Children often hold intuitive conceptions about natural phenomena that are inconsistent with scientific knowledge. For instance, it is common to believe that bigger or heavier objects sink more than others. Previous studies have highlighted the role of inhibitory control in suppressing intuitive conceptions and learning scientific concepts. However, the variables influencing the level of inhibitory control required to overcome intuitive conceptions remain largely unexplored. This research examines the effects on inhibitory control of two variables identified in the literature: the familiarity of intuitive conceptions and the complexity of scientific concepts. We hypothesized that higher levels of both variables would be associated with an increased need for inhibitory control, while lower levels would correspond to a decreased need for inhibitory control. Four negative priming tasks were designed and administered to children aged 10–12 years. Results indicate that high complexity is associated with a higher negative priming effect, which is representative of increased inhibitory control. Interaction effects suggest it is more challenging to resist a highly familiar conception when the scientific concept is complex to grasp. Our findings contribute to enhancing pedagogical reflections on teaching scientific content that requires inhibitory control.