This post focuses on the practical, theoretical and ethical and strengths and limitations of laboratory experiment, applied mainly to sociology…
What are laboratory Experiments?
Laboratory experiments take place in controlled environments and are the main method used in the natural sciences such as Physics, Chemistry and Biology. There are numerous experiments which have been designed to test numerous scientific theories about the temperatures at which various substances freeze or melt, or how different chemicals react when they are combined under certain conditions.
The logic of the experimental method is that it is a controlled environment which enables the scientist to measure precisely the effects of independent variables on dependent variables, thus establishing cause and effect relationships. This in turn enables them to make predictions about how the dependent variable will act in the future.
For a general introduction to the key features of experiments and the experimental method (including key terms such as hypothesis and dependent and independent variables) and some of their advantages please see this post: experiments in sociology: an introduction.
The laboratory experiment and is commonly used in psychology, where experiments are used to measure the effects of sleep loss and alcohol on concentration and reaction time, as well as some more ethically dubious experiments designed to measure the effects of media violence on children and the responses of people to authority figures.
However, they are less common in sociology. Having said that, they are still a requirement within the research methods component of A-level sociology and the AQA exam board does seem to like setting exam questions on experiments!
Laboratory Experiments: Theoretical Factors
Theoretical Advantages of Laboratory Experiments
Accuracy and Precision– Laboratory experiments allow the precise effects of independent variables on dependent variables to be measured. This in turn makes it possible to establish cause and effect relationships between variables.
Isolation of Variables – The controlled conditions of laboratory experiments allows researchers to isolate variables more effectively than with any other research method. This further allows researchers to precisely measure the exact effect which one or more independent variables have on the dependent variable. With the ‘tomato experiment’ for example, laboratory conditions would allow the researcher to control precisely variations in temperature, moisture and light, this would not be possible in a field (no pun intended).
Controlled conditions also allow the researchers to eliminate the effects of ‘extraneous variables’. Extraneous variables are undesirable variables which are not of interest to the researcher but might interfere with the results of the experiment. If you were trying to measure the effects of alcohol on reaction time for example, keeping respondents in a lab means you could make sure they all at and drank similar things, and did similar things, in between drinking the alcohol (or placebo) and doing the reaction time test.
Laboratory experiments have excellent reliability for two major reasons:
Firstly, the controlled environment means it easy to replicate the exact environmental conditions of the original experiment and this also means it is relatively easy for the researcher to clearly outline the exact stages of the experiment, again making exact replication easier. This is not necessarily the case in a field experiment, where extraneous variables may interfere with the research process in different ways with repeat-experiments.
Secondly, there is a high level of detachment between the researcher and the respondent. In an experiment, the researcher typically takes on the role of ‘expert’ and simply manipulates variables, trying to have as little interaction with the respondents as the experiment will allow for. This means there is little room for the researcher’s own values to influence the way the respondent reacts to an experiment.
Theoretical Limitations of Laboratory Experiments
Laboratory experiments lack external validity – sociologists hardly ever use lab experiments because the artificial environment of the laboratory is so far removed from real-life that most Sociologists agree that the results gained from such experiments tell us very little about how respondents would actually act in real life. Take the Milgram experiment for example – how likely is it that you will ever be asked by scientist to give electric shocks to someone you’ve never met and who you can’t see when they give the wrong answer to a question you’ve just read out? Moreover, when was they last time you were asked to do anything to anyone by a scientist? In the real world context, many of the Milgram respondents may have responded to real-world authority figure’s demands differently.
Laboratory Experiments: Practical Factors
The practical advantages of lab experiments
In terms of practical advantages experiments (assuming they are ethical) are attractive to funding bodies because of their scientific, quantitative nature, and because science carries with it a certain prestige.
Once the experiment is set up, if it takes place in a lab, researchers can conduct research like any other day-job – there is no travelling to visit respondents for example, everyone comes to the researcher.
The practical problems of lab experiments
Practical problems include the fact that you cannot get many sociological subjects into the small scale setting of a laboratory setting. You can’t get a large group of people, or a subculture, or a community into a lab in order to observe how the interact with ‘independent variables’.
Also, the controlled nature of the experiment means you are likely to be researching one person at a time, rather than several people completing a questionnaire at once, so it may take a long time to get a large-sample.
Laboratory Experiments: Ethical Factors
The ethical limitations of laboratory experiments
Deception and lack of informed consent are an ethical problem- The Hawthorne effect gives rise to the firs ethical disadvantages often found in experiments – it is often necessary to deceive subjects as to the true nature of the experiment so that they do not act differently, meaning that they are not in a position to give full, informed consent. This was the case in the Milgram experiment, where the research subjects thought the (invisible) person receiving the shocks was the actual subject rather than themselves.
A second ethical problem concerns harm to respondents. In the case of the original Milgram experiment, ‘many research participants were observed to sweat, stutter, tremble, bit their lips and dig their nails into their flesh, full-blown, uncontrollable seizures were observed for three subjects’.
The ethical strenghts of laboratory experiments
While some laboratory experiments are notorious for their ethical problems, it is at least usually obvious that research is taking place (even if the exact purpose of the research may be hidden from respondents). Also, the benefits to society might well outweigh the costs to respondents.
Milgram’s Experiment on Obedience to Authority, which cites Milgram, S. (1974). Obedience to Authority: An Experimental View. New York: Harper and Row. An excellent presentation of Milgram�s work is also found in Brown, R. (1986). Social Forces in Obedience and Rebellion. Social Psychology: The Second Edition. New York: The Free Press.