Leanne Byrom, a freelance UX practitioner and UX lead for Phosphor Digital, writes about the importance of mental models in UX design:
Designing something right requires that you completely understand what a person wants to get done. You need to understand how a person uses something if you’re going to get the design right for them. You also need to know the person’s goals and the procedures she/he follows to accomplish those goals.
Mental models give you a deep understanding of people’s motivations and thought processes along with the emotional and philosophical landscape in which they are operating.