Having actors look at things in their environment, greatly improves believability. Perhaps a system to do this could be as simple as to trigger a “look at object” action every time an object enters a given radius around the actor (or semi-circle in front of the actor). This would happen both when objects approach the actor as when the actor moves through the environment.
If this starts looking too nervous, or if there are too many objects, perhaps the actor can choose to look at objects that he likes only. Or at objects that he encounters for the very first time (curiousity). And he should probably differentiate between inanimate items and other characters. Objects that approach him will probably also provoke more response than object he approaches (startled).