Offering male endoscopists as decoy option to nudge disinclined women to have colorectal cancer screening.

Previous studies have shown that a large proportion of women invited for bowel cancer screening prefer endoscopists of the same gender. We tested whether women who are initially disinclined to undergo flexible sigmoidoscopy screening would be more willing to have the test with a female practitioner if they were also offered a decoy appointment with a male practitioner. We conducted two online experiments with women aged 35-54, living in England, who did not intend to undergo flexible sigmoidoscopy screening. In both experiments, women were randomised to two conditions: (1) control (appointment with a female endoscopist) and (2) decoy (two appointments to choose from, one with a male endoscopist and one with a female endoscopist). Experiment 1 (N = 302) verified the conditions for the decoy using a conventional intention scale, while experiment 2 (N = 300) tested how the presence of the decoy influences the likelihood of women choosing the appointment with the female practitioner in a discrete choice task. While experiment 1 showed that the presence of the decoy increased intentions to attend the appointment with the female practitioner (p = 0.02), experiment 2 confirmed that women were more likely to choose the appointment with the female endoscopist if they were also offered the decoy (p < 0.001). In both experiments, the presence of the decoy decreased perceived difficulty of the screening decision and cognitive effort required to make the decision. Offering disinclined women a male practitioner increased intention to have the test with an endoscopist of the same gender. This suggests that male screening practitioners can be used as decoy options to increase the likelihood that women choose female practitioners and facilitate the screening decision.