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Experiment
Used to test a cause and effect relationship between variables under controlled conditions.
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Variables
Any factors that can change in amount or type over time.
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IV & DV
- IV (Independent Variable): the variable that is manipulated or changed in some way in order to assess it effects on the participants' responses.
- DV (Dependent Variable): is expected to change as a result of the IV. Is 'dependent' on the IV.
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Experimental and Control Conditions
- Control condition: provides a standard to be compared against. The IV is not present.
- Experimental condition: is exposed to the IV.
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Operational Hypothesis
- States the causal relationship between the IV and DV to be tested.
- - Must include:
- - the IV
- - the DV
- - the population
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Potential Confounding Variables
- - Individual Participant Differences
- - Demand Characteristics
- - Placebo Effects
- - Experimenter effects
- - Order effects (practice and carry-over)
- - Artificiality
- - Use of non-standardised instructions
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Individual participant differences
e.g. age, sex, memory, intelligence, personality, mood, motivation, social skills etc.
- Ways to control this variable:
- - Matched participant design
- - Double-blind or single-blind procedure
- - Participant allocation and selection.
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Demand Characteristics
A cue expressed by the experimenter or is present in some aspect of the research study which influences the way participants respond. They respond in a way they feel is expected of them rather than responding naturally.
- Ways to control this variable:
- - Placebo
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Placebo effects
Occurs when there is a change in the responses of participants due to their belief that they are receiving some kind of treatment and responding according to that belief.
- Ways to control this variable:
- - Single-blind procedure
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Experimenter effects
Occurs when there is a change in a participant's response due to the researcher's expectations, biases or actions, rather than to the effect of the IV.
- Ways to control this variable:
- - Double-blind procedure
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Order effects
Occurs when performance, as measured by the DV, is influenced by the specific order in which the conditions, treatments or tasks are presented.
- Practice effects are the influence on performance (DV) that arises from practising a task.
- Carry-over effects are the influence that a task has on performance in a subsequent task that follows it.
- Ways to control this variable:
- - Counterbalancing
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Artificiality
Laboratory based research with a lack of realism and differences to real life settings. This can produce demand characteristics which causes a participant to react unnaturally.
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Use of non-standardised instructions
When research procedures are non-standardised, this means that they are not kept uniform or the same for all participants.
- Ways to control this variable:
- - Use of standardised instructions.
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Ways of minimising confounding variables
- - Counterbalancing
- - Single and Double-blind procedures
- - Placebos
- - Standardised instructions and procedures
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Counterbalancing
Involves systematically changing the order of treatments or tasks for participants in a ‘balanced’way to ‘counter’ the biasing influence or unwanted effects on performance of any one order.
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