Experiments

Definition: Conducted in an artificial environment in an attempt to control all of the variables

Advantages

• High levels of control limit effects of confounding variables
• Replication is possible to test for reliability
• Causal relationships can be made

Disadvantages

• Results lack ecological validity because of the artificial environment
• Participants may show demand characteristics because they know they're being studied
• If deception is needed to allow a realisitc reaction ethical issues may be involved as the Pps did not give informed consent

Definition: Behaviour studied in natural environment but the IV is still manipulated

Advantages

• High ecological validity as is conducted in a natural environment
• Pps are usually unaware they're being studied so do not show demand characteristics

Disadvantages

• Lack of control means that confounding varaibles are more likely to have an effect and a causal relationship is harder to establish
• Ethical issues can be a problem because Pps have not usually given informed consent and don't know they're being studied

Definition: IV is not directly manipulated as is naturally occuring eg. gender, criminal record, age

Advantages

• Makes relationships ethically possible to investigate as the IV is naturally occuring

Disadvantages

• There is no control over extraneous variables so a causal relationship is hard to establish

Definition: Different Pps are allocated randomly to each condition of the experiment

Advantages

• No order effects - practise or fatigue
• Pps less likely to figure out what the experiment is about so less likely to have demand charactertistics

Disadvantages

• More Pps are needed to find to participate which is time consuming
• Participant variables may effect results - Pps in one condition may have a trait which advantages them above others

Definition: The same Pps are used in all conditions

Advantages

• Fewer Pps are needed so it saves time
• Participant variables are prevented as same in each condition

Disadvantages

• Order effects may influence results either by practise or fatigue
• Pps may work out what the experiment is about and show demand characteristics

Definition: Pairs of participants are closely matched on characteristics and then randomly allocated to one of the conditions

Advatages

• Reduces participant variables effecting results as characteristics matched
• Avoids order effects as different Pps used

Disadvantages

• Matching and finding pairs is very time consuming and can be difficult
• It is impossible to match each pair completely so participant variables may still have an effect

Aim - The purpose of the study

Hypotheses:

• Directional = a prediction of a specific outcome. Saying the independent will affect the dependent in a specific way
• Non-directional = a general prediction of the outcome. Saying the independent will affect the dependent but not how
• Null = a predicition that the independent will have no affect on the dependent

Variables

Something which can vary within a study

• Extraneous/confounding = Uncontrolled variable which may have affected the dependent