From Research Methods in Psychology

Introduction= The figure below shows a diagrammatic representation of the theory testing process. At the top, is the theoretical level – when we start we have a theory. We want to test a theory, but a theory is a very big thing to test in one go, so instead of testing a theory, we test a hypothesis derived from that theory. In the example we used in the last section we had a theory that ‘Depressant drugs effect motor skill performance,’ For any theory, there are many hypotheses that can be tested. A hypothesis is a statement about the relations between the variables. For every hypothesis, especially in psychology, there are many ways of defining and measuring the variables, which are mentioned in the hypothesis.

The hypotheses which are tested either provide support for the theory, or they disprove the theory. (Remember the theory cannot be proved, only supported.) If the theory is wrong, it needs to be either rejected completely, or modified. The support of modification of the theory is represented by the arrow showing the hypothesis feeding back to the theory.

[edit] Why use this method?

The hypothetico-deductive method is now the main method that is used in psychology, however the use of this method is comparatively recent. Can you think of any studies or theories that did not use the hypothetico-deductive method, and may have been improved if they had used this method?

Answers:

There are many theories from the history of psychology where people tried to prove that their theories were correct, instead of trying to prove that their theories were wrong. We will consider some examples that you may have encountered already in your studies. If you are unfamiliar with these studies, you will find them in any introductory psychology textbook

Piaget’s studies of cognitive development in children: Jean Piaget was a Swiss psychologist who studied the development of thinking in children. He suggested that children were able to carry out certain cognitive tasks only after they reached certain ages. In particular, he thought that children below the age of about 7 were unable to think about abstract things (things which are not here and now). He showed to his own satisfaction that children under 7 were incapable of certain tasks.

However more recent studies have found that children are more capable of abstract thought than was previously considered possible. Piaget was trying to show that children could not do something, and so designed experiments to demonstrate how incapable they were. He was using the inductive method, finding one example after another of children being incapable of doing particular tasks. More recent experiments were designed to try to find out just what children could do; they tried to show that the Piaget’s theory was wrong (or at least that it was in need of modification), and these experimenters managed to find some circumstances in which children could be persuaded to think about abstract things. They used the hypothetico-deductive method to find some evidence that could not be accounted for by the theory.

Freud’s Theories of Personality and Psychopathology: In the later 19th century and first half of the 20th century Sigmund Freud developed a theory of personality and psychopathology. He developed his ideas from the information patients gave him in therapy sessions. Freud attempted to develop a theory that could explain why the patients had the thoughts and feelings that they did. However, he did not develop this theory in such a way that it gave rise to testable hypotheses. This means that it is difficult (or impossible) to prove that the theory is untrue. For example, one of Freud’s theories suggests that if your father behaved in an oppressive manner towards you, you might respond by identifying with your father and therefore loving him. The theory also suggests that, on the other hand, you might end up hating him. Freud’s theory can explain any result, love or hate, and so either outcome is explained his theory and no outcome disproves it. The hypothetico-deductive method requires a statement which is testable - one outcome supports it, another outcome disproves it.. In fact, it is very difficult to apply the hypothetico-deductive method to Freud's theory, because Freud’s theory does not give rise to testable hypotheses.

[edit] Summary

A theory is used to develop hypotheses. Each hypothesis can be operationalised in many different ways, using different variables. The hypotheses are then tested, and used to modify the theory. This cycle of testing and modifying theories is known as the hypothetico-deductive method.