Cognitive Research methods Flashcards
Types of experiments
what is a laboratory experiment and the advanages and disadvantages? (give examples)
- The IV is directly manipulated, all other extraneous variables are controlled and participants are randomly allocated to conditions
- e.g. Milgram, Baddeley
Advantages:
- high controlled confident in control of extraneous variables. So we know that only the IV has affected the DV. Claim a cause and effect relationship
Disadvantages:
- more artificial environment: behaviours observed may be less natural, they are less representative of everyday behaviours
Types of experiments
what is a field experiment and the advanages and disadvantages? (give examples)
- The researcher controls the IV but the experimenter cannot control other extraneous variables to the same extent that one can in the laboratory
- participants are not necessarily randomly allocated to conditions
- e.g. sebastian and gill
advantages:
- more natural environment: behaviours more representative of everyday instance of the behaviour, therefore the findings of the study can be applied
disadvantages:
- difficult to control: hard to control all the confounding variables. Therefore, factors other than the IV may have affected the DV. More difficult to conclude changes in DV are due to IV manipulation
Potential issues of experimental designs
what are the potential issues for experimental designs?
- order effects - occurs when participants’ reponses in the various conditions are affected by the order of conditions to which they were exposed
- demand characteristics - cues in an experiment that can lead participants to change their behaviour or responses based on what they think they research is about
- participant variables - (individual differences between participants) affecting the results between conditions, rather than solely manipulation of the independent variable
- number of participants required in a sample - matching participants is a more complex process it is difficult to find a large number of participants that match each other identically
potential issue management of experimental designs
how do you control the issues faced by each design?
Independent group design:
- crucial that participants are randomly allocated to the different conditions
- differences should be quite small using randomisation
Repeated measures design:
- order effects can be controlled through counterbalancing
- means that the participants go through the conditions in different orders
- there should be an equal number of participants going through each order
- this mean that the order effects are removed, of each group and condition cancels each other out
Matched paird design:
- monozygotic twins (identical) provide researchers with a very close match for participants variables, so are favoured
- not possible, so researchers must start with a large group of participants to increase chances of getting suitsbly matched pairs
evaluation of experimental designs
evaluate a strength of repeated measures design
it is possible to remove participant effects. For example, if a person has 5 years driving experience in condition A (no alcohol) then they also have 5 years’ experience in condition B (alcohol), the participant variable is the same for both conditions. Therefore, any difference in their driving is due to the alcohol and not their experience
evaluation of experimental designs
evaluate a weakness of repeated measures design
Order effects may occur when participants take part in more than one experimental condition. Order effects can confound the results in two ways - either negatively through the effects of fatigue or boredom, or positively through the effects of learning or practice.
evaluation of experimental designs
evaluate a strength of matched pairs design
there are no order effects and there is a good attempt at controlling participant variables.
evaluation of experimental designs
evaluate a weakness of matched pairs design
matching pairs of participants can be difficult and time consuming: It depends on the use of reliable and valid procedures for pre-testing participants to identify the matched pairs. Complete matching of participants on all variables that might affect performance can rarely be achieved.
evaluation of experimental designs
evaluate a strength of independent groups design
avoids order effects altogether and also participants less likely to guess aims of study and show demand characteristics as they only take part in one condition.
evaluation of experimental designs
evaluate a weakness of independent groups design
has no control for participant variables, which could influence experiment’s results
How do you choose the correct test?
Independent group experiment
- Nominal = Chi-squared (x^2)
- Ordinal (at least) = Mann Whitney (U)
Repeated measures/ matched pairs
- Nominal = N/A
- Ordinal (at least) = Wilcoxon (T)
Relationship (correlation)
- Nominal = N/A
- Ordinal (at least) = Spearman’s Rank (rho)
