Offering Lottery Entry as an Incentive for Research Participation Compromises Informed Consent

This paper argues that offering entry into a lottery as an incentive to those who participate in research studies represents a challenge to the principle of informed, coercion-free consent that is considered an essential ingredient of permissible recruitment to studies. This is, first, because information about the chances of winning in this context is normally unavailable to potential participants and, without this, they cannot accurately weigh up the risks and potential benefits of participation. Second, even when this information is available, such an incentive capitalizes, I contend, on the difficulty of weighing up small probabilities, exploiting the fact that people tend to be beset by cognitive biases that make it challenging to make decisions rationally. The resulting conclusion is that we should not view lotteries as more ethical than simply paying participants, when the latter is feasible.