Extensive simulation of sensory perception for NPCs (Non Playing Characters) or bots in 3D games has been quite rare if not absent until recently. However, a few games have proven that proper simulation of senses can lead to interesting and novel gameplay, and it is likely that the trend towards more sophisticated simulation will continue. In this paper we analyze the existing techniques to simulate virtual senses, highlight their weaknesses and propose some ideas to improve over the main existing approaches. The work presented here is part of an ongoing research on 3D learning characters, funded by the RMIT Emerging Researchers Grant. Keywords 3D Characters, Sensory Perception, Scene Graph.