1. Psychological Investigations Experiments
AS Psychology

2. Question: what makes a piece of research an experiment?
AS Psychology

3. A thing which can vary or change.
Variables
A basic experiment has two variables.
A variable is ...
In psychological experiments we use two types of variables:
Independent Variable – is the variable the experimenter manipulates
Dependent Variable – is the variable the experimenter measures
A thing which can vary or change. 

4. ACTIVITY!
Each person will read out their experiment description
If you have the card with the correct IV, stand up and read it
Then it’s the turn of the person with the correct DV

5. DV: NUMBER OF WORDS RECALLED
IV: TIME OF DAY TESTED
DV: NUMBER OF WORDS RECALLED
IV? DV?
Do students recall more words from a list in the morning or evening?

6. IV: TESTED IMMEDIATELY OR AFTER 30 MINS
DV: NUMBER OF FACES IDENTIFIED
IV? DV?
Can students identify actors’ faces better straight after a film or after a delay of 30 mins?

7. Does listening to music while revising affect A level grades?
IV: MUSIC OR NO MUSIC
DV: A LEVEL GRADES
IV? DV?
Does listening to music while revising affect A level grades?

8. DV: TIME TAKEN TO REACT TO A STIMULUS
IV: 4 OR 8 HOURS SLEEP
DV: TIME TAKEN TO REACT TO A STIMULUS
IV? DV?
Are reaction times slower for drivers who have had 4 hours sleep or 8 hours sleep?

9. DV: NUMBER OF SCORES RECALLED FROM A LIST
IV: FOOTBALL FAN OR NOT
DV: NUMBER OF SCORES RECALLED FROM A LIST
IV? DV?
Will football fans be able to remember a list of football scores better than non-football fans?

10. Do women read facial expressions better than men?
IV: PARTICIPANT GENDER
DV: FACIAL EXPRESSIONS CORRECTLY IDENTIFIED
IV? DV?
Do women read facial expressions better than men?

11. IV: COMPETING WITH OTHERS OR ALONE
DV: NO. OF PRESS-UPS COMPLETED
IV? DV?
Will participants complete more press-ups when in competition with other people than alone?

12. Does caffeine affect ability to understand new mathematical concepts?
IV: TEA/COFFEE/COKE DRUNK OR NO DRINK
DV: GRADE IN A MATHS TEST AFTER A NEW TOPIC
IV? DV?
Does caffeine affect ability to understand new mathematical concepts?

13. statement or prediction
What is a hypothesis??????
A hypothesis is a
statement or prediction
of the results you expect to find after your experiment.
It must include descriptions of the IV and DV

14. Examples from studies you know:
Maguire:
There will be a difference between the hippocampi of taxi-drivers and non-taxi-drivers
Griffiths
There will be no differences in the skill levels of RGs and NRGs
Dement & Kleitman
There will be an association between REM sleep and dreaming

15. What does ‘operationalisation’ mean?
Ensuring that variables are in a form that is easily testable / measurable; it has to be very specific so that the reader knows exactly what you mean and how you are going to measure that variable

16. Try operationalising these DVs:
Educational attainment
Memory
Driving skill
Happiness
Helpfulness

17. Null Hypotheses
As well as writing an ‘experimental’ hypothesis when carrying out research, you will also need to write a null hypothesis. What is a null hypothesis? A null hypothesis is a statement that the IV will make no difference to the DV

18. Your hypotheses might be:
Null hypothesis
There will be no difference in the exam performance of students whether they have a computer in their home or not
Alternative hypothesis:
Students who have a computer at home will achieve higher grades in their AS exams than those who don’t.

19. Your hypotheses might be:
Null hypothesis
Alternative hypothesis:
People eating 5 portions of fruit and vegetables a day will live longer than those who don’t.

20. Your hypotheses might be:
Null hypothesis
There will be no difference in the lifespans of those who eat 5 portions of fruit and veg a day and those who don’t.
Alternative hypothesis:
People eating 5 portions of fruit and vegetables a day will live longer than those who don’t.

21. Your hypotheses might be:
Null hypothesis
Alternative hypothesis:
Men whose wives stay at home while they go out to work will have a happier marriage than those whose wives work

22. Your hypotheses might be:
Null hypothesis
There will be no difference in the happiness of marriages whether the wife stays at home or goes out to work
Alternative hypothesis:
Men whose wives stay at home while they go out to work will have a happier marriage than those whose wives work

23. One-tailed and two-tailed hypotheses NOTE
One-tailed and two-tailed hypotheses NOTE!: (these both refer to the alternative hypothesis, not the null)

24. One-tailed and two-tailed hypotheses
One-tailed hypotheses are predictions that state the direction the results will go in. This is also known as a ‘directional hypothesis’. It states that not only will be there be an effect but you know what effect that will be
Eg: Students will remember words better in a cold room than a warm one

25. One-tailed and two-tailed hypotheses
Two-tailed hypotheses are predictions that do not state the direction the results will go in. This is also known as a non-directional hypothesis. It states that you think there will be an effect but you don’t know exactly what that effect will be
Eg: There will be a difference in the number of words students remember in a hot or cold room

26. Boys score differently on aggressiveness tests from girls
One-tailed or two??
Think – does this state what the effect will be, or just that there will be an effect?
Boys score differently on aggressiveness tests from girls

27. One-tailed or two??
Think – does this state what the effect will be, or just that there will be an effect?
People remember the words that appear early in a list better than the words that appear later

28. One-tailed or two??
Think – does this state what the effect will be, or just that there will be an effect?
People given a list of emotionally charged words recall less than participants given a list of emotionally neutral words

29. Hamsters are better pets than budgies
One-tailed or two??
Think – does this state what the effect will be, or just that there will be an effect?
Hamsters are better pets than budgies

30. One-tailed or two??
Think – does this state what the effect will be, or just that there will be an effect?
Words presented in a written form are recalled differently from those presented in a pictorial form

31. Pick one of the following scenarios and write a null and an alternative hypothesis for it; then state whether you have written a one-tailed or two-tailed alternative hypothesis
Do students recall more words from a list in the morning or evening?
Can students identify actors’ faces better straight after a film or after a delay of 30 mins?
Does listening to music while revising affect A-level grades?
Are reaction times slower for drivers who have had 4 hours sleep or 8 hours sleep?
Will football fans be able to remember a list of football scores better than non-football fans?
Do women read facial expressions better than men?
Do better-qualified people borrow more library books than people with few qualifications?

32. Experimental Design Independent Groups
Different participants take part in each ‘condition’ of the study, e.g. one group studies with TV, one group without
Repeated Measures
The same participants take part in two different conditions, e.g. studying for one test with TV, one without TV
Matched Pairs
Participants are matched (e.g. two students with similar scores on earlier tests) and one takes part in each condition

33. EXPERIMENT 1- real words v. nonsense
You are going to take part in two experiments to demonstrate how each of these designs work in practice.
Repeated measures design
Learn the items on the paper in front of you. You have 1 min to study the items, after this time turn the sheet over and write down as many of the items as you can remember.
You have 1 minute to do this.
Repeated measures design
You will be given one more word list. 1 minute to memorise and then 1 minute to write down as many words as you can remember

34. The same participants did both conditions
That was a repeated measures design experiment because.....?
The same participants did both conditions
(Nonsense and real words)

35. Independent measures design; words v pictures
Each participant only takes part in one condition, e.g. Words or pictures. Half the participants are allocated to one condition and half to the other
Let’s have a go at that now!

36. EXPERIMENT 2 - words v. pictures
Independent measures design
You will ALL be a given a piece of paper for which you must memorise the ten items for 1 minute and then you will be asked to write down as many items as you can remember in 1 minute.

37. Different participants did both conditions
That was an independent measures design experiment because.....?
Different participants did both conditions
(Words and pictures)

38. Strengths? Weaknesses? Experimental design.....
See textbook p15
Experimental design.....
Strengths?
Weaknesses?
Ensure that you can think of strengths and weaknesses for repeated measures and independent measures designs. How might you overcome them? What about matched pairs?

39. Strengths and weaknesses of experiments in general, compared with other research methods
Enable you to test hypotheses by manipulating of an IV; therefore can assume cause and effect
Often low in ecological validity as the situations don’t reflect everyday life
Scientific as follow standardised procedures, enabling replication
Practical problems mean sample sizes are often small, reducing generalisability
Control extraneous variables, improving reliability
May stress participants due to unfamiliar tasks/surroundings
Often produce quantitative data which can be analysed
Often don’t get deep understanding due to lack of qualitative data

40. High levels of control means only the IV can affect the DV
Strengths
Weaknesses
Lab experiments
High levels of control means only the IV can affect the DV
Low in ecological validity meaning doesn’t tell us about real life behaviour
Field experiments
Lower levels of control
Higher in ecological validity
Quasi experiments
Only way of studying some IVs such as gender
Other features of the group may be confounding variable
Independent measures
No order effects
No demand characteristics as they don’t guess the purpose of the study
Repeated measures
Removes individual differences as you are comparing the group against themselves
Order effects
Greater likelihood of demand characteristics
Matched participants
Extraneous variables are well controlled
Other variables may still exist

41. information on the exam
How might you have to
use this
information on the exam
paper?
Let’s have a look......

42. Section B
A researcher wants to conduct an experiment to investigate if there is a difference in the memory ability of primary school pupils in the morning compared to the afternoon. Each pupil will be assessed in both the morning and the afternoon.
a) Describe and evaluate one way in which memory could be measured in this investigation (10)
b) Explain the difference between an independent and repeated measures design (4)
c) Outline one strength and one weakness of using a repeated measures design for this investigation (6)