Disinformation presents a major threat to political stability as it propagates unsubstantiated beliefs and undermines the quality of public debate. To safeguard citizens against disinformation, there has been a rapid rise in online fact-checking and verification. Globally, such initiatives have gained support from a wide range of policy actors, media outlets, and technology developers. However, the effectiveness of these countermeasures remains open to question. Empirical research indicates that corrections are ineffective for certain demographic groups and may even reinforce or amplify false information. In addition, the assumption that disinformation may be countered through exposure to correct information fails to address the broader political, technological, and societal factors that underpin post-truth culture. In this paper, we argue that countermeasures which encourage citizens to reflect on the information they consume and choose to share is likely to be more effective than authoritative corrections. We test this assumption by investigating whether the provision of contextual information (i.e. about individual pieces of content and about individual’s personal consumption habits) can influence strength of belief in disinformation claims and willingness to share disinformation among peers. This is tested through experiments in which subjects are asked to evaluate political disinformation on social media and are assigned to treatments with and without the contextual information treatments. The effectiveness of the treatment is analysed in terms of the subjects’ ideological identity, political knowledge, and trust. Our findings contribute to a deeper understanding of the factors influencing citizens’ willingness to share political disinformation and to the development of more robust countermeasures. This research is undertaken as part of a European Commission H2020 project on countering disinformation (grant number 825227).