How interest groups affect MPs’ perceptual accuracy: evidence from Belgium, Canada and Switzerland

The capacity of members of parliament (MPs) to accurately perceive their electorate’s opinion constitutes a crucial pathway towards substantive representation. Recent research has shown that exchange relationships between MPs and citizen groups, which defend broadly shared interests, increase MPs’ perceptual accuracy, in both majoritarian (MR) and proportional (PR) representation electoral systems. However, interest groups’ effect on MPs’ perceptual accuracy might depend on a number of contextual factors: on the overlap between the constituencies of parties and interest groups (electoral incentives), the frequency/intensity of exchanges between groups and parties (neo-corporatist tradition) and the availability of direct democratic instruments for interest groups. To test these interactions, we employ a diverse-case method, comparing Switzerland, Canada and Belgium. This allows us to introduce variation in terms of electoral systems (CAN vs CH & BEL), neo-corporatist heritage (CH & BEL vs CAN), and direct democratic institutions (CH vs CAN & BEL), while focusing only on federalist countries. In each country, MPs (N = 216 across the three countries) were asked to assess the share of their party voters in agreement with specific policy statements (e.g. “The pension age needs to be raised to 67”). We also conducted a citizen survey in each country, revealing party voters’ preferences on the very same statements. This allows comparing actual voter preferences with MPs’ (N = 216) estimations of these preferences and thus to measure MPs’ perceptual accuracy. MPs were also asked to indicate those interest groups considered most useful for their parliamentary work, allowing us to approximate the type of interest groups MPs rely on in their parliamentary work.