Trust in interpersonal (informal) information: Respondents' agreement with two statements (Table S1 ). Responses were made on categorical five-point scales ranging from ''strongly disagree'' to ''strongly agree''. Scalability of these two items was assessed using Cronbach's alpha, which at 0.50 indicated that scalabilty was unsuitably low for two items. This suggests that these two items measure different aspects of social information. Again to minimize potential measurement error this construct was treated as a latent variable in the subsequent analysis.