Having been bred to be sentinel or watch dogs, Lhasa Apsos tend to be alert and have a keen sense of hearing. They are bright and outgoing, but some tend toward wariness of strangers. Wariness does not mean unwarranted aggressiveness but having a discerning attitude towards strangers; people approaching the dog simply need to show that they are a friend. However, many Lhasa Apsos are quite friendly from the first introduction. If not properly socialized, some may become aggressive or overly shy toward strangers.