The way in which researchers recruit participants for psychological studies may influence the results. European researchers state this in PLOS ONE.
Izabela Kaźmierczak et al put various advertisements online to find out which people respond to different types of paid surveys. In addition, they actively approached people who had never participated in psychological research with financial compensation. The research shows that both the recruitment text and the method of data collection – through personal interviews or online questionnaires – influence which people participate in a survey.
Online participants scored higher on depression and anxiety than people who had never participated in research. In addition, people who self-enrolled for paid psychological assessments were more likely to have symptoms related to personality disorders than people who had never self-enrolled. This may lead to an over-representation of people with personality disorder symptoms in psychological studies.
Because personality disorders, according to the researchers, are associated with rigid beliefs and inflexible behavioral patterns, this can also influence studies that try to bring about behavioral change, for example. But also on studies that identify and/or describe psychological phenomena.
The researchers advocate adapting recruitment strategies for psychological studies, or being more careful about generalizing results of psychological studies to the general population.