Experiments Flashcards
What is a laboratory experiment?
The IV is manipulated by the researcher and the experiment is carried out in a laboratory or other contrived setting away from the participants’ normal environment.
What are the strengths of laboratory experiments?
- High controls produces scientific research which is easy to replicate.
- We can be sure that the variable we manipulate (the IV) is the factor affecting the DV (the results)
What are the weaknesses of laboratory experiments?
- Low ecological validity due to artificial settings.
- The artificial setting or tasks do not reflect real-life events, so behaviour may be artificial.
What is a field experiment?
The IV is manipulated by the researcher but this time the experiment is carried out using participants in their normal surroundings.
What are the strengths of field experiments?
- A more realistic setting for a study, so ecological validity will be higher.
- Behaviour is likely to be more truthful reflections of real-life actions.
What are the weaknesses of field experiments?
- Lack of control of the setting means we can’t always assume the IV is influencing the DV - risk of extraneous variables influencing behaviour.
- There may be ethical issues as participants might not be aware they were in an experiment.
What is a quasi experiment?
The IV is naturally occurring (e.g. cloudy conditions versus sunny conditions), not manipulated by the researcher.
What are the strengths of quasi experiments?
- Can study the effects of variables that researchers can’t manipulate, such as the weather.
- Usually high levels of ecological validity due to the naturally occurring IV.
What are the weaknesses of quasi experiments?
- They can be very difficult (if not impossible) to replicate due to the naturally occurring IV.
- Lack of control over all of the variables, e.g. the social setting, lifestyles- these may be confounding variables that influence the results.
What is the repeated measures design?
Involves using the same people in each condition.
What are the strengths of using a repeated measures design?
- Participant variables will not affect results as it is the same people (with the same range of abilities) who take part in each condition of the experiment.
- Half the number of participants are needed to get the same amount of results as in the other designs.
What are the weaknesses of using a repeated measures design?
- Order effects (either getting worse due to fatigue or getting better due to practice) can affect the results from the second condition.
- To avoid order effects, it may be necessary to create additional test materials (for use in the second condition) which are different yet if an identical difficulty - this may be very hard to achieve.
What is the independent measures design?
Involves using different people in each condition.
What are the strengths of using an independent measures design?
- There is no risk of results being affected by the order in which participants do the task as they only do the task once (unlike in the repeated measured design).
- It is possible to use the same task in each condition, controlling for any differences in this as a possible extraneous variable and making it easier for the researcher.
What are the weaknesses of using an independent measures design?
- Results can be affected by participant variables as there are different people in each condition and, inevitably, there will be individual differences between them.
- Twice as many participants are needed as in repeated measures design just to get the same amount of results.
What is the matched participants design?
Involves using different people in each condition but an attempt is made to make participants as similar as possible on certain key characteristics (any that might influence findings). This is done by testing the individuals on the key characteristics, pairing them based on similar scores, and then placing one member of each pair into each group.
What are the strengths of using an matched participants design?
- You get the benefits of both of the designs: order effects are avoided as participants only take part in one condition of the experiment and participant variables are not a problem as participants are matched on relevant characteristics.
What are the weaknesses of using a matched participants design?
- It is more complicated as participants need to be pre-tested on a relevant characteristic so that they can be distributed evenly across the different conditions of the experiment.
- Twice as many participants are needed as in a repeated measures design just to get the same amount of results.
What are controls?
What are order effects?
If doing the same activity twice, participants may do better the second time due to practice or worse due to fatigue or boredom.
What is counter-balancing?
- Where, when a repeated measured design is used, the participants are split into two groups where one group does the two conditions in one order and the other group does the two conditions on the other order.
- This is a way of controlling situational variables (e.g. order effects).
What are demand characteristics?
Cues in an experiment that communicate to participants what is expected of them and which may unconsciously affect the behaviour of participants.
What are researcher effects?
Describes how results could be affected by a researcher’s behaviour e.g. the researcher may be more encouraging in the experimental condition which could explain the participants’ increased performance rather than the IV being responsible.
What is a single blind?
When the participants do not know the aim of the study.
What is a double blind?
When neither the participants nor those carrying out the research know the aim of it.
What is researcher bias?
When a researcher allows their hopes and expectations for what the data will look like to affect (for example) the data they choose to hold onto or reject from a study or, alternatively, allows it to influence who they choose as participants for their study(e.g. choosing those they think may behave in particular ‘convenient’ ways).
What is a hypothesis?
A precise testable statement of the relationship between two variables.
What is a null hypothesis?
- Predicts that the IV will not have an effect in the DV.
- The null hypothesis predicts that any difference seen will be due to chance factors rather than the IV.
What is an alternative hypothesis?
- Predicts his one variable (the IV) is likely to affect another variable (the DV) .
- Predicts that the IV will affect the DV.
What is a two-tailed alternative hypothesis?
Predicts that the IV will have a significant effect on the DV but it does not predict the direction this effect will go.
What is a one-tailed alternative hypothesis?
Predicts not only that the IV will have a significant effect on the DV but also the direction this effect will go in.
What is operationalisation?
Refers to the process of making variables physically measurable or testable.
What is the target population?
The group of people the researcher is interested in studying.
What is the sample?
The actual group of participants used in the research.