types of experiment Flashcards
research methods
What is a laboratory experiment?
The most scientific method because it involves the highest level of control over all variables. They take place in a controlled environment, with the research taking control in manipulating the IV. All extraneous variables can be controlled so that any changes in the DV can be said to be due to the changes of the IV
What’s an example of a laboratory experiment?
Loftus and Zanni (1975) - All participants were shown a video of a car accident and asked questions about it. On group was asked did you see A broken headlight the other group if they had seen THE broken headlight. The later group were more likely to report a broken headlight showing how leading questions can affect a persons memory
What are the advantages of lab experiments?
They’re easy to replicate and the reliability of the original findings is easy to test
They have a high degree of control as extraneous variables are so well controlled
What are the disadvantages of lab experiments?
Low ecological validity so findings might not be generalisable to real world situations as it’s so artificial
Demand characteristics mean participants may change their behaviour to fit what the experiment does or doesn’t want
What is a field experiment?
Field experiments still involve the manipulation of an IV in order to measure its effect on the DV. The only difference is the location of the experiment, they’re carried out in the participants natural environment so behaviour is measured in the location which it would normally occur
What’s an example of a field experiment?
Piliavin et al (1969) - Helping behaviour was tested in the New York subway. They had confederates collapse and look at whether people would help them. In one condition, when the confederate appeared blind, and the other they appeared drunk. They were quicker to help the blind person than the drunk person
What are the advantages of field experiments?
High ecological validity as it’s done in their own environment so they’re acting as they normally would
Less chance of demand characteristics as they’re often unaware that they’re taking part in the experiment so are unlikely to change their behaviour
What are the disadvantages of field experiments?
Less control so the cause and effect relationship between the IV and the DV isn’t as strong
Potential ethical issues as they may not know they’re taking part in an experiment so they haven’t given consent prior to
What is a natural experiment?
The IV is not directly manipulated by the researcher as it’s something that was going to change anyway. The IV was not planned by the researcher and it’s naturally occurring
What’s an example of a natural experiment
Becker (1995) looked at the effect of TV on the prevalence of eating disorders. He asked a group of Fijian teenage girls a number of questions about their eating habits including whether they vomited to control their weight and about whether they were satisfied with their appearance before TV was introduced in Fiji. He then went back years after TV was introduces and found amongst other things that the number of girls who vomited to control their weight increased from 3% to 15%
What are the advantages of natural experiments?
High ecological validity as the IV is not manipulated at all by the researcher and the environment is not highly controlled
Allows the study of sensitive issues as the IV would be unethical to manipulate
What is a quasi experiment?
Quasi means almost as it’s almost a lab experiment due to the controlled environment but the IV forms part of the participant e.g. age
So participants can’t be randomly allocated to conditions as in a true lab experiment
What is an example of a quasi experiment?
Anastasi and Rhodes (2006) researchers were interested in whether age has an impact on the accuracy of eyewitness testimony (EWT). They divided the participants into the age ranges (young, middle aged and elderly). They then gave then 24 photographs of people to rate for attractiveness. This was a red herring task. The real task was how many of the 24 photographs they could recognise when presented with 48 photographs later on. It was found that the older participants had a slightly poorer recall
What are the advantages of a quasi experiment?
High degree of control they’re often carried out in the same controlled conditions as lab experiments so less extraneous variables
Replicable as they don’t rely on one off or rare situations occurring. When the IV I straight forward, it’s easy to repeat the study with a larger group of participants to check the reliability of the findings
What are the disadvantages of quasi experiments?
Random allocation to conditions is not possible the two conditions could differ on a variable that might affect the DV
It may be difficult to find a sample if one condition of the IV is rare so might be hard to recruit the required
