Methods of Psychology: Experimental

Method: Meaning and Definition

Meaning - A procedure or process for attaining an object or objective.

Definition - Method is a systematic process or procedure in order to deal with some issue.

What is an Experiment?

          A scientific procedure where independent variables are manipulated, extraneous variables are controlled in order to establish or test cause-&-effect relationship between independent and dependent variables.

Cause – The event being changed or manipulated.

Effect – The behaviour that changes because of the manipulation (NCERT).

Major components of an Experiment

          Variables are the major components of an experiment where a researcher tries to establish cause-effect relationship between two or more variables.

Variable – Anything (attributes of which) which can vary or that can have different values and can be measured. For example intelligence, learning, motivation etc.

Major type of Variables

          Variables are of various types few of them are described below: -

          (i)       Independent Variables – Variables that are expected to cause some           significant effect/change in dependent variable.

          (ii)      Dependent Variables – Variables that are expected to be affected by           independent variables.

          E.g. - Research Statement

          “Does level of intelligence affects the academic achievement?

          In this case   

          IV – Intelligence

          DV – Academic Achievement

          (iii)     Extraneous Variables – The variables which are not being studies but     significantly influences the results. They are also called as ‘Plausible causes’.

          E.g. – Research statement “Memory significantly affects individual’s academic      achievements”. Here, the ‘intelligence’ is one of the extraneous variables which       can influence the results. 

          (iv)     Confounding Variables – Variables that influences IV & DV and           consequently produce unexpected outcomes.  

          E.g. – Research statement “Good opportunities ensures good academic           achievements”

          Here, ‘hard work’ on the part of the subject can effects availability of           opportunities (IV), academic achievements (DV) and results.

          (v)      Intervening/mediating Variables – The unseen variables that causes           the change in DV instead of IV.

          E.g. – Research statement “The intensity of light improves the academic           grades”

          Here, in fact the academic grades are influenced by ‘intelligence’           (Intervening/mediating variable) and other variables whereas researcher thinks           otherwise.

          (vi)     Organismic Variables – The biological characteristics of the subject           used for grouping are known as organismic variables.

          E.g. Research statement “Girls have high level of empathy”

          Here, ‘gender’ (girls) is the organismic variable.

          (vii)    Dummy Variables – A dichotomous variable that can take only two           values and represent categorical data. E.g. gender, residential status           (urban/rural), attitude towards life (Optimistic/pessimistic), binary numbers etc.

Minimum Requirements of a Scientific Experiment

          An experiment is said to be scientific when it fulfils the following conditions: -

(i)       Control of extraneous variables.

(ii)      Randomization in sampling, group formation and administration of intervention techniques.

(iii)     Homogeneity & representativeness of sample.

(iv)     Control of biases including Experimenter Expectancy Effect.

(v)      Pre-tested (through pilot study) experimental design.

Structure of an Experiment

          An experiment must have minimum one ‘Experimental group’ and one ‘Control group’.

(i)       Experimental Group – The group in which the subjects are exposed to manipulated IVs.

(ii)      Control Group – It’s a comparison group and treated and exposed to all similar conditions as experimental group except manipulated IVs. Various techniques are used to control the effect of extraneous variables on the dependent variable. These techniques help in filtering out the effects other than IV in other words it improving the purity of IV effect.

          (i)       Elimination of Extraneous Variables.

(ii)      Keeping Extraneous Variables constants (When elimination is not feasible).

(iii)     Matching (especially for Organismic (intelligence) and Background Variables (rural/urban or SES).

(iv)     Counter-balancing (to minimize the sequence effect).

(v)      Randomization.

Limitations of an Experiment

          Despite following highly scientific methodology, an experiment suffers from various following limitations.

1.       Most experiments are conducted in laboratory under controlled conditions therefore results of such experiments are difficult to generalize. They tend to suffer from External Validity.

2.       Due to the typical nature of problems they cannot be studied in the laboratory such as ‘flood’s immediate effect on cognitive abilities of the victims’.

3.       In some situations control and manipulation of variables is not possible especially in post hoc studies (PTSD related studies).

4.       In reality it is almost impossible to control all variables.

5.       Though it establishes cause-&-effect relationship but fails to explain ‘Why’ it occurred.

Reference:

1.       NCERT, Class XI Psychology Text book.

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