You said “parents only”, but I’m going to give you some advice anyway. DO NOT give him little pats on the hand. If you are going to use physical punishment, you have to actually cause some pain, or it’s useless. What’s more, it leads to a cycle of behaviour that often ends in physical abuse.
Have you ever seen a parent being far too rough with a child? The other day, I was in the bakery, and there was a woman there with a small child. He kept touching things, asking if he could eat things, etc. The woman was getting mad, he wasn’t listening, she tried being firmer, and so on.
Long story short, he grabbed something he shouldn’t have, she angrily pulled him away, and damn-near dislocated his shoulder. Is she a terrible parent? Not quite…
If a rat is punished for an action with a strong electric shock, it extinguishes that behaviour almost instantly. If another rat is punished with a weak electric shock, nothing happens. You increase the strength of the shock, nothing happens. You increase the strength again, nothing happens.
Pretty soon, you are giving the rat a much, much stronger shock than the rat who got the strong shock to begin with, but the behaviour that is being punished just won’t stop. It can get to the point where the rat is actually suffering physical harm, but it won’t stop doing whatever it was doing. This has been shown in other mammals as well, and the conclusion is pretty clear: punishment works, but only if you do it right.
If you make a mistake, and there are many mistakes you could make (eg., providing a discriminant stimulus: “I only get punished if daddy is home”), it will not work.
I’m not suggesting you beat your child in any way. In fact, I would suggest you stay away from positive punishment (eg, hitting, yelling, etc) as much as possible. At the same time, negative punishment (time-outs, “go to your room”, etc) are not likely to be effective with an 11 month old.
Use positive reinforcers as much as possible. You seem to be ignoring the child when it is good, and pubishing it when it is bad. Your attention is reinforcing, so it will keep being bad. What would happen if you ignored your child when it is bad, and gave it attention when it is being good?
Or better yet, if your child is being bad, why not give it something stimulating and rewarding to do instead? It works for children with autism, it will definately work for a child with no behavioural disorders.