Knowledge is lacking on the choice and use of representations in a design process when seeking to investigate user experiences. Two types of representations (a storyboard and an interactive prototype) of the same system were used in a user experience evaluation involving 24 participants to investigate how different representation formats influence participants' responses to interactive systems. Data from a questionnaire and individual interviews were compared. Very few differences in questionnaire responses were found. However, the interactive prototype gave rise to more design proposals as well as more personal reflections on experiences although with a focus on interface design details. The storyboard elicited more responses on the core ideas of the concept, but less grounded in reflections on personal use. The differences are attributed to how each representation managed to convey interactivity and context, resulting in differences in experienced agency. It is therefore suggested that there is a need for further research, but with less focus on the type of system representation and more focus on how the content and affordances of system representations can be designed to elicit rich and personal reflections on user experience in early design phases.