Research carried out by Aranzazu Vinas (University of the Basque Country), Helena Matute (University of Deusto, Bilbao), and Fernando Blanco (CIMCyC - University of Granada) shows that financial incentives are not always effective. If we want to develop scientific thinking, it is better to give a simple explanation than to offer a financial reward.
People are very good at detecting cause-effect relationships. This ability helps us understand the world, learn, make decisions, or predict the future. In short, it helps us adapt and survive. In fact, we are so good at it that we often find connections that do not actually exist. As a result, we fall into the so-called causal illusion, that is, we mistakenly believe that one event is the cause of another, when in reality both are independent.
To avoid this type of error, it is important to develop scientific thinking, which is based on establishing cause-effect relationships based solely on evidence. But how can we do this? We could increase people's motivation, for example, by offering them a reward if they detect a relationship correctly. Or we could teach them to think like scientists, providing them with adequate information to solve problems in which there may (or may not) be cause-effect relationships.
To evaluate the effectiveness of the two previous options, three experiments were conducted. In the instructions, participants were told to imagine that they were doctors and were presented with a series of fictional patients to whom they could administer treatment or not. Immediately after making their decision, they saw whether or not the patient was cured. At the end, participants were asked to indicate how effective they thought the treatment was. It is important to note that the treatment was not actually effective, as patients were cured at the same rate regardless of whether they followed the treatment or not.
In the first two experiments, half of the participants were offered a financial reward if they answered correctly, while the other half were offered nothing. The results showed that both groups developed causal illusion to the same extent. In other words, the reward did not serve to reduce the illusion.
In the third experiment, half of the participants were given an explanation indicating that people tend to develop causal illusions and that, in order to avoid falling into this error, it is important to evaluate all available information, both what happens when the cause is present and what happens when it is not present (i.e., they were explained how to think scientifically). Meanwhile, the other half were not given this information. This simple explanation did serve to significantly reduce causal illusion, although it was not enough to eliminate it completely.
In summary, this research confirms that causal illusion is a common error that is difficult to eradicate completely. However, it also shows that we can help people think more scientifically and, as a consequence, reduce causal illusion. To do this, it is more effective - as well as cheaper - to explain how to evaluate the available information than to offer financial rewards to increase motivation. Even a simple written explanation can make a difference.
Reference
Vinas, A., Blanco, F., & Matute, H. (2025). Reducing the causal illusion. A question of motivation or information? Royal Society Open Science, 12. 250082. https://doi.org/10.1098/rsos.250082
Contact at the CIMCYC
Fernando Blanco (@email)