Chapter 5 – Quasi-experiments and non-experiments
This chapter discusses quasi-experiments, their limitations compared to true experiments, and the challenges to validity in various experimental designs.
Exercises
Exercise 5.1
Some outlines of research studies are given below and your task is to decide which one of the following research designs each study used (some of which are taken from previous exercises). In the absence of specific information assume studies are conducted in a laboratory.
| Research design | Full description |
| Lab experiment (true) | True experiment conducted in a laboratory. |
| Lab quasi | Quasi experiment conducted in a laboratory. |
| Lab non-experiment | Non-experiment conducted in a laboratory. |
| Field experiment (true) | Field experiment (true). |
| Field quasi | Field quasi experiment. |
| Field non-experiment | Field research study, which is not an experiment. |
1. A researcher’s confederate sang identical songs on two separate days, one day dressed scruffily and the other day smartly dressed. Passers-by were asked to rate the busker’s performance on the two separate days.
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Field quasi
2. Participants were allocated at random to one of two conditions of an experiment. In one condition participants were asked to learn a list of 20 words with accompanying pictures. In the other condition, the participants were asked to learn the words without the pictures.
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Lab experiment (true)
3. Children in a nursery were randomly allocated either to a condition where they were shown a film in which several adults behaved quite aggressively or to a condition in which they were shown a nature film. Both groups were then observed for aggressive behaviour.
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Field experiment (true)
4. Male and female dreams were recorded at home by participants for a week and then analysed by a researcher who was testing the hypothesis that male dream content is more aggressive than female dream content.
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Field non-experiment
5. People attending a health clinic and who were fearful of motorway driving were given several sessions of anxiety reduction therapy involving simulated motorway driving. A control group was formed by people on a waiting list who had only recently applied for therapeutic help with the same problem. The therapy participants were significantly less fearful of motorway driving after a three-month period than the control group.
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Field quasi
6. People who had recently experienced a post-traumatic stress disorder were asked by a psychological researcher to undergo a battery of psycho-motor test trials. Compared with non-stressed participants the performed significantly worse.
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Lab non-experiment
7. Psychology students were invited to volunteer for a research study. Because the researcher did not want participants from one condition to discuss the procedure with participants in the other, he asked students from one course to detect stimuli under stressful conditions and students from the other course to do the same task under non-stressful conditions.
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Lab quasi
Exercise 5.2
Select True or False for each item to test your understanding of quasi-experiments and non-experiments.
Weblinks
Quasi-experiments and non-experiments weblinks
We need artificiality in experiments – watch a hammer and feather fall to the ground at the same time (on the moon):