The deliberate setting of default options has proved highly effective in altering social outcomes. However, assessments of their legitimacy have varied widely. To investigate the role of narratives about psychological causation of behaviors in political attitudes towards defaults, we implemented an online-survey experiment among a large representative sample of adults in Germany. Depending on the treatment, subjects learn in a vignette that the decision-maker followed the default (i) with no further explanation given to the subjects, (ii) because he did not know that he could opt out, (iii) because he consciously supported the default or (iv) because he felt socially pressured to follow the default. Our results show that when the psychological mechanism described is a conscious decision to stick with the default option the public support is as high as in the baseline condition in which no mechanism is given. However, describing unawareness of the possibility to opt out or social pressure as underlying mechanisms significantly reduce public support. Our results are not driven by varying perceptions of the decision maker’s implicit preferences. Rather, people perceive some mechanisms as limiting autonomy more than others.