Experiments Flashcards
Name all types of experimental methods
Lab, Field, Natural, Quasi
Explain Lab experiment (strengths and weaknesses)
Experiment is conducted under controlled conditions, researcher deliberately changes something in IV to affect DV so it has higher internal validity.
Strengths = control & replicable.
weaknesses = lacks ecological validity
Explain Field experiment (strengths and weaknesses)
These experiments are carried out in a natural setting, in which the researcher manipulates something (I.V.) to see the effect of this on something else (D.V.).
Strengths = good validity
weaknesses = less control so more extraneous variables
Explain Natural experiments (strengths and weaknesses)
Conducted in the everyday (i.e. real life) environment of the participants, but here the experimenter has no control over the independent variable as it occurs naturally in real life.
Strengths = high ecological validity ( behavior in a natural experiment is more likely to reflect real life because of its natural setting ) and no demand characteristics.
Weaknesses = Expensive and no control so extraneous variables may occur.
Explain demand characteristics .
When a participant gains characteristics because they guess what the experiment entails, they then try to alter their traits and match these of what the experiment needs.
What is IV and DV ?
IV = factor that is directly manipulated by researcher in order to test its effect on DV
DV = factor measured by researcher
Hypothesis must be operationalise the variables, what does this mean ?
State how IV is manipulated and how the DV will be measured.
What are the three types of hypothesis ?
Null, One tailed alternative (directional), Two tailed alternative (non - directional)
Explain Null hypothesis
Predicts no difference between conditions or no correlation between groups. States results are due because of chance alone.
Explain One tailed (directional) hypothesis
Predicts there will be a difference between two conditions or correlation and states the direction of the difference. EG group A will have higher score than group B
Explain two tailed (non - directional) hypothesis
Predicts there will be a difference between two conditions or correlation but doesn’t state direction of the difference. EG The score between groups A and B will be different.
Explain difference between Non-directional and Directional hypothesis
Non - directional = no past research or past research is contradictory.
Directional = Past research suggests findings will go in particular direction.
What does a good hypothesis contain ?
Dv and how it’ll be measured, Iv and how it’ll be manipulated …. (operationalising variables) and what the psychologist expects to find.
What are the two types of variables that can interfere with results ?
Extraneous variable, Confounding variable
What is extraneous variable, What is confounding variable ?
Extraneous = variables that may affect DV [ reduce validity ]
Confounding = variables that HAVE affected DV [ reduce validity ]
Name the 3 types of experimental designs.
independent groups, Repeated measures and matched pairs.
Explain Independent groups and give limitations / how to deal with them.
Participants placed in separate groups EG Group A does test with Tv on and group B does test with Tv off then compare DV.
Limitations:
- researcher can’t control participant variable (height etc) people in one group might have better memory.
- needs a lot of participants
Dealing with this:
- randomly allocate participants to conditions trying best to distribute variables.
Explain repeated measures and give limitations / how to deal with them.
[2 groups] All participants do test once then do it again later experiencing all of IV equally. EG Group 1 and 2 does test A then 3 weeks later does test B, then compare the results between the tests.
Limitations:
- Order effect (boredom / anxiety / stress) could occur second time round.
- When participants do the second test they know the aim.
Dealing with this:
- Counterbalancing (Reshuffle tests); EG Group 1 does test A then test B however group 2 does test B then test A (ABBA)
- Cover main idea of the tests
Explain matched pairs and give limitations / how to deal with them.
Use 2 groups and match key characteristics believed to affect performance on Dv.
- One member of each pair allocated to each group and then rest of experiment takes place like “independent groups”
Limitations:
- Very time consuming to find people who have matching characteristics
- Can only match suitable variables EG Could do a memory test but one person could have had memory booster classes
Dealing with this:
- restrict number of variables needed to match
- pilot study to consider key variables ( test run )
