Psychological research often relies on participants selecting the type of study they wish to join, which may inadvertently create a self-selection bias. Recent investigations have shown that individuals attracted to psychological studies may exhibit more symptoms of personality and affective disorders compared to the general population. This raises questions about the generalisability of psychological study findings and the need for modifications in recruitment strategies. The findings were published in the journal PLOS One.
In a study involving 947 participants, researchers examined whether the type of invitation (to discuss recent critical or regular life events) or the source of data (face-to-face or online) attracted individuals with varying levels of psychopathology. Findings revealed that participants who applied for paid psychological studies exhibited more symptoms of personality disorders than those who had never applied for such studies.
Modern psychological research has increasingly relied on online data collection methods, offering rapid access to large numbers of participants. While online samples have been found to be generally similar to offline samples in terms of internal motivation and extraverted behaviours, some evidence suggests greater levels of depression and social isolation among online participants.
The study aimed to investigate self-selection bias in relation to personality disorders among participants of different types of studies. Researchers analysed personality disorders using both dimensional and categorical models, as well as measuring borderline personality organisation. The project sought to determine whether the type of invitation or source of data attracted participants with different or deeper personality disorders and compared these groups to individuals who had never participated in psychological studies (non-volunteers).
Results showed that participants who responded to an invitation for a study on a negative critical life event and its psychological consequences displayed not only more personality disorders but also a higher number of symptoms for various types of disorders compared to those who volunteered for a study on a regular life event and non-volunteers. Furthermore, all volunteers, regardless of the experimental group, exhibited higher levels of personality psychopathology, suggesting that people with the healthiest personality structure may not be commonly included in research samples.
Researchers propose three solutions to address this issue: alternative recruitment strategies targeting participants who have not participated in research before, engaging more general samples than typical psychology student samples, and controlling for potential psychopathologies with measures like the DSM-5 Brief Form. These practices could help increase the accuracy and trustworthiness of psychological study findings.
The study’s findings highlight the need for researchers to consider the impact of recruitment strategies and the type of research itself on potential psychopathologies among participants. It is recommended that either recruitment strategies are modified or greater caution is exercised when generalising results due to this methodological concern.