• Population-representative survey data from 11 European countries and the USA. • Context-specific orientations play a decisive role for individuals' affective feelings. • Affective feelings exert a strong influence on the support for public mega projects. • Effortful processing filters the influence of affective feelings on decisions. • The filtering mechanism, however, is rather ineffective. When facing complex decisions, individuals often employ heuristics, relying on affective feelings rather than systematically evaluating decisional pros and cons. If this heuristic misguides the personal decisions, the consequences may be unfortunate for the individuals but not harmful to the wider society. This is not the case, however, for decisions with a public policy impact, such as the approval of public mega projects, which can result in inefficient government spending. This study thus examines the formation and interplay of cognitive versus affective decision components in the context of these projects. More specifically, using population-representative survey data from 11 European countries and the US, the authors provide evidence for three major findings: First, context-specific orientations play a more decisive role for individuals' affective feelings than their general orientations. Second, affective feelings exert a strong influence on their support for public mega projects. Third, although effortful processing filters the influence of affective feelings on decisions, the filtering mechanism is rather ineffective. [ABSTRACT FROM AUTHOR]