While museum educators are essential to engage under-served publics in science, their communication often reinforces dominant cultural norms and disengage visitors. Why are certain communication models so dominant and why are the cultural norms that underpin these so resistant to reconceptualisation? What conceptualizations about science communication are held by museum coordinators and how representative are they of the real practices? We explored these through an interpretative phenomenological approach in the context of a mobile museum with a social justice agenda. The analysis of museum coordinators’ and museum educators’ narratives, through the perspective of Idealized Cognitive Models (ICMs), shows that coordinators hold two dichotomous ICMs: a dominant deficit model and a non-dominant participatory ICM. The data from museum educators, however, indicate the coexistence of blended practices, which attempt at establishing dialogue, but fail to align with the participatory model. This shows the difficulty in reconceptualising the deficit ICM, as it is deeply rooted in long-standing enlightenment project of museums and reinforced by organizational factors.