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Research Methods
Lesson 04: Experimental Methods
Not to be confused with Lesson 02: Experimental Design
Prep Work Check Please have your completed prep work ready
for checking, including:
Task 6: 1. Underline the IV; 2. Circle the DV; 3. Decide whether the following are directional or non-directional hypotheses.
Your Tedious Links – Using the following key terms…Key words: Aim, Research
Question, IV, DV, Hypothesis, One-tailed, Two-tailed, Target Population, Sample, Random,
Opportunity, Volunteer
Types of Experiment
1) Laboratory Experiments
2) Field Experiments
3) Natural Experiments (Quasi-experiments)
Laboratory Experiments A laboratory experiment is a controlled
situation in which the researcher manipulates one variable to measure its effect on another.
Strengths & Weaknesses… Task 1: Decide whether the following points
are strengths/weaknesses of laboratory experiments and write the answers in your exercise books…
In a lab it’s easy to control the independent variable.
The experiment can be
replicated at any time
in the future.
All other variables
can be “held
constant”
May lack ecological validity -
(This means what happens in
the lab may not be true to
life.)
Some situations simply
cannot be created in lab
conditions. (Suppose we
want to study why people
commit suicide )
Types of Experiments
1) Laboratory Experiments
2) Field Experiments
3) Natural Experiments (Quasi-experiments)
Field Experiments Take place outside a laboratory, in a natural
setting. However, the basic scientific procedures are still followed:
The Independent Variable is manipulated;
To measure the effect on the Dependent variable.
However, they don’t have to be in a field – in fact they could even be underground !
The Subway Samaritan Task 2: Read “Example 1: The Subway
Samaritan” and answer the three questions at the bottom of page one, in your exercise books.
The Subway Samaritan (Part 1) The researchers arranged for a passenger to
fall over on the New York subway, travelling on a long section – more than 7 minutes.
Aim: The aim was to investigate which factors led people to help someone in difficulty.
The Subway Samaritan (Part 2) Method: The passengers who witnessed this
event were really the participants, they just didn’t realise it. Students sitting among them would be the observers.
Results: If the man who fell over was holding a walking stick he got helped 95% of the time; If he was holding a bottle of whisky less people tried to help – only 50% of the time; Women were much less likely to help the person with the whiskey; The person with whiskey was much more likely to get help from his own ethnic group.
What makes this an experiment?
1. Was there an independent variable being manipulated? If so, what is it?
2. What was the dependent variable?
3. What Experimental Design was used - Independent Measures, Repeated Measures or Matched Pairs?
The condition of the man who fell over (walking stick vs. whiskey bottle).
The % (or number of) passengers who assisted/helped the man who fell over.
Independent Measures.
Reality TV & Field Experiments Reality TV is full of “Field-Experiments”
In fact several top shows have taken their ideas from long-standing psychology experiments.
Can you think of any shows where people are put in a situation which is manipulated ?
Big Brother…
Love Island
Dating in the Dark…
Strengths & Weaknesses… Task 3: Use the following key terms to
evaluate field studies:
Ecological validity
Participant reactivity
Extraneous variables
Time
Deception
Are the above bullet points potential strengths or weaknesses of field studies.
Key Point A field experiment is still an experiment
because of one on essential feature. Can you explain what that feature is ?
Remember, our definition of an experiment: An experiment is a controlled situation in which the researcher manipulates one variable to measure its effect on another.
The psychologist still manipulates the independent variable.
Other Types of Experiments
1) Laboratory Experiments
2) Field Experiments
3) Natural Experiments (Quasi-experiments)
The Winter War Task 4: Read “Example 2 – The Winter War”
and then answer the two questions in your exercise books.
The Winter War (Part 1) In 1939 Finland was invaded by Russia.
The Finns fought with immense courage but were eventually over-run.
The Winter War (Part 2) Psychologists later found that women who
had been pregnant when their husbands were killed were more likely to have babies who grew up to be schizophrenic.
It has been suggested that stress on the mother in the middle stage of pregnancy may cause schizophrenia.
The Winter War1. What was the I.V. in the Winter War
‘experiment’:
2. How did the psychologists manipulate the independent variable ?
Pregnant women who lost their husbands vs. pregnant women who did not lose their husbands.
They didn’t manipulate the I.V. – It occurred naturally.
Natural Experiments In a natural experiment the researcher
makes use of naturally occurring variables.
These are not true experiments because the scientist cannot really manipulate the IV.
Sometimes referred to as a “Quasi-Experiment”
What does Quasi mean ?
It means something is not quite real.
It may work like the real thing, but it’s not the real thing.
Real Money Quasi Money
Strengths & WeaknessesAdvantages
Allows you to research with groups like drug users, alcoholics, victims of abuse, without creating situations which are harmful to the participants.
High level of ecological validity.
Disadvantages
High level of extraneous variables;
Difficult to replicate.
Mix & Match… Task 5: The columns of your Experimental
Method table have been mixed-up.
Match up the type of Experimental Method with each of the key features, by highlighting or colouring each experimental method in a different colour…
Mix & Match – The Answers… Your table should look like this:
04 Mix & Match Answers.pdf
Applying Experimental Methods
Task 6: For each of the following research questions (see your hand-out), consider which Experimental Method you would use (lab, field, or natural experiment) and why?
Furthermore, consider which Experimental Design you would use (Independent Measures, Matched Pairs or Repeated Measures) and why?
Your MUST be able to justify your answers…
Which design would you use?1. You wish to study how changes in lighting, heating and breaks affect the productivity of workers.
Would you use:
A Laboratory experiment
A field experiment
A Natural experiment
Which design would you choose from:
The independent measures design
The matched pairs design
The repeated measures design
Which design would you use?2. You wish to study how parents in Essex bring up their children.
Would you use:
A Laboratory experiment
A Field experiment
A Natural experiment
Which design would you choose from:
The Independent Measures design
The Matched Pairs design
The Repeated Measures design
Which design would you use3. You wish to study how aggressive behaviour on television affects the behaviour of viewers.
Would you use:
A Laboratory experiment
A Field experiment
A Natural experiment
Which design would you choose from:
The Independent Measures design
The Matched Pairs design
The Repeated Measures design
Which design would you use?4. You wish to study how girls in Essex behave towards someone when they have a romantic interest in them.
Would you use:
A Laboratory experiment
A Field experiment
A Natural experiment
Which design would you choose from:
The Independent Measures design
The Matched Pairs design
The Repeated Measures design
Which design would you use?5. You wish to study at what age babies can recognise a human face.
Would you use:
A Laboratory experiment
A Field experiment
A Natural experiment
Which design would you choose from:
The Independent Measures design
The Matched Pairs design
The Repeated Measures design
Which design would you use?6. You wish to study whether some teachers are better than others.
Would you use:
A Laboratory experiment
A Field experiment
A Natural experiment
Which design would you choose from:
The Independent Measures design
The Matched Pairs design
The Repeated Measures design
Which design would you use?7. You wish to study whether people really get better as a result of psychotherapy sessions.
Would you use:
A Laboratory experiment
A Field experiment
A Natural experiment
Which design would you choose from:
The Independent Measures design
The Matched Pairs design
The Repeated Measures design
Which design would you use8. You wish to study whether there are measurable differences in the personalities of men and women.
Would you use:
A Laboratory experiment
A Field experiment
A Natural experiment
Which design would you choose from:
The Independent Measures design
The Matched Pairs design
The Repeated Measures design
Extension Activities…Which type of experiment would be best for investigating the following hypotheses:
Duration of memory will be longer if the words rhyme.
Most people are too shy to complain about being short-changed.
Too much day care makes children aggressive.
Maternal deprivation causes children to become affectionless psychopaths.
When a small child is lost in the street, women are more likely to help than men.
Chimpanzees can learn to communicate with sign language.
Homework Task 7: Homework (See Handout)
Your task is to answer the following five questions, in relation to the four scenarios below, in your pink exercise books. Due: Next RM lesson.
Plenary…RANK THEM
WRITE down 5 things that you have learnt about the topic (Research Methods) so far.
Which is the most important, TELL ME WHY…What is least?
Most
Least
