It
doesn't work particularly well. It doesn't reliably
promote the internalization of moral lessons, can degrade the
parent-child relationship,
becomes less effective the more often it's used, can promote antisocial behavior if it's delivered aggressively, and doesn't make the kid behave properly when the parent isn't around. The APA has
recommended against it, on the basis of the research I cited. It can create immediate compliance in the discrete situation where corporal punishment is applied, but it's usually at best ineffective and useless - not harmful usually, but also not typically an effective tool in teaching your kid how to behave. So why bother?
That Gershoff paper (
here) is a really good overview that analyzes the results of a number of other papers, so I'll refrain from citing more.
So why is it useless? According to Holden (2002), paraphrasing the work of Domjan's The essentials of conditioning and learning (2nd ed. 2002),
So I won't flatly assert that it doesn't work, and I didn't. The best available research doesn't convince me that corporal punishment is particularly effective in any but a vanishing minority of cases where parents are able to meet all of the above criteria consistently and without fail. Since it's usually the case that corporal punishment is pretty ineffective, and since doing ineffective things is kind of ridiculous, I stand by my earlier statement in its entirety.
Of course, it goes without saying that when a psychopathic person is punished, by whatever means, it's usually completely ineffective because they're deficient in the empathy required to feel shame or contrition and are therefore not inclined to internalize those emotions to change future actions. All they're gonna do is figure out how to not get caught next time.