Laboratory experiments play a major role in psychological research. They allow us to find a cause and effect relationship between variables that would not be possible with many other research methods.
Laboratory experiments use different conditions to measure the effects of increasing the manipulation of the independent variable. The variable that is measured is called the dependent variable. Often, laboratory experiments consist of two conditions; the experimental condition and the control condition. In the experimental condition, the independent variable is manipulated, whereas in the control condition, it is not. This allows us to see how the independent variable affects the dependent variable and we can therefore see a direct cause and effect relationship.
Laboratory experiments also allow for tight controls which prevent any extraneous variables from affecting the results, as these could possibly affect the results. If extraneous variables were not controlled for, the reliability of the results gained would be reduced as the same or similar results would not be collected if the research was repeated. In general, because of the controls put in place, the level of reliability is relatively high for laboratory experiments.
Laboratory experiments also produce quantitative data. This means that analysis of the results is more objective as fewer subjective interpretations can be made. However, this data does not provide an explanation as to why the results occurred but do allow us to see a relationship and find any anomalies.
Laboratory experiments do lack ecological validity. If ecological validity is present, a method is representative of a real-life situation. Laboratory experiments lack this because the environment is artificial. This means that participants may not behave in the same way as they would in a real-life situation and so the results become less valid. An example of this would be Loftus and Palmer (1974). In the study, participants were asked to watch clips of traffic accidents then answer questions from a questionnaire. They were asked to estimate the speed of the cars in the collision by a critical question that had a verb changed to make leading questions. It could be said that ecological validity is lacking from this piece of research because participants watched clips of collisions and so their levels of adrenalin would not have been massively increased and so they wouldn’t have experienced the same biological and emotional reaction as they would in real-life. This is machine reductionism.
In conclusion, I believe that laboratory experiments are possibly the most important pieces of research in psychology due to the chance to see a direct cause and effect relationship and also reduce the effects of extraneous variables. They allow for high reliability and collect objective data. However, the lack of ecological validity does reduce the usefulness but I think it is more important to have reliability and show relationships between variables rather than be representative of a real-life situation.
Loftus, E. F. & Palmer, J. C. (1974) Reconstruction of automobile destruction: An example of the interaction between language and memory. Journal of Verbal Learning and Verbal Behaviour, 5, 585-589.