Experimental Methods: Extraneous Variables & Controls

Question 1

● What is an extraneous variable?

Answer 1

An unwanted variable other than the IV that could affect the DV

Question 2

● What does EV stand for?

Answer 2

Extraneous Variable

Question 3

● What is a confounding variable?

Answer 3

An EV that has affected the DV

Question 4

● What are the three types of extraneous variables?

Answer 4

Situational, participant, experimenter

Question 5

● What is a situational variable?

Answer 5

An EV related to the environment

Question 6

● What is a participant variable?

Answer 6

An EV related to the participant’s characteristics

Question 7

● What is an experimenter variable?

Answer 7

An EV related to the researcher

Question 8

● What is meant by internal validity?

Answer 8

The extent to which the IV affects the DV

Question 9

● What is a demand characteristic?

Answer 9

Clues that cause participants to change their behaviour

Question 10

● How do demand characteristics affect a study?

Answer 10

They reduce internal validity

Question 11

● What is meant by controls in an experiment?

Answer 11

Steps taken to reduce EVs

Question 12

● What is standardisation?

Answer 12

Using the same instructions and procedures for all participants

Question 13

● What is randomisation?

Answer 13

Making parts of the procedure random to reduce bias

Question 14

● What is random allocation?

Answer 14

Randomly placing participants into conditions

Question 15

● What is counterbalancing?

Answer 15

Controlling order effects by varying the order of conditions

Question 16

● What is a single blind procedure?

Answer 16

Participants do not know the study’s aim

Question 17

● What is a double blind procedure?

Answer 17

Neither participant nor experimenter knows the aim

Question 18

● What is experimenter bias?

Answer 18

When the researcher’s actions influence the results

Question 19

● What is the aim of controls?

Answer 19

To increase internal validity

Question 20

● What is the role of a standardised script?

Answer 20

To ensure consistency across all participants

Question 21

▲ Why must a researcher control extraneous variables?

Answer 21

To ensure the IV is the cause of the DV changes

Question 22

▲ Which type of EV is influenced by IQ or personality?

Answer 22

Participant variable

Question 23

▲ Why is demand characteristics a problem in lab experiments?

Answer 23

Participants are more likely to guess the aim

Question 24

▲ How can we reduce the impact of experimenter variables?

Answer 24

Use a researcher unaware of the aim

Question 25

▲ Why does random allocation reduce bias?

Answer 25

Each participant has an equal chance of being in any condition

Question 26

▲ Why is a standardised script used?

Answer 26

To reduce differences in how instructions are delivered

Question 27

▲ How does counterbalancing improve internal validity?

Answer 27

It spreads order effects across conditions

Question 28

▲ What is an example of a situational variable?

Answer 28

Noise, lighting, time of day

Question 29

▲ What is an example of a participant variable?

Answer 29

Age, IQ, gender

Question 30

▲ Why is using the same environment for all participants important?

Answer 30

To reduce situational EVs

Question 31

▲ How can we prevent demand characteristics?

Answer 31

Use a single blind or deception

Question 32

▲ How does experimenter awareness of the aim create bias?

Answer 32

They may give cues or behave differently

Question 33

▲ What would happen without controls in an experiment?

Answer 33

Results may be affected by EVs

Question 34

▲ What is the purpose of randomisation when presenting a word list?

Answer 34

To prevent researcher bias in word order

Question 35

▲ Why does counterbalancing use an ABBA structure?

Answer 35

To distribute order effects across both conditions

Question 36

✪ Why do extraneous variables lower internal validity if not controlled?

Answer 36

They can affect the DV and confuse the effect of the IV

Question 37

✪ How does experimenter bias reduce internal validity?

Answer 37

Their actions may unintentionally influence participant behaviour

Question 38

✪ Why are demand characteristics more likely in repeated measures designs?

Answer 38

Participants take part in all conditions and may guess the aim

Question 39

✪ How do standardised instructions increase internal validity?

Answer 39

They reduce variability in how participants are treated

Question 40

✪ Why is a double blind procedure better than single blind for validity?

Answer 40

It controls both participant and experimenter bias

Question 41

✪ How can situational variables become confounding variables?

Answer 41

If not controlled, they directly affect the DV

Question 42

✪ Why is it incorrect to say that controls eliminate order effects?

Answer 42

They only reduce or balance them, not eliminate

Question 43

✪ How does the use of another researcher reduce demand characteristics?

Answer 43

They do not know the aim and give fewer cues

Question 44

✪ What is the consequence of uncontrolled participant variables in independent designs?

Answer 44

They may create differences in DV not due to IV

Question 45

✪ Why must researchers not decide the order of conditions?

Answer 45

To prevent bias—randomisation is needed