This data set contains two experimental studies, the studies investigated how perceived information sources would affect readers' decision making about belief and feeling while they read tweet texts. In the behavioural study, we aimed to validate stimuli that were then used in the fMRI experiment. We examined our hypothesis that tweet texts accompanied by more often used information sources of individuals (i.e. the logos of media) would significantly increase the degrees of their belief about the texts, compared with tweet texts accompanied by the information sources that they never used. In the fMRI study, we hypothesised that perceived information sources would modulate one's decision-making on belief and feeling about tweets, and that the process would involve social emotional brain regions.This collaborative project between the Neuropolitics Research Lab (NRlabs), at the University of Edinburgh and Full Fact, the UK's independent fact-checking organization, employs neuroscientific, psychological and behavioural insights to help us to understand what makes Brexit-related claims spread on digital platforms. Using cutting edge scientific techniques in big data analysis this project offers new insights into how citizens' expectations on Brexit and its consequences are shaped in an increasingly digital world. It will inform organisations on how to communicate what is often dry and complex information related to Brexit in a credible, trustworthy and memorable way using digital communications. These insights will be essential for the strategic management, implementation and public communication of the Article 50 process for the UK's withdrawal from the EU. The question of what constitutes a fact (or an alternative fact) has perhaps never been more salient in public debate. The thirst for 'facts' during the Brexit referendum campaign was a key feature of public debate as was the question of whose facts count. The role of experts in the delivery of factual information came under close scrutiny and became a substantive feature of campaign dialogues. The question of trust and authority in information transmission has been under serious challenge. Citizens' expectations of Brexit and its consequences are, at least in part, shaped by their evaluation of the facts - but how do they decide what is a trustworthy fact? What factors lead them to imbue some sources of information with greater authority than others and under what circumstances do they choose to engage with, share or champion certain 'facts'? How does the context in which 'facts' are disseminated shape the expectations of the citizens on Brexit? Digital technology and online communication platforms such as Twitter and Facebook, play an increasingly important role in the public communication of both information and misinformation. To date, however, we have little information on how 'facts' transmitted in these digital platforms are internalized by recipients and on how this information impacts on citizens' expectations. We investigate how membership of a specific social media bubble impacts on the evaluation of the information received; how the status of the sender or even the content of the communication (whether it contains an image or a web link) matters; and how the nature of the information received, confirmatory or challenging of previous knowledge, impacts on fact transmission to different publics. This project builds on the extensive engagement of two research teams on Brexit-related research and with the UK in a Changing Europe team. Both teams are engaged at the highest level in stakeholder engagement and the project is built on a co-production model, ensuring that the issues addressed are of direct interest to those most likely to utilise the insights developed directly in their daily work. The project is designed in close collaboration with stakeholders to ensure that it can adapt swiftly to maintain relevance in the fast-moving Brexit environment. The project has access to a unique social media data-base of over 40 million tweets that NRlabs has collected on the Brexit debate since August 2015; the cutting edge skills and facilities for conducting experimental research at NRlabs; and ensures daily policy relevance through Full Fact's engagement, nationally and internationally, in the fact checking environment. The contribution of this project addresses the very heart of the mission of the UK in a Changing Europe programme - to be the authoritative source for independent research on UK-EU relations, underpinned by scientific excellence and generating and communicating innovative research with real world impact.

The data were acquired from experimental studies. We invited healthy volunteers for all studies. Behavioural pilot study (N=43) was conducted using a computer based experiment, where we collected ratings and reaction times from participants. fMRI study (N=35) collected MR brain images while participants performed the tasks that were used in the behavioural study.