Experiments — The Cornerstone of Psychology
The basic idea of psychological experimentation is that researchers manipulate certain aspects of a situation to see what happens to the behavior of participants or subjects as a result. What the researcher manipulates is called experimental conditions. If the experiment is conducted according to proper procedures, and if the participants’ or subjects’ behavior differs as a result of the experimental conditions, the researcher can conclude that the manipulation caused the difference.
An Example Experiment
Here's a classic experiment on children and how they learn aggressive behavior, conducted in the 1960s by Albert Bandura (1925– ), a prominent social-learning theorist. Three groups of young children saw a film in which an adult “model” beat up and shouted at a Bobo doll in highly specific ways. The film was the same for all the children except for the ending: one group saw the model rewarded (praised) for doing a good job of beating up Bobo, one group instead saw the model punished (scolded) for beating up Bobo, and one group saw the model experience no consequences.
Next came what was called the performance phase of the experiment. Each child was allowed to play with a Bobo alone and the question was how many of the model's behaviors the children would imitate. So far, no surprises. Children who had seen the model punished imitated few behaviors; children who had seen the model either be rewarded or experience no consequences imitated significantly more.
Finally came the learning phase, in which each child was offered rewards for imitating the model's behaviors. Surprise: the differences between the groups disappeared and the children all imitated the behaviors at a high level. That is, all the children had learned how to mistreat Bobo in detail; the ones who saw the model punished simply didn't display this learning until the right time, when there was an incentive for doing so instead of — in their minds — the possibility of punishment. An important implication of this experiment and many related ones that followed is that when children watch violent television shows and movies, it doesn't much matter if the “bad guys” get it in the end. Children (and adults) still learn how to commit violence and aggression. Later, they may use this learning if the occasion seems to warrant it, especially if they don't think they will be caught and punished.
Elements of a Good Experiment
Psychological experimenters must attend to certain principles and adhere to fairly specific procedures. Otherwise, the results may be difficult if not impossible to interpret or may not be meaningful. The following is a partial list of important considerations in conducting experiments, using Bandura's experiment for reference:
Participants are typically randomly assigned to experimental conditions in the hope that each group will be equivalent in any important respects. Bandura randomly assigned children in the hope that the groups, overall, would be equivalent in aggressiveness.
Each group has exactly the same experiences except for differences in the experimental conditions. In Bandura's experiment, all the children saw the same film except for the ending.
If the groups aren't equivalent and treated the same except for experimental conditions, the result is confounding — something other than the conditions might instead be responsible for the results. For example, Bandura's experiment might have been confounded if one group saw the film in the morning and the others in the afternoon, because the afternoon groups might be tired and pay less attention.
What happens in an experiment must be relevant to the topic under study. The term for this is operational definition, and it was reasonable for Bandura — in studying aggressive behavior and imitation — to define these as exposure to an aggressive model and the extent to which the children beat up Bobo.
Operational definitions also determine the extent to which an experiment reflects what happens in the real world, which is called external validity. Most would agree that Bandura's definitions and results shed light on children's observational learning of aggression that might apply to many real-world settings.
Even when these considerations are followed, no researcher should make sweeping generalizations based on a single experiment. We can only say that children learn aggressive behavior through observing it because many others have replicated Bandura's experiments. That is, similar studies have been conducted with different children, in different settings, with different procedures, and with various other forms of aggressive behavior.