In all types of research, we need to consider two closely related concepts:
hypothesis
vs. theory. An hypothesis can loosely be defined as an educated guess about some relationship or circumstance that we have observed, and the purpose of the hypothesis is to explain what we have experienced and to provide a starting point for further research. When a set of observations seems to come together, especially as the result of testing our hypotheses, we might then propose a theory to bring those observations together. However, a theory is not necessarily our end point, since the theory itself may generate new hypotheses and more research. In this way, all scientific endeavors continue to develop, expand, clarify, change, whatever the case may be, over time. As a result, we have many different personality theories, since different theorists have viewed the human condition differently, and they have also used different techniques to study personality.
A variety of methods have been used to study personality. Much of the early research was based on clinical observations, which were not done according to strict experimental methods. Today, ethical restrictions on the types of research we can conduct with people limit our ability to re-evaluate many of those classic studies. So we are left with a field that is rich in theory, but somewhat poor in the validation of those theories. Of course some personality theorists have approached personality in a more scientific manner, or at least they have tried, but that has limited the questions they have been able to ask. Since a detailed analysis of experimental psychology and research design is beyond the scope of this textbook, we will only cover this topic briefly (though it may come up again within individual chapters).
Case Studies
Many of the best-known personality theorists relied on case studies to develop their theories. Indeed, it was after seeing a number of patients with seemingly impossible neurological complaints that Freud began to seek an explanation of psychological disorders. Basically, the case study approach relies on a detailed analysis of interesting and unique individuals. Because these individuals are unique, the primary criticism of the case study approach is that its results may not generalize to other people. Of greater concern, is the possibility that early theorists chose to report only those cases that seemed to support their theories, or perhaps they only recognized those elements of a patient’s personality that fit their theory? Another problem, as mentioned above, is that two different theorists might view the same cases in very different ways. For example, since Carl Rogers worked initially with children, he found it difficult to accept Freud’s suggestions that even children were motivated primarily by sexual and aggressive urges. Consequently, Rogers sought a more positive view of personality development, which led to the establishment of the humanistic perspective. Thus, the case study approach can lead to very different conclusions depending on one’s own perspective while conducting research. In other words, it can easily be more subjective than objective, and psychologists who focus on our field as a scientific discipline always strive for more objective research.
Correlational Designs
When conducting correlational research psychologists examine the relationships that exist between variables, but they do not control those variables. The measure that is typically used is the
correlation coefficient
, which can range from –1.0 to 0.0 to +1.0. A value close to zero suggests that there is no relationship between the variables, whereas a value closer to –1.0 or +1.0 suggests a strong relationship, with the direction of the relationship determining whether the value is positive or negative. It is important to remember that the strength of the correlation is determined by how far the correlation coefficient is from zero, not whether it is positive or negative. For example, we would most likely find a positive correlation between the number of hours you study for a test and the number of correct answers you get (i.e., the more you study, the more questions you get right on the test). On the other hand, the exact same data will give us a negative correlation if we compare the number of hours you study to the number of questions you get wrong (i.e., the more you study, they fewer questions you get wrong). So the way in which you ask the question can determine whether you have a positive or negative correlation, but it should not affect the strength of the relationship.
Since the investigator does not control the variables in correlational research, it is not possible to determine whether or not one variable causes the relationship. In the example used above, it certainly seems that studying more would lead to getting a better grade on a test. But consider another example: can money buy happiness? There is some evidence that wealthy people are happier than the average person, and that people in wealthy countries are happier than those in poorer countries. But does the money affect happiness? Certainly a million dollars in cash wouldn’t help much if you were stranded on a desert island, so what can it do for you at home? People with money can live in nicer, safer communities, they have access to better health care (so they may feel better physically), they may have more time to spend with their family and friends, and so in many ways their lives might be different. We can also look at the correlation the other way around; maybe happy people get more money. If you ran a company, and were going to hire or promote someone, wouldn’t you want to find someone who is friendly and outgoing? Wouldn’t you look for someone who other people will enjoy working with? So, maybe happy people do find it easier to be successful financially. Either way, we simply can’t be sure about which variable influences the other, or even if they influence each other at all. In order to do that, we must pursue experimental research.
Figure
\(\PageIndex{1}\)
In these figures, adapted from research conducted by the author (Kelland et al., 1989), we see two correlations reported in an actual study. In the figure on the left, we can see a significant positive correlation between the firing rate of dopamine neurons in the rat brain and the dose of the drug quinpirole needed to inhibit those cells. In the figure on the right, we can see that the correlation is eliminated (the dose of quinpirole needed is not related to the firing rate of the cell) following administration of the drug MDMA (more commonly known as Ecstasy!).
Experimental and Quasi-Experimental Designs
The experimental design is usually preferred within psychology, as with any other science. The goal is to control every aspect of the experiment and then manipulate a single variable, thus allowing us to attribute the results to that single manipulation. As a result, experiments allow us to make cause-and-effect statements about the relationships between the variables.
A simple experiment begins with defining the
independent variable
, the factor that will be manipulated, and the
dependent variable
, the factor that will be measured. Ideally, we then select our subjects in a random fashion, and assign them randomly to a
control
group
and an
experimental group
. The experimental group is then exposed to the independent variable, whereas the control group is not. If we have successfully controlled all other variables through random selection of subjects (i.e., all subjects in a specified population have an equal chance of being selected for the study) and random assignment to the control and experimental groups (so that hopefully each group has an equal representation of gender, races, age, intelligence, personal habits, etc.), we should see a difference in the dependent variable that was caused by the independent variable.
Unlike the natural sciences, however, we can seldom control human behavior in the precise ways that true experimental designs require. For example, if we want to study the effects of prenatal exposure to cocaine on personality development, we certainly cannot ask pregnant women to use cocaine. Unfortunately, there are pregnant women who abuse cocaine and other illegal drugs. Therefore, we can try to identify those women, and subsequently study the development of their children. Since a variety of other factors led these women to abuse illegal drugs, we lose the control that is desired in an experiment. Such studies are called quasi-experimental, because they are set up as if we did an experiment, and can be analyzed in similar ways. The quasi-experimental approach has many applications, and can provide valuable information not available otherwise, so long as the investigators keep in mind the limitations of the technique (for the classic discussion of this design see Campbell & Stanley, 1963).
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Table \(\PageIndex{1}\): Research Designs in the Study of Personality
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Case Studies
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Focus is on a detailed examination of unique and interesting cases. May provide a great deal of information, but due to the individual nature of the case that information may not generalize to others.
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Correlational Designs
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Focus is on how variables change in relation to each other. However, since there is no control over that change, we cannot determine whether one variable affects the other, or vice versa, or even if the change is due to some unidentified outside factor.
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Experiments
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Experiments are usually the preferred type of research, since the control exerted over the variables involved allows the investigator to make cause-and-effect statements about the results obtained. However, ethical considerations often make experimental research with humans unacceptable.
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Quasi-Experiments
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When individuals choose to put themselves in situations that psychologists could not ethically create, a situation arises in which the consequences can be studied as if an experiment was done. These are not true experiments, however, since the investigator cannot be sure of all the variables that led the individuals to put themselves in such situations to begin with.
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Cross-Cultural and Multicultural Research
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In an effort to control the conditions of their research, psychologists try to work with clearly defined groups. Unfortunately, that means their results may not generalize to other groups of people. Cross-cultural and multicultural psychologists remind us that, in a truly global world, we must strive to address both the differences and the similarities that characterize human nature.
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Cross-Cultural Approaches to the Study of Personality
Cross-cultural approaches to studying personality do not really represent a different type of research, but rather an approach to research that does not assume all people are influenced equally by the same factors. More importantly, cross-cultural psychologists recognize that seemingly common factors may, in reality, be quite different when viewed by people of very different cultures. The most obvious problem that arises when considering these issues is the potential difference between cross-cultural and multicultural research. Cross-cultural research is based on a comparison of cultures; two well-known categorizations are Eastern vs. Western perspectives and the somewhat related topic of individualistic vs. collectivistic cultures. However, a multicultural approach tells us that we must consider the true complexity of the human race. What is “Eastern,” is it Asia, China, Japan, does it include India, and what about Muslim groups of people? Should Buddhism be viewed as an Eastern perspective or a religious perspective? This book will address a variety of spiritual paths toward positive psychological development, but none of the associated religions are indigenous to Africa, so will our discussions be complete? The list goes on and on, because there are so many different cultures in the world. And finally, is it practical to really try coming up with a theory of personality that can encompass all the different groups of people throughout the world? Only by pursuing an understanding of different cultures can psychology truly be considered a global science, and that pursuit has only just begun. Since we have a long way to go, the future is ripe for new students to pursue careers in psychology and the study of personality.
Discussion Question:
Do you consider psychology to be a science? Has psychology successfully applied the scientific method to the study of mind and behavior, particularly the study of personality and personality development?