Why are immigrants from former communist regimes less likely to support left-of-centre parties than other immigrants? The literature finds recurring empirical evidence for this pattern, but the mechanism underlying this behaviour remains largely unexplained. In this article, I test two theoretical approaches: Immigrants from former communist countries might have particularly high economic aspirations and believe that left-wing policies hinder their own economic success. Conversely, immigrants might turn against the political left due to resentments against parties with a similar ideology as the former communist dictator. To test these mechanisms, I conduct a blocked-randomised experimental online game. The two treatment settings simulate a socialist and capitalist economy to assess the preference for the corresponding regime. Participants are asked to complete tasks, which let them score points based on effort and skill. Depending on the treatment setting, the total points made in each group are either redistributed between all group members equally (socialist setting) or participants keep the score they have individually achieved (capitalist setting). Ideological bias appears if immigrants from communist regimes are less likely to favour the socialist rule system compared to other immigrants, even if they benefit from it. On the other hand, immigrant groups behaving equally across both treatment settings supports the considerations of economic aspirations. By conducting this experimental online game, I do not only contribute to the theoretical understanding of the effect of political socialisation in the case of immigrants, but also propose a novel approach on how to measure political preferences.