The current study examined a new spatial integration (SI) task, based on figural rather than linguistic stimuli, to measure the construct of mental modeling ability. Previous tasks conflated linguistic ability with mental modeling ability by requiring sentence processing, which may have contributed to mixed findings with respect to the relationship between mental model ability and working memory capacity (WMC). The figural spatial integration task produced the canonical continuity effect, such that discontinuous items had lower accuracy than continuous items. Furthermore, WMC and visuospatial ability predicted SI task performance, and both were stronger predictors for the continuous condition. The interactions between predictors and task conditions suggest reliance on heuristics and/or rehearsal during performance of the more difficult discontinuous items.