Experimental Method in psychology

• The main and scientific method of psychology is experimental method. The method whose base is an experiment is called experimental method. Generally the sequential study or observation of any behavior or mental process under any controlled state is called the experimental method. This is clear from this definition that in experimental method the behavior is studied under controlled conditions. The study of behavior is done through variables. A Variable is any event, situation or quality of a person which is changeable. The scientific meaning of variable is any situation, incident or a quality of a person that can be measured and is quantitatively changeable. Like — age, increment, fatigue, etc. are the examples of variable, which can be measured and are quantitatively changeable.
• In any psychological experiment there are mainly three types of variables — Independent variables, Dependent variables, and Relevant or Control variables. Those variables which can be manipulated by the experimenter and whose effect can be seen on other variable is called controlled variable.
• Variable about which an experimenter wants to make any predictions after experiment is called as dependent variable. This is called as dependent variable because change takes place in this variable is completely dependent on manipulations done in independent variables.
• Generally in psychological experiments some variables are there whose effects are controlled by the experimenter. Because he don’t want to study their effect on dependent variables this type of variables are called as relevant variable or extraneous variables or controlled variables.
• We can understand the relationship between dependent variable, independent variable and controlled variable by this example. Suppose if an experimenter wants to study the effect of reinforcement on learning, then it is clear he wants to prediction about learning process by this experiment. Therefore learning is an example of dependent variable, reinforcement is an independent variable because he will make manipulations in independent variables and he will see the effect of this manipulation on dependent variable i.e. process of learning.

Merits of experimental methods are as follows:

1. In experimental methods the study of variables associated with behavior and mental processes of any organisms are done under controlled conditions (mostly in laboratories) as a result of which the conclusion contains highest internal validity. Because of this quality experimental method is different from other methods as it is not possible to have this much control on situations in other methods. Atkinson, Atkinson & Hilgard(1983) said that, ” The capacity to have precise control on variables makes experimental method different from other methods of observations.”
2. The experiment method has a quality of replication. The experimenter clearly mentions the research design, no. of subjects, manipulation in i ndependent variables, etc. So if the other experimenter has any doubts about the findings of prior experimenter than he can repeat the experiment to check the findings.
3. Experiment method is very objective because the experimenter has to use a particular method in a special way. Therefore he cannot make any bias or prejudice etc. As this technique is objective therefore the obtained data can be analyzed qualitatively and quantitatively.
4. In experiment method the manipulation of the variables can be done easily therefore the experimenter can study the psychological problem into many ways.

Demerits of experimental method:

1. The main demerit of experimental method is that the controlled situation of an experiment is not related with reality rather it is an artificial situation. Therefore it has very less connection with real life situation. Hence the generalization of conclusion obtained from experimental method is not possible. Morgan, King & Robinson (1981), expressed their views in this same way, “The conclusions obtained from experiment are only limited till artificial experimental situation and its generalization is not possible for real or natural situations in any behavior”.
2. Some special types of demerits are naturally present in an experimental method. The experimenter bias and sampling bias are two types of important biases. In the experimenter bias the result and observation process is affected by the expectations of the experimenter. The sampling bias means that the sample is not representative. Sometimes it is seen that the experimenter selects the sample according to the availability , a result of which these sample do not represent the group about which the prediction were made prior to the experiment. Sometimes it is also seen that the experimental and controlled groups are not equivalent. Therefore the results obtained do not remain much valid and reliable.
3. Some experiments can be administered on the animals only, but can’t be on humans. This results in the limitation of the scope of field study. For an example if there is any experiment in which any body part like any specific part of brain has to be removed or operated to see its effect on behavior, than it will be inhumane to do this experiment on any human and more over no human will be ready for being a subject. But it is easy to do such an experiment with animals. The results obtained after experimenting on animals can be generalized on human beings, yet there remains much possibility of errors.

Inspite of these limitations experimental method is considered as a scientific method in experimental psychology. Today there is no validity of those theories and facts which has less or no experimental support.

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Important Points :- 

1. In the present chapter methods of psychology and measure of central tendency are discussed. Invigilation method is also called as observation method. In this method the observer studies the behavior of the organism or person.
2. The case study method is used in clinical psychology to identify the symptoms of any disease and the cause responsible for it.
3. Generally the conversation between two or more persons for any specific cause is called as an interview.
   Survey method, experimental method introspection method are the basic psychological methods.
4. The measure of central tendency are- Mean, Mode, Median. In the present chapter frequency distribution, linear presentation, graphical presentation, frequency polygon and histogram are discussed.

1. The meaning of frequency is:
a) Scores
b) No. of repetitions of scores
c) Multiple of scores
d) None of these

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2. Which of the method is not suitable for absolute frequency distribution?
a) Exclusive method
b) Inclusive method
c) Exact method
d) None of these

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Answer :- D

3.) Which is the formula for range?
a) (H-L)+1
b) (H+L)-1
c) (H-L)
d) NONE OF THESE

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Answer :- A

4. The symbol of size of class interval is:
a) Y
b) X
c) i
d) p

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Answer :- C

5. Which of the following is a graphical method?
a) Frequency polygon
b) Histogram
c) Bar diagram
d) All the above
Answer :- ????