Interactions between social identity groups can reduce perceptions of threatening out-groups and improve inter-group attitudes. But these interactions have an inevitable side effect: while an interaction may improve attitudes among its participants, the same interaction can increase exposure to out-groups in the proximity of the interaction, leading to increased perceptions of threat among those not participating in the interaction. With such negative externalities in mind, this paper argues that the presence of a large number of out-group members both improves and aggravates native attitudes toward out-groups in the same area, which may, in the aggregate, conceal a hot spot of anti-immigration attitudes. This study examines the effects of interaction and exposure through a series of surveys of native attitudes toward Muslim immigrants in the Netherlands. While the exposure effect was not observed, empirical analyses suggest that brief interactions tend to worsen negative attitudes toward Muslims, possibly due to their physical and religious appearances. This highlights the importance of visual cues in shaping inter-group relations, as these visual cues may prompt natives to sort out interactions based on appearance, hindering efforts to promote inter-group contact between Muslims and non-Muslims.