20 May 2025
Bilbao Campus
We know that both resource scarcity and expectations of effectiveness influence people’s preferences and decisions in healthcare. But how do these two factors (scarcity and expectations) interact when combined? Why, for example, were certain patient groups—mainly older adults and those with disabilities—so evidently discriminated against during the COVID-19 pandemic, when medical resources were particularly scarce?
Aranzazu Viñas and Helena Matute, researchers at the University of Deusto, together with Fernando Blanco from the University of Granada, sought to answer this question in order to better understand the mechanisms involved in decision-making during times of scarcity. The results of their research have been published in the journal "Scientific Reports".
In the two experiments described in the article, volunteers were asked to imagine they were doctors tasked with treating a series of fictional patients. Participants were randomly assigned to two groups: one with scarce resources (though sufficient to treat the patients) and another with abundant resources. Next, all participants were presented with a series of patients to whom they could choose to apply a treatment or not. These patients were labelled as either highly sensitive or minimally sensitive to the treatment, which created expectations of high or low effectiveness. Immediately after each decision to apply or withhold treatment, participants were informed whether the patient recovered or not.
It is important to note that the labelling was inaccurate and that both patient groups actually had the same likelihood of recovery. In the first experiment, the treatment was effective, meaning that administering it always increased the patients’ chances of recovery. In the second experiment, not only was the patient labelling incorrect, but the treatment was also completely ineffective in all cases, offering no increase in the likelihood of recovery.
At the end of both experiments, participants were asked whether they believed the treatment was effective and if it was more effective with one of the patient groups. The aim was to determine whether, despite the prior expectations induced by the labelling, participants were able to learn from the evidence they received throughout the experiments, which contradicted the labelling. In all cases, participants had the opportunity both to prove the classification wrong and to discover the true effectiveness of the treatment simply by observing the patients’ recoveries.
The results showed that participants administered less treatment to patients who were (incorrectly) classified as less sensitive, especially when resources were scarce. Furthermore, participants judged the treatment to be less effective for these patients, even in Experiment 2, when the treatment was completely ineffective for everyone! In other words, their prior expectation, induced by the incorrect labelling, led participants to allocate resources unfairly and also interfered with their ability to learn that the treatment was equally effective (in Experiment 1) or equally ineffective (in Experiment 2).
Ultimately, the scarcity of resources combined with prior expectations induced by systems that can sometimes be flawed may lead to an unfair distribution of resources, the misuse of treatments that are not truly effective, and, even more concerning, a reduced ability for people to learn from evidence and thereby correct their mistakes.
Source : Vinas, A., Blanco, F., & Matute, H. (2025). The combined effect of patient classification and the availability of resources can lead to biased perception of treatment effectiveness. Scientific Reports, 15, 15915. https://doi.org/10.1038/s41598-025-01043-w
