||Understanding how users perceive three-dimensional (3D) geometric models can provide a basis for creating more effective tools for visualization in applications such as CAD or 3D medical imaging. This dissertation examines how orientation indicators affect users' accuracy in perceiving the shape of a 3D object shown as multiple views. Multiple views force users to infer the orientation of an object and recognize corresponding features between distinct vantage points. These are difficult tasks, and not all users are able to carry them out accurately. A cognitive experimental paradigm is used to evaluate the effectiveness of four types of orientation indicators on a person's ability to compare views of objects presented in different orientations. The orientation indicators implemented were colocated, noncolocated, static, and dynamic. The study accounts for additional factors including task, object complexity, axis of rotation, and users' individual differences in spatial abilities. Results show that a colocated orientation indicator helps users the most in comparing multiple views, and that the effect is correlated with a person's spatial ability. Besides the main finding, this dissertation helps demonstrate the application of a particular experimental paradigm and analysis as well as the importance of considering individual differences when designing interface aids.