L1 - Experimental Methods

Question 1

Independent variable (IV)

Answer 1

• variable that researcher manipulates to determine it’s effect in the dependent variable

Question 2

Experimental conditions

Answer 2

When the IV is divided into levels

Question 3

Control condition

Answer 3

• provides a standard against which experimental conditions can be compared
• may be a control condition where IV isn’t manipulated at all

Question 4

Dependant variable (DV)

Answer 4

Variable that’s measured

Question 5

Extraneous variable (EV)

Answer 5

Any variable other then the IV that COULD affect the DV

Question 6

Confounding variable (CV)

Answer 6

Any variable other then the IV that HAS affected the DV

Question 7

Operationalisation

Answer 7

Defining and stating how the variables will be measured
Needed for an experiment to be successful

Question 8

Laboratory experiments

Answer 8

• controlled environment e.g. lab - allows high control over IV and eliminates any EV
• artificial setting
• researcher measures effect of changing IV on DV
• Participants are randomly allocated a condition
• other variables research wants to hold constant are EV - researcher controls them to minimise impact on investigation

Question 9

Lab experiments advantages

Answer 9

1) high level of control over IV and the conditions, so easy to control for any extraneous variables and prevent them from becoming CV which may affect measurements/data collected

2) researcher can manipulate IV and can establish a cause and effect relationship between the IV & DV

3) a lab experiment can be easily replicated by other researchers to see if similar results can be obtained. If the findings are similar to the original study then the results are reliable

Question 10

Lab experiment disadvantages

Answer 10

1) with lab experiments demand characteristics may occur within the study - may guess the aim of the study and then change behaviour accordingly - makes data invalid. Some participants behave in a more positive light than normal - can be called social desirability bias

2) with lab experiments establishing a high level of control over the IV & EV means that the experimental situation can often lack mundane realism (extent to which it reflects real life). This means that it lacks ecological validity (ability to generalise the findings of a piece of research to real life situations or other places)

Question 11

Field experiments

Answer 11

• carried out in the real world or in a natural setting instead of the artificial setting of a lab experiment
• IV is still manipulated/controlled by research to see effect on DV

Question 12

Field experiment advantages

Answer 12

1) there is more mundane realism and ecological validity than in a lab and it reflects real life more then a lab experiment

2) in a field study the researcher can manipulate the IV - a cause and effect relationship can be established between the IV & DV

3) There is less chance of demand characteristics compared to a lab experiment, in a field experiment the participants may not even be aware that they are taking part in research do they will behave more naturally and more valid data will be collected

Question 13

Field experiment disadvantages

Answer 13

1) less control over EV compared to lab experiments so the effect on the DV may not be caused by the IV but by EV - this means research may not be valid

2) there is less control over the sample (people taking part in the experiment) - so the sample may not be very representative of the target population

3) may be difficult to replicate which means that they might be unreliable especially when compared to laboratory experiments

Question 14

Natural experiments

Answer 14

• researcher takes advantage of naturally occurs IV to see its effect in the DV
• measures variable that aren’t directly manipulated by the experimenter e.g. comparing behaviour in single sex and mixed school - means IV is naturally occurring
• effectively, experiments finds participants who already meet experiment conditions instead of allocating them to conditions themselves

Question 15

Natural experiment advantages

Answer 15

1) an advantage is that there is a high level of mundane realism and ecological validity compared to laboratory experiments

2) they are useful when it’s impossible or unethical to manipulate the IV/sample in a lab/field experiment

Question 16

Natural experiment disadvantages

Answer 16

1) low control over extraneous variables compared to a lab experiment
2) very difficult to replicate, this means that they are often unreliable and if they experiment was repeated it’s very unlikely that the same results would be gained again
3) difficult to determine cause and effect due to low levels of control

Question 17

Quasi experiments

Answer 17

• contains a naturally occurring IV - it’s a difference between people that already exists
• researcher examines effect of this variable on the DV
• usually happen in a lab setting
• quasi experiments involve a little bit of manipulation
  E.g. males have high levels of testosterone than females in sample of 50 men & 50 women aged 40-70, psychologists may want to study this natural difference between the 2 genders and see what effect it may have on the DV (aggression levels)

Question 18

Quasi experiment advantages

Answer 18

1) high level of control, EV effects are minimised so experimenter can be more confident that the IV has affected the DV

2) replication is very likely, due to strict controls this means that it’s easier to replicate the study to test the reliability of findings

Question 19

Disadvantages of quasi experiments

Answer 19

1) lacks ecological validity because the setting is artificial - may not be a reflection of real-life behaviour

2) Demand characteristics - participants may accurately or inaccurately guess the aim of the experiment and respond accordingly to what they think is being investigated, this can affect the data collected and the results of the study (invalid)