THE IMPACT OF THE “ILLUSION OF EXPLANATORY DEPTH” ON HEALTH-RELATED DECISION MAKING PREFERENCES

Purpose: As patients are encouraged to become more involved in their healthcare decisions they may be confronted with how little they actually know about the decision options. People often think they have a relatively good understanding of how something works, a phenomenon known as the “illusion of explanatory depth”, an illusion that is disrupted when people are forced to try to explain how it actually works (see Rosenblit & Keil, Cogn Sci,2002). Whether people exhibit the illusion of explanatory depth for medical interventions and the impact of disrupting this illusion on interest in using or being involved in decisions about using those interventions is unknown.

Methods: Participants (N = 309) were recruited through Amazon’s Mechanical Turk to complete an online survey experiment. Participants began by indicating the perceived effectiveness of a 12 medical interventions (preventative medicines, screening tools, and treatments) and their subjective knowledge about how the medical interventions work. Participants were then randomly assigned to explain how one of the medical interventions worked. After providing their explanation, participants re-rated their subjective knowledge and perceived efficacy of the medical intervention, as well as their willingness to use and be involved with making a decision about using the intervention. After completing this process for a second medical intervention, participants indicated their familiarity and usage of each prevention, screening tool, and treatment.

Results: Overall, participants exhibited a decreased sense of understanding after attempting to explain how a medical intervention works (p < .001), providing evidence for the illusion of explanatory depth. Perceived efficacy of the medical intervention also decreased after providing an explanation (p < .001). More importantly, decreases in perceived efficacy were associated with decreased willingness to use the medical intervention (p < .001) and decreased desire for participation in decision making about the medical intervention (p = .01).

Conclusion: Disrupting the illusion of explanatory depth for medical interventions was associated with decreased interest in utilizing the medical intervention and less desire for involvement in decisions about whether to use the medical intervention. While disrupting the illusion of explanatory depth may reduce a patient’s interest in being involved in the decision-making process, it could be used as a tool for correcting misinformation or reducing the overutilization of low-value services.