We propose a new measure for analyzing the structural similarities among the cognitive maps of different decision makers. Upon interpreting the cognitive response elicitation process in the general framework of fuzzy set theory, we are able to develop the similarity measure from straightforward operations on fuzzy relational products. In addition to the mathematical analysis, we present visual representations of cognitive structures and the structural similarities among them. We illustrate the measure's applicability to an empirical dataset collected in an urban planning decision problem, for which the URBS decision support system has been developed to offer information and advice. The key components of the URBS decision support system are the identification and the comparison of the cognitive structures of the decision makers that were interviewed. We illustrate how the new similarity measure can be used to gain a better understanding of the structural resemblances and differences among the cognitive maps of the decision makers.