A: Dear Amberthompson41:
You have raised a good question that seems to concern many parents. Professional people who work with children have found that hitting children has negative effects--naturally, the child is likely to stop whatever the child is doing at the moment but the overall impact is to make the child more aggressive, angry, and mistrustful of the parent who hits.
It is natural for 5 month old babies to want to pull at anything within reach. Their brains are wired for them to do so. It is also very likely that normal moods of excitement, love, or anger are also stimulated in a small baby by a thousand things that happen in the ordinary day--and your daughter may certainly give you the impression that she is getting enjoyment out of these personal attacks. Your intuition that she somehow knows that she is provoking you may be part of your suspicion that you need to do something about it.
It is not too soon to control the situation, so that you minimize the opportunity to pull hair and yank off eyeglasses. If you can, you might tie back your hair and lay your glasses aside for a few weeks when you play with your daughter, so that these things do not tempt her. When any baby or child does something that hurts another person, the grown-ups must step in right away so that the activity doesn't continue. You need to keep yourself, your hair, and your glasses safe! At the same time, you can certainly explain, "No no! We don't pull hair!" or something similar if you wish. The expression on your face will surely deliver the right message either way, since obviously you do not like it.
This is all you need to do: first, maintain safety by intervening quickly and actively, so that no one is hurt; second, provide a very brief explanation. Since your daughter is too little to understand language fully at this point, of course, the words are not really necessary. However, the principle of safety first plus explanation is all you need to do.
This phase will pass on its own. Distracting her and avoiding a hullabaloo will help.
Elizabeth Berger MD