This document discusses the experimental method in psychology. It notes that Wilhelm Wundt opened the first experimental laboratory in 1879. The experimental method involves manipulating an independent variable and observing its effects on a dependent variable while controlling for extraneous variables. There are three types of experiments: laboratory experiments with strict control, field experiments with less control in natural environments, and quasi-experiments that manipulate variables without random assignment. The experimental method generally compares an experimental group exposed to the independent variable to a control group that is not exposed, to test hypotheses about causal relationships between variables. Techniques like random assignment and counterbalancing help control for extraneous variables.

1. Experimental Method
Dr Shiva Shukla
Assistant Professor,
Central University of Punjab, Bathinda

2.  Wilhelm Wundt 1879 opened first Experimental Laboratory in
University of Leipzig (Germany)
 Like any other science Behaviour Science is based on observations and
experiments which one can verify
 This method is restricted to laboratory research that investigates basic
psychological processes
 Laboratory Experiment, Field Experiment and Quasi Experiment
 Laboratory Experiment – Controlled Setting
 Field Experiment – Natural Life Conditions and control over relevant
variables is minimal
 Quasi Experiments - Independent variables are manipulated in natural
setting using naturally occurring groups to form experimental and
control groups. Applied when conditions cannot be manipulated in
laboratory situation or conditions cannot be created artificially

3. What is Experimental Method ?
 Experiment Method is investigation designed to find out causal association between two or
more variable
 Changes made by the investigator in one factor and effect is studied on another factor
 Any stimulus or event that varies or changes in value is called a variable
 Two distinct features- a) investigator manipulates independent variable also called conditions,
and b) investigator minimizes or controls the variability in extraneous variables which are
other than independent and dependent variable
 Variable which is altered or manipulated in the experiment is independent variable and
variable on which impact of independent variable is studied is called dependent variable.
Thus, independent variable is the cause and dependent variable is the effect in an experimental
situation
 Variables that have to be controlled as they might confound the effect of independent
variable are called relevant variables e.g. organismic( age, gender, personality features etc.),
situational ( physical environment: noise, pollution, temperature, humidity etc.), and sequential
( procedure of conducting the experiment)

4.  Experimental Method generally involves two or more Experimental and
Controlled Groups
 The group which is being exposed to independent variables is called
Experimental group
 Comparison group that is treated like experimental group except that
manipulated variable is absent is called Controlled Group
 Hypotheses are basis of predicting how variables connect to each other(Null
and Directional)
 Credible evidence of cause and effect relationship calls for a successful
experiment
 This method has conclusive power as results are more precise

5. Techniques to balance unwanted effect on
Relevant Variables
a)Elimination: the extraneous variables are eliminated from the
experimental surrounding
b)Making Conditions Constant: Extraneous variable that cannot be
removed are kept in constant control
c) Matching: Relevant variables in two groups are equated and kept in
constant condition throughout the experiment
d)Counter Balancing: to minimize effect of sequencing of the
experiment usually is done by dividing participants in two groups
e)Random Assignment: All participants have equal chance to get
exposure to controlled or experimental groups