Experiments: Extraneous Variables

Question 1

What are extraneous variables

Answer 1

Variables (not the IV or DV) that have not been controlled and that may have an impact on the dependent variable

Question 2

What is a confounding variable

Answer 2

• a type of extraneous variable
• they’re variables that have varied systemically with the IV and therefore may be a reason for the change in the DV rather than the IV itself
• they happen in one condition and not the other = don’t know true impact of IV on DV

Question 3

What are the 5 types of extraneous variables

Answer 3

• participant variables
• situational variables
• order effects
• Demand characteristics
• Researcher bias (Direct and Indirect)

Question 4

What are participant variables

Answer 4

• characteristics of individual participants that might influence the outcome of a study
• e.g. gender, IQ, height, age

Question 5

What are situational variables

Answer 5

• Any factor in the environment that could affect the DV
• e.g. temp, time, lighting, distractions

Question 6

What are order effects + which design to they occur in

Answer 6

• Arises from order in which conditions (IV1 and IV2) are presented
• e.g. practice, boredom, fatigue
• they only happen in repeated measures design

Question 7

What are Demand characteristics

Answer 7

• A cue that makes participants aware of the aims of the study or helps participants work out what the researcher expects to find
• this causes the participant to therefore change their behaviour

Question 8

What is researcher bias

Answer 8

• Anything an investigator does that has an effect on the participant’s performance in a study
• this can be direct + indirect

Question 9

What is direct researcher bias

Answer 9

• interacting with participants
• e.g. gestures/tone

Question 10

What is indirect researcher bias

Answer 10

• how the study is designed
• e.g operationalising/duration

Question 11

How can we control participant variables

Answer 11

• Through our samples (must be large + random)
• through our experimental design (repeated + matched pairs help)
• Through our allocation to conditions (randomly allocate participants to condition)

Question 12

How can we control situational variables

Answer 12

Standardise
1. Standardised procedure (they do it when task is given)
2. Standardised instructions (written, recorded, printed…)

Question 13

How do we control order effects

Answer 13

• use independent/matched pair design
• counter balancing (split sample in half. Half do conditions A then B, other half does B then A)

Question 14

How do we control demand characteristics

Answer 14

Deception
- lie about aim
- filler Qs
- Distraction task

Experimental realism
- make task engaging so that participant pays attention to the task, rather than the fact they’re being observed

Single blind
- participant is unaware of what condition they’re in

Question 15

How can we reduce researcher bias

Answer 15

Double blind
- Neither researcher or participant know which condition they’re in

Inter-rater reliability
- an independent researcher rates same behaviour at the same time as researcher,
- then they check for agreement (high positive correlation)

Question 16

What is validity

Answer 16

Whether an observed effect is genuine

Question 17

What is internal validity

Answer 17

The degree to which a study or test is measuring what it indented to measure

Question 18

Why do we control for extraneous variables

Answer 18

1. To establish cause and effect
2. To gain findings that are more valid (internal validity)
3. Research is more scientific if it has high validity

Question 19

What is external validity

Answer 19

The degree to which a research finding can be generalised to other situations and people

Question 20

What is ecological validity

Answer 20

• the extent to which we can generalise findings of research beyond the particular setting in which it was carried out
• i.e. if setting was unnatural = can’t generalise: because its not reflective of normal behaviour

Question 21

What is historical validity

Answer 21

• the extent to which we can generalise findings of the research over time
• i.e. do findings 50 years ago still apply today?

Question 22

What is population validity

Answer 22

• the extend to which we can generalise the findings of the research to other groups of people beyond those who were used in the sample
• i.e. is the sample used representative of others

Question 23

What is mundane realism

Answer 23

• Whether tasks used in research are reflective of everyday tasks + experiences or artificial + unnatural
• i.e. memorising and recalling lists of 2 letter groups isn’t everyday example of memory