Abstract: Understanding how users perceive 3D geometric objects can provide a basis for creating more effective tools for visualization in applications such as CAD or medical imaging. This article 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. We use a cognitive experimental paradigm to evaluate the effectiveness of two types of orientation indicators on a person's ability to compare views of objects presented in different orientations. The orientation indicators implemented were colocated, which shared a center-point with the 3D object, or noncolocated with (displaced from) the 3D object. The study accounts for additional factors including object complexity, axis of rotation, and users' individual differences in spatial abilities. Our results show that an orientation indicator helps users in comparing multiple views, and that the effect is influenced by the type of aid, a person's spatial ability, and the difficulty of the task. In addition to establishing an effect of an orientation indicator, this article helps demonstrate the application of a particular experimental paradigm and analysis, as well as the importance of considering individual differences when designing interface aids.