so that random numbers appear when people step on it, we would say that the measurements (observations) provided by the scale are not valid. A measure of something may have all degrees of validity from completely valid to completely invalid.

Objective defiitions of concepts affect validity in the following ways. First,objective definitions generally measure not only the concept being investigated, but also other concepts. For example, the concept of knowledge of the course material may be objectively defined as the combination of scores on six multiple-choice tests. Although this seems to be a straighforward way of measuring the concept, the operational definition also includes measurements of anything else that might affect test scores, such as test anxiety, verbal comprehension, reading rate, distractibility, and test wiseness (multiple-choice test strategies). Thus, one person may get a low score because he suffers from severe test anxiety. Another may get a low score because she was distracted by a student 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.

Second, objective definitions often cannot measure all aspects of a psychological concept because these concepts tend to be complex: they refer to a broad range of cognitions, emotions, and behaviors. For example, we might objectively define shyness as the total amount of time that a person avoids eye contact in a conversation with another person. Although this objective definition measures an important aspect of shyness, it should be obvious that the concept is more complex than can be captured by this single objective definition.

In order to minimize these two validity problems, researchers may use several objective definitions of a concept in their studies. Although each objective definition may measure only selected aspects of the concept, as well as concepts other than the one being studied, combining the observations from several objective definitions will tend to converge on the concept. For example, a teacher who wants to measure students' knowledge of the course material may use a variety of objective definitions: multiple-choice tests, essay tests, short quizzes, research papers, oral reports, class participation, reaction papers, and so on. Each objective definition has weaknesses; but, when considered together, they are likely to give a good idea of how much each student has learned in the course.

Testable Claims

If a researcher is unable to develop an objective definition of one or more concepts included in a claim, then that claim is untestable: in order to test the claim, its concepts must be linked to observable and verifiable events. Most psychological concepts can, with some ingenuity, be objectively defined. Nevertheless, there are some concepts for which there simply are no objectively observable and verifiable events that can be linked to them without including subjective elements, such as prior beliefs, values, and desires. For example, there probably are no objectively observable and value-free events that can be linked to the concepts of "evil" or "freedom." In general, any claim that includes a concept or concepts that cannot be linked to objectively observable and verifiable events is not testable. We will see in other parts of the text that this requirement has made it very difficult, if not impossible, to test some important claims made about mental events and behaviors.

Study Questions for Section 2-4

1. How would you define "objective definition" in your own words?
2. What is an example of an objectively defined concept from your everyday life?
3. What is an objective definition of "knowledge of the course material" other than the ones mentioned above?
4. What would be an example of an objective observation of an individual's:
   (a) amount of intelligence
   (b) amount of hunger
   (c) degree of interest in a visual stimulus
   (d) level of sexual desire
5. What characteristics might an objective definition of "bad eyesight " contain?
6. What are the advantages of using objective definitions in research?
7. What are the disadvantages of using objective definitions in research?
8. How can researchers reduce problems introduced by these disadvantages?
9. What is a testable psychological claim that you have learned in this course? What makes it a testable claim?
10. What is an untestable psychological claim that you have learned in this course? What makes it an untestable claim?

Go to Quiz 2-4 questions

Go to Readings Section 2-5