experimental method

What is Experimental Method? Definition, Process, Merits, and Demerits

Experimental Method: Cause and Effect Relationship

The most scientific method to bring psychology to the level of exact science is the experimental method. Under this method, variables are experimented with in the laboratories and through other controlled methods to find out their cause and effect relationship.

Wilhelm Wundt was the pioneer in this field. He established the first psychological laboratory in Leipzig University, Germany 1879. Therefore he regarded as the “father of experimental psychology“. Also, William James and Ruch (1970) are the contributors to this method.

In this method, the experiments or research take place in special laboratories under artificially controlled conditions. It commonly requires special equipment and apparatus that is a property set up in a fixed place which can be easily used by different scientists.

In the experimental method, all factors are kept constant and only one factor is varied at a time to determine the effect of this variable on the problem of the study to find out the cause and effect relationship between the two or more variables. Thus, the experimental method requires a well-planned and facilitated laboratory, apparatus, and equipment, subject and experimenter, problems, objectives, hypothesis, and design to process and proceed toward the scientific exploration.

Process of Experimental Method

A well planned experimental design needs to follow a series of steps. They are:

1. Raising A Problem

The first step in the experimental method is raising a problem or simply say finding a problem. In everyday life, many factors influence our behavior. Sometimes we are puzzled and ask questions to ourselves as to why people act as they do. These inquiries lead us to raise problems before us.

For example, why do people smoke? Why motivation influence study? What effects does Marijuana bring in recall? What affects intelligence? Experiments can help find answers to these questions. Experiments start with a problem, without its presence there is no question for experimentation. It explores to find the solution.

2. Formation of A Hypothesis

In the second step, the problem is forwarded in the form of a hypothesis. Hypotheses are the assumptions made to test the problem. It may be formulated positively or negatively on the basis of available literature in the area. The hypothesis may be proved or disproved by the results of the experiment.

In the example of motivation, the hypothesis may be “motivation enhances performance”. Similarly, on the problem of smoking, the hypothesis may be “smoking is harmful to physical and mental capacity”. These testable predictions enable us to test, reject, or revise the theory.

3. Distinguish Between Dependent and Independent Variable

A variable is an event or condition which can have different values. It can be measured and varies quantitively. While organizing the experiment the experimenter decides between the dependent and independent variable. The independent variable is the stimulus variable which he wants to study to finds the effects of its change on the performance.

The factor in any experiment which the experimenter chooses to manipulate to examine its effect upon the result is known as the independent variable. The dependent variable is the response that the experimenter intends to find out so, they are the effect. In the example of motivation, motivation is the independent variable and performance is the dependent variable.

4. Controlling The Environment or The Situation

While experimenting, the experimenter needs to control the extraneous variables that negatively influence the experiment. This helps us focus on relevant aspects of the experiment and eliminate the irrelevant aspects. For this, the experiments are divided into two groups controlled and experimental groups to compare the results.

5. Analysis of The Result

The scientific inquiry requires results to be analyzed properly by comparing the controlled condition i.e. the dependent variable and experimental condition, i.e. the independent variable with each other. This is done through statistical procedures appropriate for that experimental design.

Taking the example of marijuana again, the experimental can use tables and graphs to present his findings to enhance the understanding and knowledge about the subject matter and again to compare with the previous findings of the area.

6. Verification of the Hypothesis by the Result of the Experiment

This is the last step in the process of the experimental method. After analyzing the results it is necessary to verify the assumptions made in the experiment, whether the hypothesis is proved or disproved. Usually, if the hypothesis is proved, it will add positivism and strength, enhancing the theoretical aspect of the prevailing literature but if goes the opposite, it creates doubt and confusion in the subject matter making grounds for further more researchers.

Limitations and Advantages of Experimental Method

Limitations or Disadvantages of the Experimental Method

Artificial Situation of The Laboratory

The environment of the laboratory condition is artificially made and designed which may not provide the same result obtained under natural surroundings, hampering the purpose of the experiment. The experimental arrangement and setup require a well-equipped laboratory which makes it quite expensive and unreachable to interested people. The subject may feel observed, nervous, and as result neglect, certain behavior which crates the doubtful data.

Difficult in Attaining Cooperation, and Attitude of the Subject

For example, an experimenter wants to study the reaction during the injection. The subject thinks that it will be bad if he shows negative gestures, so he laughs while being injected, making the whole experiment fake. While doing the experiments it is necessary to control the attitude of the subject and get his cooperation. Without the cooperation of the subject, the experiment will be impossible and the data obtained will be wrong.

Experimenter Effects

Not only does the attitude of the subject influence the experiment, but the experimenter’s attitude itself may also unknowingly hamper the whole experiment. The experimenter’s behaviors, characteristics, and expectations may influence the outcome of his research without his knowledge. These influences are referred to as experimenter bias or experimenter effects.

Limited Field

Another limitation is that the experimental method is restricted in its application. The experimental method does not involve examining different social issues and the behaviors of crowds, children, abnormal persons, etc.

Advantages of Experimental Method

In spite of the limitations involved in the experimental method, in many ways it is the best valuable technique for collecting scientific information in psychology. There are certain basic advantages of this method over other methods.

Testing Casual Relationship

Through the logic and control of the experiment, it is possible to test the hypothesis of casual relationships which is the primary advantage of formal experiment over other scientific methods.


Another important advantage is replication. The experiment can be repeated if the experiment is performed under proper conditions. Experimental findings which can not be repeated generally do not become a part of scientific knowledge and will not be accepted by other scientists. This is possible with the experimental method. The replication of check-up-ability makes the result reliable which is an essential part of the experimental method.

Control The Environment

Since unnecessary and irrelevant factors or variables are controlled, the experimental method is undoubtedly the most valuable and systematic method, making the results and conclusions of the experiments logically defined and scientific.

These merits make the experimental method more accurate to draw scientific conclusions. It has gained great value. New tools and inventions have made it more valuable in the recent world.

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