This paper investigates the effects of physical objects as support for imagination in the context of enactive storytelling. More specifically, we target nine-year-old children because of their general disengagement from creative activity, a phenomenon known as the Fourth-grade Slump that arises from a demotivational spiral brought on by social awareness. We study how enactment using physical objects may allow the child to better engage in story imagination. Our study compares the richness of the imagination under three main enactment conditions with objects that have varying degrees of fidelity to referent objects: Cultural objects (physical visual resemblance); Physical objects (similar physical affordances); Arbitrary objects (minimal physical and visual affordances). We employ a mixed-methods analysis to gauge the child's level of broader imagination from three data sources: Enactment videos, drawings and interviews with the children. We found that the object types significantly differ in their support of the imagination, with the object of highest specificity being most effective. Our findings can inform the design of embodied creativitysupport systems for children.