Probabilistic modelling needs specialized tools to support modelers, decision-makers or researchers in the design, checking, refinement and communication of models. Users' comprehension of probabilistic models is vital in all above cases and interactive visualisations could enhance it. Although there are various studies evaluating interactivity in Bayesian reasoning and available tools for visualizing the inference-related distributions, we focus specifically on evaluating the effect of interaction on users' comprehension of probabilistic models' structure. We conducted a user study based on our Interactive Pair Plot for visualizing models' distribution and conditioning sample space graphically. Our results suggest that improvements in the understanding of the interactive group are most pronounced for more exotic structures, such as hierarchical models or unfamiliar parameterisations in comparison to the static group. As the detail of the inferred information increases, interaction does not lead to considerably longer response times. Finally, interaction improves users' confidence.