This document discusses how allowing dynamic interaction (the ability to revisit inputs and reconsider solutions) with decision support tools can impact users' perceptions and decision making. It first reviews literature on decision support mashups and dynamic interaction. It then proposes hypotheses about how increasing dynamic interaction could increase the perceived diagnosticity (usefulness) of the tool and user confidence. An experiment is designed to test these hypotheses. The results suggest dynamic interaction increased perceived diagnosticity and confidence, and may also improve decision quality.