I was reminded the other day about young children and Halloween. Many do not like the costumes. Why? Because for young children the line between fantasy and reality is not a clear line.
For young children, seeing IS believing, so you can start to think about what goes on in the child's mind on Halloween with all it's costumes.
Maybe it goes like this: "If I put on a mouse costume then I AM a mouse and then I'm not John anymore and that's scary."
Children get upset when parents put on eyeglasses or change hair styles. "Maybe you are NOT my parent – but some other person."
Halloween is not a fun thing until you are old enough to know about object constancy….until then, changing visions may mean the object has really changed.
So if your young child does not want to wear a costume – there is a good cognitive reason.