Boosts vs nudges: perceived effectiveness and criticism shape preferences for sustainable behavioural policies

• People's preferences between energy nudges and boosts were measured experimentally (n = 253). • Participants viewed boosts more favourably but preferred nudges. • People associated perceived cognitive/time costs with boost, and autonomy violations with nudges. • Policy criticism influenced preference direction but less than perceived or communicated effectiveness. • Effectiveness messages were less likely to shift preferences if they contradicted prior effectiveness perceptions.