Throwing Scottish independence into the electoral debate benefits the SNP and penalises the Labour, according to a study by the European University Institute conducted at the University of Edinburgh.

When the three main Westminster parties – Conservatives, Labour and Lib Dems – directly attack the SNP and make explicit reference to the issue of independence in their electoral arguments, Scottish voters are more likely to vote for the SNP, instead of stepping away from it. On the other hand, framing the electoral competition in relation to Scottish independence slightly reduces the support for Westminster parties, and especially for the Labour, among Scottish voters. The results of the study, however, suggest that these “lost” Labour votes do not go directly to the SNP, but mostly to other parties, including the Lib Dems and the Green party.

The study, financed by the European University Institute, was conducted online with a pool of subjects recruited by BLUE Lab, University of Edinburgh between 22 and 30 April. Participants were randomly assigned to two conditions. In the first one, they were asked to read 4 short texts including party leaders’ statements supporting the Conservatives, the Lib Dem, the Labour, and the SNP. In the second condition, the participants read the same arguments, but each text contained an additional paragraph in which the issue of Scottish independence was made salient by framing the electoral competition as a challenge against the SNP.

Another finding indicates that when the Labour and the SNP are in direct opposition, the electorate polarizes, since Labour and SNP voters become more far apart, and Labour voters are less likely to vote strategically for the SNP. On the contrary, when the issue of independence is kept out of the debate, those who intend to vote Labour are more favourable towards the SNP, and, at the same time, those who intend to vote SNP are more favourable towards the Labour.

Finally, results show that making Scottish independence salient in the electoral debate increases Scottish voters’ support for leaving the UK. This applies not only to the general pool of participants, but also to Labour voters, who become more favourable towards a separated Scotland when their party leaders explicitly frame Labour as a unionist party.

According to Davide Morisi, PhD researcher at the European University Institute, “the results from this study indicate that framing the electoral competition in direct opposition to the SNP can be counter-productive for the main Westminster parties, since the support for the SNP increases instead of decreasing.

Making Scottish independence a salient issue penalises particularly the Labour, because voters perceive it as closer to the other unionist parties, therefore they are more likely to cast their vote for other parties. In addition, the fact that Labour voters become more favourable towards a separated Scotland when their party takes an explicit unionist positions indicates a growing discrepancy between the Labour and its Scottish supporters. These trends suggest that reconciling a “Scottish Labour” with a “British Labour” might prove an extremely complicated task especially in the case of an unfavourable electoral outcome for the Labour”.