CSUF Department of Psychology
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Phenomena are the things that we have observed.  In science, this term usually refers to general observations as opposed to specific ones.  The fact that Todd is both under stress and depressed is not a phenomenon, but the fact that there is a statistical relationship between stress and depression is.  Similarly, the fact that my (Dr. Price's) baby, Vera, began smiling regularly at about two months of age is not a phenomenon, but the fact that babies generally begin smiling at around two months is.  Note that both of these examples involve a phenomenon that has been replicated many times.  That is, many studies have shown the relationship between stress and depression and many studies have shown that babies begin smiling at around two months.  This is part of what makes them phenomena (which are also often called "effects").  On the other hand, imagine that one researcher does a study showing a positive relationship between receiving an allowance as a child and being financially responsible as an adult, and a second researcher does a study showing a negative relationship.  Given just these two studies, we would probably not want to promote either result to the status of "phenomenon."  We would simply have two conflicting results awaiting further research.

Note that the singular form of the word in question is "phenomenon" and the plural is "phenomena."  So we might say, "That is a very interesting phenomenon."  Or we might write, "These three phenomena have yet to be explained."  We would never ask, "What is your favorite psychological phenomena?"  And we would never write, "There are several relevant phenomenon."  Finally, using either "phenomenons" or "phenomenas" is grounds for an automatic F in the course.  Just kidding … but do not use an "s" with either of these words.  We really mean it.


Theories are interpretations or explanations of phenomena.  For example, even if we know that there is a statistical relationship between stress and depression, we still need an explanation for this relationship.  Does the stress cause the depression?  If so, how?  Similarly, even if we know that babies begin to smile at about two months of age, we still need an explanation for this phenomenon.  Why two months as opposed to two weeks, or six months, or whatever?  What is going on inside the baby or in the baby’s environment to make this happen?

Note that in everyday usage, the word "theory" often refers to an idea that has not been tested or proved.  This is not what scientists mean.  The theory of evolution by natural selection, for example, is accepted by nearly all biologists as a reasonably accurate account of the development of life on earth.  It is a theory not because it has yet to be proved, but because it is an explanation for a large set of phenomena.  Similarly, the adjective theoretical in science means having to do with explaining or interpreting the things we observe.  If I ask you to "add some theoretical ideas" to your research paper, I am not asking you to speculate about unproved things.  I am asking you to discuss explanations for the phenomenon that you are studying.

Distinguishing Phenomena and Theories

Phenomena and theories are distinct and you must always be careful to distinguish them.  When you read textbooks and research articles, you should ask yourself what phenomenon is under study and what theories are being proposed to explain it.  When you are thinking about your own research, you should consider what phenomenon you are studying and what theories you might propose (and perhaps even test) to explain it.  The ability to distinguish phenomena and theories is a prerequisite for doing good research and communicating clearly about it. 

An extremely important principle is that for any phenomenon there are multiple plausible theories.  This is always true, yet it is a difficult idea for many students to grasp.  Imagine that we find that people who received monetary allowances as children are more financially responsible as adults.  There are many plausible explanations for this result.  One is that children who receive allowances somehow learn from experience how to handle money.  Another is that financially responsible parents are more likely to give their children allowances, and the children learn to be financially responsible by observing the parents directly.  Yet another is that children who demonstrate early that they are responsible people are more likely to be given allowances by their parents.

In many situations, there is one theory that springs immediately to most people’s minds.  For example, most people would immediately think of the learning-from-experience explanation for the allowance result.  This is nothing wrong with this except that people often confuse such intuitively plausible theories with the phenomena that they are meant to explain.  For example, once people hear that childhood allowances and financial responsibility are related, they are likely to think they heard that children who receive allowances learn from this experience to be financially responsible adults.  One problem with this is that the most intuitively plausible theory is not always correct.  A second problem is that once a person assumes that one theory is true, it becomes difficult for that person to see that there are other plausible alternatives.  Obviously, if we fail to see most of the plausible alternative theories, then our chances of having a complete explanation of our phenomenon are not very good.

It is also the case that in many situations, there are multiple correct theories. So even if you have a theory and you have some good empirical support for it, you may only have part of the explanation for your phenomenon. Consider the phenomenon of unrealistic optimism: people tend to judge themselves to be at lower risk for negative events (e.g., being hurt in a car crash) than are their peers.  Researchers have suggested various theories to explain this including  1) that people judge themselves at lower risk than others to protect their egos, 2) that people judge themselves at lower risk because they overestimate the degree to which they (compared to others) can control the events in question, 3) that people focus on themselves and fail to think sufficiently about others when making their risk judgments. At this point you will not be surprised to hear that all three of these theories appear to capture a piece of the overall puzzle. There appears to be no one reason that people exhibit unrealistic optimism. This is sometimes referred to as multiple causation: the same phenomenon has multiple contributing causes. It seems safe to say that in psychology multiple causation is the rule rather than the exception.

So it is extremely important for you two develop the ability to distinguish between phenomena and theories, and to think of as many plausible alternative theories for a given phenomenon as possible.  This ability is one of the things that sets the thinking of psychologists apart from that of most non-psychologists.  This helps to explain why psychology instructors are driven crazy by student papers that identify a phenomenon and then discuss only one theory to account for it—as opposed to comparing multiple theories.            

Theoretical Thinking

Although for every phenomenon there are multiple plausible theories—and there can even be multiple correct theories—it is not the case that any theory is as good as any other. Here we discuss the functions of theories (what they are for), which gives us some criteria for deciding whether a particular theory is a good one. Then we discuss how theories are used both to generate new research and to evaluate the theories themselves.

Functions of Theories

Theories have several functions, and different researchers and textbook authors organize them and name them somewhat differently. Here is one good way.

Understanding – A good theory gives us a deeper sense of understanding. It tells us "why," as opposed to just "what."

Organization – A good theory helps us to organize, remember, and think about a variety of phenomena.

Prediction – A good theory allows us to predict what will likely happen in new situations.

Generation of New Research – A good theory suggests new and interesting hypotheses to test, which may lead to the discovery of new phenomena and the refinement of the theory itself.

Again, you can think of these functions as criteria for judging how good a theory is. That is, better theories are those that provide more or deeper understanding, organize more phenomena, make more accurate predictions, and generate more interesting research. Another criterion, closely related to organization, is parsimony. This means simplicity. All else being equal, scientists prefer theories that are more parsimonious—that explain more phenomena using fewer concepts, as long as those concepts are consistent with other things that we know. (See characteristics of scientific explanations for more on this.)

Using Theories in Research

Here is a model of how theories are used in conducting research.  If you took Psych 10 here at CSUF, you might recognize this model as the “Cycle of Science.”  Although I think calling it the Cycle of Science is a bit overblown, it does capture some important aspects of how theories are used to generate new research, and how theories themselves are modified.

1) We observe a phenomenon or set of phenomena.

2) We propose a theory to account for the phenomena.

3) We ask ourselves, “If this theory were true, then what new observation should I be able to make?”  Our answer to this question is a prediction or hypothesis that we derive from the theory.

4) We test the hypothesis by making empirical observations (e.g., doing a correlational study or an experiment), and two things can happen …

5) A) If the hypothesis is confirmed, then we say that the theory was supported.  We feel a bit more confident in it.  It does not “prove” the theory, however, for two reasons.  First, there might always be other theories that make the same prediction.  So in a way, we have supported any theory that makes that prediction, not just ours.  Second, it might make other predictions that are incorrect; we just have not tested them yet.  Eventually, though, a theory can receive so much support that for all practical purposes it is “proved.”  B) But if the hypothesis is disconfirmed, then we say that the theory was not supported or that it was refuted.  If we have confidence in our result (i.e., we think it was not a fluke), then we discard the theory or modify it.

6) In any event, we go on to derive new hypotheses from our original or modified theory, and so on.

Note that an especially powerful version of this process involves two theories that predict different results in the same situation.  So regardless of what is observed, there is a good chance that one of the theories will be supported and the other refuted.  This is why researchers often develop two or more theories and then try to find situations in which two theories make different predictions.  They can “kill two birds with one stone.” 

The Value Placed on Theory in Psychology

In psychology, there is a very high value placed on theory. The people who become famous researchers in psychology are not so much those who discover new phenomena as those who develop new theories to account for those phenomena. It is no coincidence that the most prestigious journal in which to publish in psychology is Psychological Review, which publishes only theoretical articles. We have also found that in reviewing other researcher’s work for possible publication, and in submitting our own work, the most common criticisms are theoretical. We usually do not argue with each other’s data, but with each other’s interpretations of those data. So it is those researchers who are to generate multiple good theories and present evidence for one of them over the others who tend to be the successful.

None of this means, however, that the development and testing of theories is beyond your ability. It certainly is not. With a little practice, you should start to get the hang of it and our hope is that you will be able to demonstrate this in your final research reports.