Understanding Psychology at A level and GCSE: 4

Here is the fourth in our new series of Psychology blogs – useful for anyone revising for exams or thinking about taking up Psychology as a new subject at A level or GCSE.

Why do Psychologists do Experiments?

As we said in our second blog, psychology is not an exact science.  Psychologists develop theories on why they think things happen, or why people behave in the way they do. They will then conduct experiments to test their theories.

Psychologists carry out experiments to either support or disprove the theories they propose.  They may do these experiments in a range of different ways –

  • in a laboratory
  • by observing people in their natural settings (field experiments)
  • conducting surveys
  • using data from questionnaires
  • comparing case studies (where one or a small group of people are studied)

(We will learn more about the different methods of carrying out psychological research in later blogs.)

However, it is important to note that the method of testing can itself have an affect on the results obtained.

For example, the American psychologists, Elizabeth Loftus and John Palmer had a theory that information given after an event could affect a person’s memory of an event. This was an important theory because it suggests that when a person witnesses a crime or important event, information given afterwards can affect their memory of that event.

In 1974, they studied 45 students at Washington University. They showed the students videos of seven traffic accidents. After each video, the students were asked to write an account of what they had just seen. They were also asked questions. The key question they were asked was how fast the vehicles were going when they had the collision.

There were five conditions (or groups) in the experiment.

Group A were asked –

“About how fast were the cars going when they smashed each other?”

Group B were asked –

“About how fast were the cars going when they collided with each other?”

Group C were asked –

“About how fast were the cars going when they bumped each other?”

Group D were asked –

“About how fast were the cars going when they hit each other?”

Group E were asked –

“About how fast were the cars going when they contacted each other?”

They found that students who were told the cars “smashed” into each other gave the highest estimate of speed. They estimated –

Smashed             40.8 mph (mean of the group)

Collided                38.3mph (mean of the group)

Bumped               38.1mph (mean of the group)

Hit                          34mph (mean of the group)

Contacted           31.8mph (mean of the group)

These results showed that how the question was phrased affected the students’ estimates of how fast the cars were going. Those told that the cars “smashed”, gave the highest estimate of the cars speed. Those told that the cars “contacted” gave the lowest estimate. But all participants saw the same videos. So what affected their estimates of speed was the word used in the question – smashed, collided, bumped, hit or contacted.

Loftus and Palmer conducted a range of experiments like this one. They mainly found that information given after an event can affect a person’s recall of that event. Using  a series of experiments (not just one), they proved their theory.

However, that’s not the end of the story. Another psychologist may now come along and carry out a group of experiments that finds different results.  That is why psychology is not an exact science, and there are no right answers about humans and animals.

So we have seen that psychologists conduct experiments to test their theories about human behaviour; that the test itself can affect the results of their experiment, and that the results are not exact but general. That is what makes psychology such a wide subject and such an interesting one – there is a lot to learn about human beings.

This is what makes psychology so fascinating.

Tracey Jones

Psychology Tutor – Oxford Open Learning

See more by

Stay Connected