That is one of the things I don't like about Doctor Who(don't get me wrong I love the series). In the first episode the new companion is surprised, everything is new and somehow frightening. Like every human been should behave after discovering that. Two episodes later and the companion almost beats the Doctor to touch and interact with the strange things without any regard for they own safety. Like the Doctor himself said once: "There's a hole dimension here but space for only one mad man in a box"