Edexcel AS Psychology - Cognitive - Methodology

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  • Created by: Ally
  • Created on: 13-03-12 12:06



Dependant variable – this variable is the one being measured or the result of the experiment. For example, in the investigation into fatigue on driving, the dependant variable would be the measure of the effect of fatigue on driving.

Independent variable – this is the variable that is changed in order to show a difference between environmental conditions. For example, the researcher investigating the influence of fatigue on driving, the independent variable would be the amount of sleep a participant has had.

Operationalisation – this is when we define the circumstances in the experiment in order to make them testable. Or in other words, how you intend to measure the dependant variable and change the independent variable. To operationalise the experiment of fatigue in driving it could see how many cones a participant knocks over in a course or you could test their reaction times.

Hypothesis – Null/Experimental – A null hypothesis is stating that a particular result will only occur by chance; e.g. ‘If by chance, there will be no difference in driving between those who have slept and those who have not.’

An experimental hypothesis predicts the outcome of the experiment; a directional/one-tailed hypothesis chooses that will be a definite difference between the two groups; e.g. ‘Drivers who have slept will be much more efficient drivers than those who have not slept.’ A non-direction/two-tailed hypothesis will claim that there will be some difference between the two groups, it will not take one side and the result could go either way.

Participant design (3 types) – the participant design describes how participants are distributed between experimental conditions. We could make some participants get up early and test their driving and test them again the next day when they’re fully rested. The 3 types are:

Independent measures design – this is when only one of the experimental conditions is test on a group of participants.

Repeated measures design – this is when the same participants are used in all the experimental conditions.

Matched pairs design – this is similar to the independent measures design; however, all participants are matched on a quality or characteristic important to the study.

Order effects – these occur when participants take part in all of the experimental conditions, a repeated measures design is therefore used. The affects are practice and fatigue. The participants may become too practised at the test so their performance might improve or they may become tired so that their performance deteriorates.

Order effects can be controlled by counterbalancing or randomising the experimental conditions. To counterbalance, the participants need to be split between the conditions and to experience them in a different order from the other groups. For example, if there are 2 conditions, A&B, then half the participants will be tested in condition A before condition B and vice versa. These control the order effects because the first and second condition is not the same for every participant – so they are not always wide


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