1. Variables and the Experimental Method

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

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

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

5. 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

6. There are 3 types of variables to control
Controls
There are 3 types of variables to control

7. Participant Variables Situational Variables Experimenter Variables
Time of day
Heat
Participant reactivity
Body language
Tone of voice
Age
Intelligence
Personality
Order Effects
Demand Characteristics
Bias

8. Participant Variables

9. Individual Differences
Age, gender, mood, background, ethnicity, IQ, personality, memory, beliefs, past experiences………….

10. Controls for Individual Differences
Allocation
Sample
Randomly allocate to conditions
Sample large and randomly to gain representative samples
Design
Use Repeated Measures or Matched Pairs

11. Controls for Situational Variables
1. Standardise – keep everything the same for each participant
Standardised Procedure
Standardised Instructions

12. Controls for Situational Variables
2. Counterbalance – to reduce effect of situational variables or order effects
Split the group in half
Group 1 do condition 1 > 2
Group 2 do condition 2 > 1
This “balances” out any order effects. E.g. If you do better on the 2nd test, 50% will do better in Condition 1 and 50% do better in condition 2

13. Demand Characteristics
refers to an experimental artefact where participants form an interpretation of the experiment's purpose and unconsciously change their behaviour accordingly

14. Controls for Demand Characteristics Deception Single Blind
Drug
Deception
Distractor questions
Single
Blind
Lying about the aim
The participant is unaware of which condition they’re in
Placebo

15. Experimenter Variables
The experimenter effect is a term used to describe subtle cues or signals from an experimenter that affect the performance of participants in studies.
The cues may be unconscious nonverbal cues, such as muscular tension or gestures. They may be vocal cues, such as tone of voice.

16. Experimenter Variables
My beliefs about what I’m studying can create bias. This could be subconsciously (or consciously). This is experimenter bias.

17. Controls for Experimenter Variables Inter-rater reliability
Double
Blind
Inter-rater reliability
Neither the researcher or the participant knows which condition they are in
Independent raters rate same behaviour as researcher – check for agreement