Behavioral experiments

Human beings don't see the world as it is. Everybody 'filters' what they see. Our thoughts & beliefs shape the way we see and interact with the world. For example:

Lucy experienced a lot of violence from men when she was growing up. She came to believe that "all men are violent". By the time she is an adult her filters have got very good at trying to keep her safe - by detecting violence, especially violence by men. Unfortunately, her filters aren't very good at 'letting through' examples of some men being gentle and kind - so Lucy finds it difficult to see this. As a consequence she doesn't feel very safe a lot of the time, especially when there are men around.

Beliefs are often more like opinions than facts. Behavioral experiments are a way of testing our beliefs, instead of letting them filter the world for us.

Types of behavioral experiment

There are many different kinds of behavioural experiments. All have the same purpose - they all allow you to explore or test the truthfulness or a belief. This may be an old belief that you have had for a long time, or a new belief that you don't feel sure about.

Data gathering - surveys

Surveys are a quick way of gathering opinons from a lot of people. They help us to compare our beliefs against other people's honestly-given opinions.

E.g. Dana believed "other people will think I'm disgusting if they see my surgery scar" very strongly (95%). She and her therapist took a picture and decided on a quick survey question "What would you think about a person if you found out they had a scar like this?". Together, Dana and her therapist asked for people's answers to the survey questions. Dana was surprised to discover that most people would not think anything of the scar. Her rating of her original belief dropped significantly (40%).

Hypothesis testing - trying something out

Another way of testing a belief is to conduct an experiment - in the same way that a scientist does an experiment to test a hypothesis.

E.g. Dana's therapist encouraged her to test her beliefs in the real world. Dana still believed that if she showed her scar to people that most would react with disgust. Dana realised that the only way to find out if her belief was true would be to show her scar to people and to gauge their reaction. She decided that she would show her scar to 10 people to make it a fair test. She predicted that at least 5 would react with disgust, and that she would be able to tell this by looking at the expression on their faces.

Steps in carrying out a behavioral experiment

We can approach our beliefs like a scientist approaching a new discovery.

Step 1: Identify the belief to be tested

What is the belief that you have identified that you want to test? Write it down in a single sentence. Examples might include:

  • "I can't eat in-front of people - if I do they'll think I'm disgusting"
  • "If I make eye contact with people I'll be attacked"
  • "If I don't check the door locks ten times before I go out I'll leave the house unlocked"

Step 2: Rate the strength of the belief

How strongly do you believe this statement? Rate it from 0% (not at all) to 100% (completely, with all my heart).

Sometimes it can be helpful to give separate ratings for how much you believe it with you head (logically), and how much you believe it with your heart (emotionally)

Step 3: Plan an experiment that could test the belief

How might you test this belief? When scientists test a hypothesis they try to plan an experiment which could prove their hypothesis to be false.

Remember to plan what you're going to pay attention to.

Think about how many times you might need to repeat the experiment. One result could be a fluke, and you may need to carry out the experiment a number of times to get a fair reflection of the truth.

Step 4: Identify any obstacles that could make it difficult to carry out the experiment

Is there anything that could get in the way of doing the experiment? If you need people to be around to help you, who could you ask? If it can only be done in a certain place, when can you go there? Do some problem-solving to work out any issues.

Step 5: Carry out the experiment

This is the part that will require courage. You may want to have someone with you who can encourage you, and who can remind you why you're doing this.

Step 6: Record the result

Every good scientist records what happened.

Step 7: Re-rate how strongly you believe in the original belief now

Once you have done the experiment go back to your original belief. Read it to yourself and then re-rate how strongly you believe in it now.

Behavioural experiment worksheets

Behavioral Experiment

Behavioral Experiment Planning

Use this to plan and carry out behavioural experiments

References & further reading

Bennett-Levy, J., Butler, G., Fennell, M., Hackmann, A., Mueller, M., & Westbrook, D. (Eds.). (2004). Oxford guide to behavioural experiments in cognitive therapy. Oxford University Press.

For more information see the Behavioural Experiments page on PsychologyTools