My 1 1/2 year old won't stop humping?

I know it's "normal" for them to be curious, but please don't take offense, but sounds like your daughter has taken this to more of an "obsession" than just curiosity. Have you asked the doctor at any of your daughter's well child appointments? (Like we have a 12 & 15 month well child) I have a 14 month old son and he does "grab" and "touch" himself during the bath and naked time, but isn't solely focused on that. I know there are some behavioral/mental problems where kids get "obsessed or focused" on one activity, just because it's masturbating vs a toy obsession doesn't matter. For instance, if all your daughter wanted to do was play with ONE dolly constantly and couldn't be enticed to play with anything else ever for a long period of time, that would be just as concerning. I would def talk to the doctor about it. Does she go to daycare at all? How are her other developments? Talking? Walking? Does she respond to her name? Is she really not distracted by anything else? So if you get down on the floor and try to engage her with an activity, does she ignore you and continue to do it? How do you respond/act when she does this? If your very upset, maybe it's an attention thing. Like I said, without a doubt address it with your pediatrician