Electrostatic potential energy is a topic of great difficulty for many students. In this paper, we empirically test the utility of two approaches for laying a foundation for developing an understanding of energy in an electrostatic context, with interdisciplinary relevance. We examine student responses to a question about how the potential energy of a system of two attracting ions varies with distance (the "ions" task), and investigate how these responses change after students have been exposed to either a question designed to help them think about gravitational potential energy or the potential energy of a system of two attracting magnets. We found that performance on the ions task improved for those students who were prompted to think about the gravitational context, while it did not change for those who considered the magnets. The results are interpreted using dual-process theories of reasoning and decision making, and implications for instruction are discussed.