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40 Cards in this Set
- Front
- Back
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What is an experiment? |
An experiment is a way to carry out an investigation in which one variable is manipulated by the experimenter and the effect of this change on another variable is observed or measured. This is done in order to investigate a cause and effect relationship. |
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define the independent variable of an experiment. |
The independent variable (IV) of an experiment is the factor which is manipulated, changed or compared by the researcher. It is expected to have an effect on the dependent variable. |
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define the dependent variable of an experiment. |
The dependent variable (DV) of an experiment is the factor in an experiment that is measured by the researcher. Changes in this factor are predicted to be caused by changes in the IV. |
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What are the levels of the IV? |
The different conditions under which participants are tested in an experiment that are manipulated, changed or compared by the researcher. |
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What is the control condition? |
An experiment characterised by the absence of the IV is known as the control condition. It is used as a baseline for comparison with an experimental condition. |
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In Loftus and Palmer's first experiment, how many levels of IV were there and what were they? |
There were five levels of IV, being the five different verbs used- hit, smashed, collided, contacted, bumped. |
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What is operationalisation? |
The definition of variables so that they can be accurately manipulated, measured or quantified and replicated. |
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Why is operationalisation important? |
Operationalisation is important because in order to be certain about the findings of an experiment we need to know exactly what has changed. For the IV this means knowing precisely how the variable was manipulated and for the DV it means being confident that variation is measured accurately. Therefore must be able to specifically define variables. |
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What is experimental design and what are three common experimental designs? |
Experimental designs denote the different ways in which participants are allocated to the levels of the IV. Three common designs are: - independent measures design - repeated measures design - matched participants design |
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Define independent measures design. |
An experimental design in which different participants are used for each level of the IV. |
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What are the strengths of independent measures? |
- Different participants so there are no order effects. - Participants see the experimental task only once reducing the risk of demand characteristics. - the effects of individual differences can be reduced by random allocation to the levels of IV. |
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What are the weaknesses of independent measures? |
-Individual differences could distort results if participants in one level of the IV differ from those in another. - more participants are needed than with other designs (could be less ethical or harder to find) |
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Define repeated measures design. |
Repeated measures design is an experimental design in which each participant performs every level of IV. |
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What are the strengths of repeated measures design? |
-Individual differences are unlikely to distort the effect of the IV as participants do all levels. - Counterbalancing reduces order effects. - uses fewer participants than independent measures so is good when finding participants is hard. - Blind procedures can reduce demand characteristics. |
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What are the weaknesses of repeated measures design? |
- order effects such as practice and fatigue, and extraneous variables could distort results. - participants see the experimental task more than once increasing the risk of demand characteristics. |
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Define matched participants design. |
Matched participants design is an experimental design in which participants are arranged into pairs. Each pair is similar in ways that are relevant to the study and one member of each pair performs one of the levels of IV. |
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What are the strengths of matched participants? |
- Participants see the experimental task only once, reducing the risk of demand characteristics. - controls for individual differences i.e. identical twins are excellent matched participants. - No order effects |
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What are the weaknesses of matched participants? |
- The similarity between participants is limited by the matching process, which could be flawed if important variables for matching are unknown. - matching participants is time consuming and difficult. |
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Define demand characteristics. |
demand characteristics are features of an experimental setting that indicate to participants the aims of the study and so can influence their behaviour. |
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Define single and double blind experimental procedures. |
a single blind experimental procedure ensures that participants are unaware of the level of IV they perform, reducing the effect of demand characteristics. a double blind experimental procedure protects against both demand characteristics and researcher bias. it ensures that neither the participant or the researcher are aware of the level of IV that is being performed. |
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What are researcher effects? |
the negative influences researchers can have on a study by their presence or beliefs. |
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What are participant variables? |
individual differences between participants that could affect their responses to a study. |
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define order effects. |
in a repeated measures design, order effects can produce changes in performance between conditions that are not the result of the IV, so can obscure effect on the DV |
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What is the practice effect? |
the practice effect refers to the situation in which participants performance improves because they experience the experimental task more than once. |
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What is the fatigue effect? |
the fatigue effect refers to the situation where the participants' performance decreases because they have experienced the task more than once and so may be bored or tired. |
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define counterbalancing. |
counterbalancing is used to overcome order effects; each possible level of IV is performed by a different subgroup of participants. this can be described as the ABBA design. |
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What makes a 'true' experiment different from a 'quasi' experiment? |
in a true experiment a researcher can randomly allocate participants to the levels of IV; in a quasi experiment the researcher makes use of an existing change or difference in situations to create levels of IV and measures a DV in the natural setting of the participants for the activity being tested. |
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What are the differences between a field and a laboratory experiment? |
A field experiment is a study in which the researcher manipulates the IV and measures the DV in the natural setting of the participant for the activity being tested; a lab experiment is a study conducted in an artificial environment in which the researcher manipulates the IV and measures consequent changes in a DV, whilst controlling extraneous variables. |
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define standardised instructions. |
A set of intructions (written, spoken, or recorded) presented to participants to tell them what to do. This ensures that all participants recieve the same treatment and information, so differences between their performance are more likely to be the result of the IV. |
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define extraneous and situational variables. |
Extraneous variables are factors other than the IV that could affect the performance on the DV; situational variables are factors in the environment surrounding participants that can affect their performance on the DV, so obscuring the effect of the IV. |
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What is reliability? |
the consistency of a research method or test. |
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What is validity? |
validity denotes a test's ability to measure what it is supposed to measure. |
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define mundane realism. |
the extent to which an experimental task represents a real world situation. |
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define generalisability. |
the extent to which findings from one situation or sample will apply to other situations or people. |
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What are the strengths of Lab experiments? |
- Good control of extraneous variables. - Causal relationships can be determined. - Strict procedures allow them to be replicated, so researchers can be more confident about their findings. - In a repeated measures design, counterbalancing can be used to reduce order effects. |
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What are the weaknesses of Lab experiments? |
- the artificial situation could make participants' behaviour unrepresentative. - participants could respond to demand characteristics and alter their behaviour. |
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What are the strengths of field experiments? |
- As participants are in their normal situation, their behaviour is likely to be representative. - participants could be unaware that they are in a study so demand characteristics are less problematic than in laboratory experiments. |
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What are the weaknesses of field experiments? |
- Control over extraneous variables is more difficult than in a lab so they are less reliable and replication is more difficult. - The researcher cannot be sure that the changes in the DV have been caused by changes in the IV. - Participants are likely to be unaware that they are in study which raises ethical issues. |
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What are the strengths of Quasi experiments? |
- They can be used to study real world issues. - If participants are in their normal situation, their behaviour is likely to be representative. - If participants are unaware that they are in a study, demand characteristics will be less problematic. - They enable researchers to investigate variables that could not practically or ethically be manipulated. |
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What are the weaknesses of Quasi experiments? |
- They are only possible when naturally occuring differences arise. - control over extraneous variables is often very hard. - as the researcher is not manipulating the IV, they can be less sure of the cause of changes in the DV (a causal relationship cannot be established.) - They are generally hard to replicate. |
