This study analyses how information provided by different types of interest groups influences the ability of members of parliament (MPs) to accurately perceive the preferences of those citizens who voted them into office. To study how information provision by interest groups affects MPs' perceptions, we combine unique data from a citizen survey and face-to-face meetings with 151 federal MPs in Switzerland, thus enabling a comparison of actual voter preferences with MPs' estimations of these preferences. Ties to citizen groups, as revealed in a survey, relate to more accurate perceptions by MPs, even when controlling for MPs' partisan affiliation. Ties to business groups, as revealed in the official registry, relate to less accurate perceptions. These findings suggest that interest groups can both tighten and weaken MPs' link to their party voters, which might have repercussions on substantive representation and democratic accountability.