So, according to Rep. Burgess, fetuses feel pain, and male fetuses masturbate as early as 15 weeks, and this is evidence that abortion should be banned much earlier than the 20 week ban under consideration. He further notes that, "There is no question in my mind that a baby at 20-weeks after conception can feel pain." Unfortunately despite his experience delivering babies, Rep. Burgess's views are well outside the mainstream scientific consensus and have no basis in reality. According to this systematic review published in the Journal of the American Medical Association, fetuses lack the ability to feel pain until the beginning of the third trimester, which is about 24 weeks, and significantly later than the 15 weeks suggested by Rep. Burgess.
So, what is going on here. I think we have a combination of Wishful Thinking and Pareidolia. Burgess has faith in the truth of his conclusions, so he goes out and looks for evidence that he thinks confirms his beliefs. When he sees sonograms of male fetuses with their hands between their legs, he interprets this as the fetus masturbating (why his mind goes there and why he doesn't think female fetuses masturbate is a question for the psychiatrists to answer). He sees the vague and random movements of an early term fetus and interprets those movements as purposeful because he wants that to be true because it supports his conclusions. The key here is that his beliefs about fetal pain perception are not formed on the basis of evidence, but rather he has decided that early term fetuses do feel pain, and then looks for evidence to support that belief. Someone who had a genuine interest in crafting effective legislation would develop positions on the basis of evidence rather than look for evidence that supports one's pre-existing biases.
h/t to Salon