My son is 20 months old, and I am a stay-at-home mom. I also watch after the daughter (age 11 months) of my friend and a niece (age one month). My son has recently started hitting the 11-month-old, whom he had a very close relationship with until recently. No matter how many times I say no, or give him a time out, or even ignore him and soothe the child who is hurt and (I try to ignore his negative behavior and always try to praise his positive behavior), nothing seems to work. He doesn't seem to understand that he is hurting his friend. What worries me is that this is not an occasional hit, he hits her all day ... he will walk by and slam the poor child in the head, face, or hands (she is in a play pen). Should I worry? What should I do to stop this behavior? Should I talk to the 11-month-old child's parent about this (I know I would want to know)? Should I consider not watching her anymore? Please help, I am at my wits end!
Your predicament isn't uncommon. Twenty-month-old children are in the throes of the "terrible twos," a time of pretty intense frustration, which usually is acted out physically.
Take a step back to think about what motivates this behavior. He is probably feeling some negative emotion—envy, boredom, frustration—and doesn't yet have enough language to express these feelings (Don't worry; these skills are coming soon!), so he "acts it out." What you are seeing isn't an intent to harm, and keep in mind that your son doesn't yet have the ability to think about what other children may be feeling. Toddlers also have poor impulse control: once an idea takes hold, they can't check it easily.
So, your responses are the right ones. Don't reinforce his actions with much attention—even the negative attention of a scolding can reinforce toddler behavior (especially if it's your attention he's after). Spending time soothing the younger child creates a double negative for your son, as far as attention goes. Anticipate that his language skills will improve in the next few months, and encourage him to use his words by teaching him how to say what you think he may be feeling. Knowing he can't always stop impulses, you do need to be on the watch for potentially physical situations. I realize having three children to watch makes this hard, and that no one can be vigilant enough to head everything off at the pass. Finally, consistency is very important when dealing with toddler behavior no matter who is watching him. After most children turn 2 and their verbal skills improve, this type of physical aggression often gets better.
As to whether or not you should discuss this with your friend, I agree with you. I'd want to know what was happening to my child as well. But you can also emphasize that he isn't out to hurt her child, that you are there addressing the problem, and that his behavior will most likely improve in the near future.