Experimental method

What is an independent variable?

Variables that the researcher can manipulate

What is the dependent variable?

Variables measured by the researcher

How do the independent and dependent variables relate to each other?

Any affect on the DV should be as a result of the IV

Variables must be _______________

Operationalised

What is operationalisation?

Clearly expressing a variable in a way it can be measured

What would an operationalised DV look like?

Including measurement scale (eg time in seconds)

What would an operationalised IV look like?

Clearly expressing each level

What is an extraneous variable?

Any variable (that is not the IV) that could influence the measurement of the dependent variable.

How can extraneous variables cause errors in results?

Interferes with the IV

What is a participant variable?

Characteristics such as age, gender, cultural background and prior knowledge can influence behaviour

What is a situational variable?

Environmental factors such as noise, temperature etc

What are order effects?

In a repeated measure, a participant completing one trial can alter their behaviour in the second performance.

Why may someone’s second performance improve?

Practice

Why may someone’s second performance worsen?

Fatigue

What is a confounding variable?

Variable other than the IV that changes systematically between the levels of IV → as you change the IV, you change the CV

How does the CV affect the DV?

CV changes the true effect on the DV as the researcher ends up measuring the CV’s influence on the IV

How does an EV turn into a CV?

If not controlled

What are demand characteristics?

If the participant thinks they have discovered the aim, they may alter their behaviour to match what they think the researcher wants

Why may demand characteristics occur?

Body language/tone of voice from the researcher or a set up that makes the aim obvious

How may demand characteristics change the participant’s behaviour?

Participant may underperform to sabotage the experiment, or over perform to please the researcher → affects the DV as the behaviour is unnatural

What are investigator effects?

Any effect of the researcher’s conscious/unconscious behaviour on the DV

What is randomisation?

Use of chance methods to remove bias

What is standardisation?

Using the same formalised procedures/instructions for every participant

What is an aim?

Idea developed from theories

What is a hypothesis?

A statement that is made at the start of the study and clearly describes the relationship between variables as stated by the theory

What is a directional hypothesis?

A clear difference is established between two conditions

What is a non-directional hypothesis?

Simply states a difference between conditions, but the nature of the difference is not specified

When would a researcher use a directional hypothesis?

When a theory or findings from a previous study suggest a particular outcome

When would a researcher use a non-directional hypothesis?

1. When there is no previous theory or research

2. When findings from earlier studies are contradictory