Psychological Investigations Experiments

Psychological Investigations Experiments AS Psychology

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

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.

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

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?

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?

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

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?

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?

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

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?

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?

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

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

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

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

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

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.

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.

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.

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

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

One-tailed and two-tailed hypothesesNOTE!: (these both refer to the alternative hypothesis, not the null)

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

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

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

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

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

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

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

Experimental Design

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

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

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!

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.

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

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?

Strengths and weaknesses of experiments in general, compared with other research methods

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

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)

Psychological Investigations Experiments