DS is 15 months and he often picks something up and bashes his head with it, or bangs his head on a wall or a door. He seems to find it really amusing.
At first I just let him do it because I assumed if he realised it hurt he might stop doing it. Doesn't seem to be working like that though and he often has little bruises on his head.
What can I do? Will he grow out of it? Is this normal behaviour?