This thesis examines how the design of messages affects the extent to which individuals
comply with requests or requirements from public actors. More specifically, it presents results
from seven field experiments on changing messages sent to the public and professionals as part
of routine public sector activities: issuing requests for overdue tax payments, sending reminders
for upcoming hospital appointments, and providing antibiotic prescribing feedback to general
practitioners. These are all cases where non-compliance can create harm or inconvenience to
others.
The trial messages are constructed to test the two main approaches to increasing compliance:
one, ‘deterrence’, sees individuals as utility maximizers who are concerned solely with
advancing their private interests, and who respond only to the threat of sanctions; the other,
‘non-deterrence’, claims that compliance is influenced by factors such as social norms,
perceptions of fairness, ethical concerns, and the provision of public goods. I attempt to
increase the impact of both approaches by applying concepts from behavioural science, such
as framing effects and the omission bias.
The results indicate that deterrence-based messages consistently increase tax compliance,
sometimes to a substantial extent. Non-deterrence messages also can increase compliance with
both healthcare and taxation policies, although the effects are sometimes small. The largest
effect sizes for non-deterrence approaches came from social norm messages. Non-deterrence
approaches may be more effective for populations who had previously been compliant.
Importantly, I provide evidence that both deterrence and non-deterrence messages can be
enhanced through the application of concepts from behavioural science.
These trials strengthen the limited evidence base on the real-world effects of messages intended
to increase policy compliance. They demonstrate that compliance may depend on specific
choices about how messages are constructed and delivered. In the process, they show how
behavioural science offers a useful framework for governments making these important
choices.