In previous work, researchers have repeatedly demonstrated that robots' use of deictic gestures enables effective and natural human-robot interaction. However, new technologies such as augmented reality head mounted displays enable environments in which mixed-reality becomes possible, and in such environments, physical gestures become but one category among many different types of mixed reality deictic gestures. In this paper, we present the first experimental exploration of the effectiveness of mixed reality deictic gestures beyond physical gestures. Specifically, we investigate human perception of videos simulating the display of allocentric gestures, in which robots circle their targets in users' fields of view. Our results suggest that this is an effective communication strategy, both in terms of objective accuracy and subjective perception, especially when paired with complex natural language references.