The applicability of the inclusion/exclusion phenomenon to organ donor registration

Organ donor rates in Australia consistently fail to meet demand. Organ donor registration can be made either by a blanket, cover-all question or by having the citizen select organs from a list. The inclusion/exclusion phenomenon has shown in other domains that when a person is in a situation where they are excluding items from a list, their resulting list is longer than if they are including items to a list (Kogut, 2011). We investigated whether this classic phenomenon could be exploited to increase organ donation rates. Using a 2 (opt-in, opt-out) x 3 (blanket, inclusion, exclusion) between-subjects design, we tested whether different registration conditions influenced (a) absolute donation (i.e., willingness to donate something), and (b) the number of organs donated. 141 participants (age M = 27.7 years, range: 18 - 73, female = 108, nonbinary = 1) were randomly allocated to one of the six registration conditions. The exclusion approach, involving having the list pre-ticked, elicited more organs donated than the inclusion approach currently used in Australia. Individual difference measures indicated that participants' feelings of attachment to organs and fear of having the body damaged after death also influenced the number of organs donated. The inclusion/exclusion phenomenon relies on items with a low evidentiary threshold being left in under exclusion and left out under inclusion. We suggest that feelings of attachment form this evidentiary threshold.