There are many different research designs that a researcher can choose from when planning their experiment. One of the most commonly used research design is the laboratory experiment. This week I am going to be exploring this type of experiment and underlining why I believe the weaknesses of laboratory experiments outweigh the strengths.
A laboratory experiment is conducted under highly controlled conditions. Participants are brought to a lab setting to be tested. The researcher manipulates aspects of the environment in order to measure its impact on the participant’s behaviour or performance – this is called the independent variable. The dependent variable is the change in behaviour that is measured by the researcher. The dependent variable is believed to be under the control of the independent variable. All other variables are controlled as far as possible. This way, conclusions of cause and effect can be made since only the independent variable is controlled so it is assumed that this is what causes the behaviour change.
One clear example of a laboratory study was conducted by Liebert and Baron (1972)*, who were investigating aggression in children. The participants in this study consisted of 5 – 9 year old children. The children were split into two groups; the first group watched a violent video clip that contained fighting, shooting and stabbing, whereas the second group watched a nonviolent, exciting video clip. Making the independent variable the type of program watched. The children were then taken to another room, in which there was two buttons. The children were told that another child in the next room was completing a handle-turning game, and that if they pressed the ‘HELP’ button, the handle would become easier to turn for the other child, but if they pressed the ‘HURT’ button the handle would become very hot and hurt the child. The amount of times each button was pressed was measured by the researcher as aggression – this was the dependent variable in the study. It was found that both boys and girls were more likely to press the ‘HURT’ button if they had watched the violent video.
Although laboratory experiments are thought to have high levels of control, it is very difficult to control every single different variable that may be having an effect on the results. Confounding variables are factors (other than the independent variable) that could cause changes in participants’ performance on the dependent variable if not properly controlled by the experimenter. For example, in the study conducted by Liebert and Baron, the children who watched the violent video clip and pressed the ‘HURT’ button more frequently may have been naturally more aggressive than the other participants. So, the children’s pre-existing levels of aggression may have been acting as a confounding variable, and the independent variable may have had no effect. Although people can argue that laboratory experiments can display cause and effect due to their high levels of control, it is next to impossible to completely control every variable. There may be other variables having an impact that the researcher is unaware of, which is why I believe that the results from laboratory experiments cannot always be fully trusted.
This high level of control leads to experiment settings that are very unnatural, and participants are often asked to complete very strange and bizarre tasks. Therefore, individuals are more than likely going to behave very differently in laboratory experiment situations than they would in real and natural settings. Consequently, laboratory experiments lack ecological validity and mundane realism, as they are not true to real life. For example, in the study conducted by Loftus and Palmer (1974)** into the eyewitness testimony, participants watched a video clip of a car crash and then asked to estimate the speed of the travelling car. This study was obviously conducted in an artificial setting. Watching a video of a car crash would not create the same emotional impact as seeing a car crash in real life. This lack of ecological validity that surrounds laboratory experiments also makes it very difficult to generalise finding from experiments to real life situations.
Although it is believed that laboratory studies should have high internal validity, this can be greatly reduced by demand characteristics. Demand characteristics are cues that may allow participants to guess the aim of the experiment. If a participant is aware of certain aspects of the experiments they may try to behave in a way that they think they are expected to behave. For example, whilst on their way to participate in Bandura’s bobo doll study, a four-year-old whispered to her mother: ‘Look mummy, there’s the doll we have to hit’ (Noble, 1975)*** (hitting the doll was one of the dependent variables being measured in this study). This is a clear example of a participant displaying demand characteristics. So, again, the realism of laboratory studies is reduced by demand characteristics.
One further problem of laboratory experiments concerns ethics. There must always be some form of deception involved in such experiments. If the participants knew every aspect of the study, then it would be pointless to carry it out. In order to produce valid results, participants must be deceived to some extent. However, there are guidelines that must be followed regarding ethics, making it difficult for researchers to produce ethical research.
All of these points lead me to believe that laboratory experiments are more trouble than they are worth. The only positive aspect is that they are highly controlled, therefore cause and effect can be established. However, it is next to impossible to control ever variable within an experiment, therefore confounding variable may be causing the behaviour change instead of the independent variable. Furthermore, this high control can lead to experiments lacking ecological validity, which leads to problems with generalising the results. Demand characteristics may cause participants to behave in an unusual way in order to please the experimenter, again causing a reduction in the validity of the results. Finally, ethical issues of deception may get in the way of researchers creating efficient experiments. Overall, I believe laboratory experiments to be very unnatural and they produce distorted views of how individuals behave in certain situations. Due to the many weaknesses surrounding laboratory experiments, I conclude that results from such experiments cannot be trusted.
* Liebert, R. M., & Baron, R. A. (1972). Some immediate effects of televised violence on children’s behaviour. Developmental Psychology, 6, 469 – 475.
*** Noble, G. (1975). Children in front of the small screen. London: Constable.