1. Hypotheses and Variables
L.O.
Understand the different types of hypotheses and the different variables found in psychological research
To apply that understanding

2. Does caffeine have an effect on reaction time?
Aims and Hypotheses
By defining the variables that we will use to test our theory we derive at our Hypothesis, which is a testable form of a theory. Testing the hypothesis is thus our Aim (it’s that simple!)
Does caffeine have an effect on reaction time?
(IV) (DV)
Null Hypothesis: Predicting that there will be no effect.
Directional Hypothesis (aka 1-tailed): Predicting an affect of the IV on the DV in a particular direction.
Non-Directional Hypothesis (aka 2-tailed): Predicting an affect but with no particular direction .

3. Aim: To investigate whether caffeine keeps you awake at night
Amount of caffeine will have no impact on the amount of sleep
Amount of caffeine will have an impact on the amount of sleep
Higher amount of caffeine will lead to decreased amount of sleep

4. The Experimental Method
The most scientific Research Method.
Main problem with all the non-experimental methods is lack of control over situation.
An experiment is a study of cause and effect.
Involves the deliberate manipulation of one variable, while trying to keep all other variables constant.

5. VARIABLES
Variables: A variable is any factor, trait, or condition that can exist in differing amounts:
- Independent Variable (IV) - the variable that is manipulated by the experimenter (input variable) to impact on the DV.
- Dependent Variable (DV) - the outcome variable (results of the experiment), that is changed by the IV.
- Extraneous variables (Ex Vs) - Other variables that might affect the DV. They might be important enough to provide alternative explanations for the effects, for example, Confounding Variables.

6. Variables and the Experimental Method

7. Number of words recalled
Independent Variable
Caffeine
influences
Dependent Variable
Number of words recalled
Time of day
2 Conditions
Tea/
Coffee
Extraneous
Variables
Noise

8. Number of words recalled
Independent Variable
Caffeine
influences
Dependent Variable
Number of words recalled
Time of day
Confounding
Variable
Tea/
Coffee
Extraneous
Variables
Noise

9. Psychologists try to control extraneous variables so that they don’t become confounding variables.
This means experiments can show cause and effect.

10. No caffeine drinks for 12 hours previously Quiet environment used
Independent Variable
Caffeine
influences
Dependent Variable
Number of words recalled
Time of day
All tested at 9 am
No caffeine drinks for 12 hours previously
These are
controls
Tea/
Coffee
Quiet environment used
Noise

11. Operationalising Variables
Many concepts in psychology are fairly abstract and difficult to
measure directly, e.g. cannot directly measure short-term
memory capacity. We can however measure the number of items
immediately recalled. Turning a variable into something that
can be measured is called ‘operationalising the variable’.
How can we operationalise:
- Intelligence?
- Aggression?
- Stress?
- Reading ability?

12. Types of Experiments (Experimental METHOD) Laboratory, Field and Natural [The ‘Control’ vs. ‘Generalisation’ Compromise] L.O: Outline and evaluate the different types of experimental methods found in research

13. Laboratory Experiments
Under tightly controlled conditions –to minimise the effects of confounding variables- an independent variable is manipulated to see the effect on a dependent variable.
Strengths
Tighter control – easier to
comment on causality.
Relatively easy to replicate.
Enable use of complex
equipment.
Often cheaper and less time-
consuming than other methods.
Weaknesses
Artificial environment; may have
low ecological validity - difficult
to generalise to other situations.
Demand characteristics;
participants may alter behaviour.

14. Field Experiments Strengths Weaknesses
Conducted in the everyday (i.e. ‘real’) environment of the participants but the situations are still artificially set up.
They are experiments; the independent variable is manipulated by the researcher; some confounding variables control might be attempted.
Strengths
People may behave more
naturally than in laboratory –
Ecological validity
Easier to generalise from
results (to similar contexts).
Weaknesses
Less control of extraneous
variables – more difficult to replicate.
Can be time-consuming
and costly.

15. Natural Experiments Strengths Weaknesses
Examining behaviour in their natural, un-manipulated environment; thus not a ‘true experiment’.
Researchers make use of an existing situation and record peoples reactions to them. Often involves observation & ‘counting’ behaviours.
Strengths
High Ecological validity.
Offer ideas for further research.
Can investigates effects of IVs
that are unethical to manipulate.
Weaknesses
IV not controlled by researcher;
little/no control in general.
Observer Effect (solutions?)
Experimenter bias; especially
since observed behaviours must be
operationally defined.

16. Experimental Method Recap
Control
Ecological Validity
Laboratory Experiments
Field
Experiments
Natural Experiments

17. Observational Techniques
Sampling: can’t record everything that every person does;  
researchers seek a representative sample of behaviour:
Time sampling: Record what the person is doing at
regular intervals of time.
Event sampling: Record every instance of the behaviour
or event of interest and their frequency.
Situation sampling: Observe behaviour in more than one
situation. This enhances the external validity of the study.

18. Observation & Use of Content Analysis!
A frequency analysis of the number of times certain
behaviours occur.
Process of Analysis:
- Sampling: The researcher must first decide Who to observe and How (as per previous slide).
- Pilot: Before actual analysis the researcher must become familiar with the types behaviours likely to be encountered.
- Framework: Deciding on the ‘Behavioural Categories’ to construct a system for recording the data.
- Procedure: Record the occurrences of behavioural categories.

19. Observational Method
Strengths
Weaknesses
Structured (Controlled): watching behaviour within controlled environment
(eg. Ainsworth (1978) ‘the strange situation‘) 
Allows some control of variables.
High reliability of results.
Provides a safe environment to study contentious concepts
More variable control = lower ecological validity.
Higher possible degree of Experimenter (observer) Bias
Unstructured  (Naturalistic) : watching behaviours as they occur in a natural environment.
(eg. Sherman (1975) preschool ‘group glee’)
Gives a broad overview of a situation. Useful where situation/subject matter to be studied is unclear
Only really appropriate as a ‘first step’ to give an overview of a situation / concept / idea

20. Correlational Studies
‘Correlation’ means relationship between variables, so the purpose of a C.S is to determine if one exists, ‘direction’ and ‘strength’ (‘correlation coefficient’), but can NOT assert Causality.
Strength: can make predictions when we know about correlations. If two variables are correlated, we can predict one based on the other.
Weakness: Tells us nothing about possible causes.
[Page 4 of WS;
then p.11]

21. Self Report - Questionnaires
Strengths:
Can test many quickly. Easy to
generate quantitative data and
easy to analyse.
Highly convenient & replicable.
Used to collect large amounts of
data about attitudes/behaviours.
Can quickly show changes in
Attitudes/behaviours before and
after specific events.
Weaknesses:
Social desirability; especially on
sensitive issues (e.g. sexual
behaviour).
Researcher presence may affect
answers. Postal questionnaires
may have low response rate.
Different interpretations of
questions; need standardisation.
[Page 5 of WS]

22. Self Report – Interviews
Structured; Semi-Structured; Unstructured
(compromise between flexibility and consistency)
Strengths:
Detailed information, avoids
oversimplifying complex issues.
Attention to individual’s point of
view (important in clinical psy.)
Interviews may encourage greater
openness in answers.
Weaknesses:
Difficult to analyse if
unstructured and qualitative.
Time-consuming, expensive.
Possible interviewer effects
(rapport with participant; own
Opinions/interests; etc).

23. Case Studies Strengths: Weaknesses:
Following a single case, typically over an extended period of time.
Can involve naturalistic observations, and include psychological
testing, interviews, interviews with others, and the application of a
treatment or observation.
Strengths:
Can gather extensive information,
both qualitative and quantitative
Helpful in better
understanding rare cases or
very specific interventions.
Weaknesses:
Can have severely limited
scope for generalisation.
Can be very time consuming.
Can involve other problems
specific to the techniques used,
including researcher bias.

24. 1) A psychologist carried out a field experiment to investigate the accuracy of eyewitness testimony. The participants were pupils and parents attending a school concert. Just before the concert began, two professional actors had an argument on the stage. During the argument, one actor pushed the other actor. Both actors then left the stage. Some of the audience were approached as they left the concert and were asked to take part in an experiment. Those who agreed were taken to a quiet room and were asked some questions about the argument. For some participants, the questions included, “Did you see the man in glasses push the other man?” In fact, neither man was wearing glasses. The participants were then asked to describe the argument in their own words.
a) What is a field experiment? (2 marks)
b) Other than ethics, outline one weakness of using a field experiment in this investigation. (2 marks)

25. Question 1:
a) A field experiment takes place in the real world rather than in a carefully controlled environment. The IV is manipulated by the experimenter.
1 mark for reference to the environment, real world, naturally occurring, etc. 1 mark for reference to manipulating/changing an independent variable.
b) One weakness of using a field experiment is lack of control of variables. In this case, the participants would be different distances from the staged argument. It would be difficult to replicate the experiment precisely.
1 mark for brief identification of a relevant weakness, 2nd for elaboration.

26. L.O. Be able to evaluate different experiment designs

27. Experimental Design
This is the STRUCTURE of the experiment. There are three experimental designs are commonly used:
Independent groups: Testing separate groups of people, each group is tested in a different condition.
Repeated measures: Testing the same group of people in different conditions, the same people are used repeatedly.
Matched pairs: Testing separate groups of people - each member of one group is matched with a member of the other group.

28. Avoids the problem of participant variables.
Independent groups
Repeated measures
Matched pairs A d v a n t g e s
Avoids Order Effects. If a person is involved in several tests they may become bored by the second test, or become wise to the requirements of the experiment.
Avoids the problem of participant variables.
Fewer people are needed.
Reduces participant variables.
Avoids order effects. D i
More people are needed than with the repeated measures design.
Differences between participants in the groups may affect results (known as Participant Variables).
Order effects are more likely to occur. However,
effect can be minimised by Counterbalancing (ie. alternating the order in which participants perform in different conditions of an experiment. For example, group 1 does ‘A’ then ‘B’, group 2 does ‘B’ then ‘A’ ).
Very time consuming trying to find closely matched pairs.
Impossible to match people exactly.

29. Avoids the problem of participant variables.
Independent groups
Repeated measures
Matched pairs A d v a n t g e s
Avoids Order Effects (If a person is involved in several tests they may become bored by the second test, or become wise to the requirements of the experiment)
Avoids the problem of participant variables.
Fewer people are needed.
Reduces participant variables.
Avoids order effects. D i
More people are needed than with the repeated measures design.
Differences between participants in the groups may affect results (known as Participant Variables).
Order effects are more likely to occur. However,
effect can be minimised by Counterbalancing (ie. alternating the order in which participants perform in different conditions of an experiment. For example, group 1 does ‘A’ then ‘B’, group 2 does ‘B’ then ‘A’ ).
Very time consuming trying to find closely matched pairs.
Impossible to match people exactly.

30. EXERCISE: From the experiment descriptions below work out: Aims; Hypotheses; Design; IVs & DVs; variable Oprationalisation and Experimental Design
1) PPs were tested on their ability to avoid obstacles in a computer driving simulation. Half of them were asked to respond verbally to a series of questions during the simulation. The other half completed the same task but without questions. 2) PPs were given a series of words to learn. All participants took part in 2 conditions; once given words arranged into categories (e.g. items of furniture, means of transport), and another given words randomly arranged. They were tested on recall of the words for each condition.

31. Aims; Hypotheses; Design; IVs & DVs; Oprationalisation; Design
1) Investigating the effect of verbal distraction on driving ability. A verbal distraction task would negatively impact drivers’ ability to avoid obstacles. Independent Group. Verbal task – whether drivers are asked questions or not; Obstacle avoidance – number of obstacles hit. Independent Groups Design. 2) Investigating the effect of categorisation on recall. Word categorisation would improve recall. Repeated Measures. Use of categorisation strategy – whether participants were given categorised or random word lists; recall – number of word recalled correctly. Repeated measure design.

32. A psychologist showed participants 100 different cards, one at a time
A psychologist showed participants 100 different cards, one at a time. Each card had two unrelated words printed on it, eg DOG, HAT. Participants in one group were instructed to form a mental image to link the words. Participants in the other group were instructed simply to memorise the words. After all the word pairs had been presented, each participant was shown a card with the first word of each pair printed on it. Participants were asked to recall the second word.
a) What is the independent variable (IV) in this study? (2 marks)
b) What is the dependent variable (DV) in this study? (2 marks)
c) What experimental design was used in this study? (1 mark)
d) Explain one strength of this experimental design in the context of this study. (2 marks)
e) Explain how a psychologist could find out whether these results are reliable. (2 marks)

33. Reliability and Validity (or “is my experiment worth a damn?!”)
Reliability: refers to the consistency of a test on multiple occasions. A test is considered reliable if repeating it gets similar results. So we can say Reliability = Repeatability.
Validity: does a test measure what it was designed to measure.
For example, do IQ tests really measure ‘intelligence’?
Internal validity: extent to which study is free of design ‘faults’, which may affect results. Was it the IV that affected the DV?
Simply put, is the test measuring what it THINKS it’s measuring?
External validity: inter-related with ‘ecological validity’. This is the extent to which generalisation can be made from the test environment to other situations (i.e. the real world).

34. Is it Reliable and Valid to ...
Measuring a person’s intelligence by measuring the circumference of their skull