Course Title: Introduction to Psychology
Assignment No: 1
Program : BSCM
Section : F-19
Submitted to:
Miss Sehrish Munir
Submitted by:
Ayesha Hamid L1F17BSCM0024
HOW IS AN EXPERIMENT PERFORMED?
Experiment:
A scientific procedure undertaken to make a discovery, test a hypothesis, or demonstrate a
known fact.
To confirm or disconfirm a hypothesis we do experiments. To perform an experiment we would
do tee following.
1. Vary a condition that might affect behavior.
2. Create two or more groups.
3. Record the results
Example: 1
Suppose we want to find out that using cell phones while driving may have any effect on the
driving or not. For that purpose we make two groups. We will allow the first group to drive while
using phone and the second group to drive without using phone. And then determine the results
whether using mobile phone affect the likelihood of driving.
The simplest psychological experiment is based on two groups.
Experimental group: The independent variable is changed in the experimental group.
The values of the independent variable and the impact on the dependent variable are
recorded.
Control group: The independent variable is "controlled" or held constant in the control
group. This group includes individuals who are very similar in many ways to the
individuals who are receiving the treatment, in terms of age, gender, race or other factors.
VARIABLES AND GROUPS:
A variable is a condition that can change and might affect the outcome of an experiment.
Types of variables:
Independent variable: It is the variable that is controlled and manipulated by the
experimenter and is assumed to have a direct effect on the dependent variable.
For example, in an experiment on the impact of using mobile phone on driving, mobile
phone would be the independent variable.
Dependent variable: The dependent variable is the variable being tested and measured
in an experiment, and is 'dependent' on the independent variable.
For example, the driving ability of a person would be the dependent variable.
Extraneous variable: A variable that may have an impact on the relationship between
the independent and dependent variables.
For example, the extraneous variables is the driving experience and the familiarity with
the vehicle used in the experiment.
Example: 2
Let’s examine another simple experiment. Suppose you notice that you study better while
listening to music. This hypothesis state that listening to music improves learning. We could test
this by forming experimental group that studies with music and control group that studies
without music. If the score of experimental group is higher than that of control group, we can
conclude that music improves learning but if there is no difference, it’s obvious that independent
variable had no effect on leaning.
EXPERIMENTAL CONTROL:
To avoid the chance of having intelligent people in one group only, can be controlled by
randomly assigning people to groups. Random assignment means that a participant has an equal
chance of being in either experimental or control group. This would result in a few average
differences in the number of people in each group who are man or men, geniuses or dunces,
hungry, tall, music lovers or whatever.
Other extraneous, or outside variables such as the amount of study time, time of the day, amount
of light must be prevented must be prevented from affecting the outcome of an experiment.
CAUSE AND EFFECT:
Now let’s summarize. In an experiment, two groups are exposed to different levels of
independent variable. The effect of independent variable on some behavior is then measured. In a
carefully controlled experiment, the independent variable is the only possible cause for any effect
noted in the dependent variable. This allows clear cause and effect connections to the identified.
EVALUATING RESULTS:
We can conclude that an independent variable made a difference by performing experiments
more than thrice. If we get the same results then we can say that the “results are statistically
significant”.
WHAT IS DOUBLE BLIND EXPERIMENT?
Definition: Double-blind studies are particularly useful for preventing bias due to demand
characteristics or the placebo effect.
Example:
Suppose a researcher hypothesizes that a drug amphetamine improves learning. So she made two
groups, experimental group and control group and gives experimental group a pill before
studying and control group members get nothing. Later she identified that the experiment
seriously flawed for several reasons. Because the drug wasn’t the only difference between in the
groups and the people of experimental group likely expected to learn more and not the actual
result of the drug.
RESEARCH PARTICIPANT BIAS:
In a well designed experiment, you must be careful about what you tell to the participants. This
can be done by doing an experiment in which experimental group swallowed a pill and control
participants did not. This is a form of research participant bias. It could be that the persons who
swallowed a pill expected to do better. As we know that pills are also medicines so it created a
placebo effect (changes in behavior caused by behavior that one has taken a drug).
For example: A saline injection is 70% as effective as morphine in reducing pain. That’s why
doctors sometimes prescribe placebos especially for complaints that seem to have to physical
bias.
CONTROLLING RESEARCH PARTICOIPANT BIAS:
We can avoid research participant bias by using single blind experiment. In this case, participants
don’t know whether they are in the experimental group or control group or whether they are
receiving a drug or placebo because they are blind as to the hypothesis. People in the
experimental group would be given a drug and those in the control group given a placebo, but
their expectations are the same. Any difference in their behavior must be caused by the drug.
RESEARCHER BIAS:
As we noted earlier, when the experimenter explained her hypothesis to the people, she likely
biased the results of the study. But if a researcher uses single blind experiment to avoid biasing
participants’ researcher bias (changes in behavior caused by unintended influence of a
researcher) remains a problem.
For example: In an experiment, 100 airmen were randomly assigned to five different math
classes and their teachers didn’t know about this random placement. Instead they were told that
their student had low or high ability. So the teachers expected more or less from their students
through their voice tone, body language etc. Their hints in return created a self prophecy that
affected the students.
DOUBLE BLIND EXPERIMENT:
In this experiment, neither participants nor researchers know which is the experimental group or
the control group, included who received a drug and who took a placebo. This not only avoids
research participant bias but also keeps researcher unconsciously influencing participants. This
experiment can be done by hiring assistants which are blinded too and they would not know
which is the experimental group and the control group.
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