Mary said: 
“A late term fetus is more valuable [than an earlier-term fetus], and even pro-lifers acknowledge this in practice. For example, pro-lifers often focus on Tiller and late-term abortionists.”

My response:
I think this is a misunderstanding of our view, although I can’t speak for everyone. You know I’m all about intellectual honesty, so I’ll freely admit that late-term abortion photos hit an emotional nerve for some people that just aren’t reached with a 1st-trimester photo. Part of this might be a common ground point: many pro-choice people are against late-term abortions that aren’t about saving the life of the mother. Ideally some who haven’t thought of that particular facet of this debate will see the picture, perhaps be surprised/horrified that abortions on late-term fetuses even happen, and then the dialogue moves further, even if the person doesn’t become full-on pro-life-rights, or whatever you’d prefer my “side” to be called.

The sad part of this, and evidence that you may actually be partially right here, is that I heard a national pro-life group report that their fundraising letters that talked about fighting partial-birth abortions (technically known as D&X procedures) statistically brought in more money than other topics that would be chosen. One thing that could be interpreted from that is the pro-lifers receiving the fundraising letter have their heart-strings pulled more by late-term abortions than early abortions, thus they give more money to stop the late ones, and if that’s the case, while they may not be thinking about it this way, they ARE acting like late-term fetuses are more valuable than first-trimester fetuses. So I’d say you have a valid point, but I would point to different evidence to prove it. 

I think naturally whatever pictures are most effective will be used. I’m sure when Martin Luther King Jr. was picking out pictures of lynchings, he probably picked the gorier ones to instill a more emotional/gut response. 

Some would argue that it’s just a gut response, and doesn’t mean anything. I definitely don’t think the pictures should replace logical arguments, but there is something about our gut responses to abortion pics that shouldn’t be ignored. A wise man once said, “repugnance is the emotional expression of deep wisdom.” The same man, an atheist I believe, said, “shallow are the souls that have forgotten how to shudder.” [I'm quoting Leon Kass here in his essay on human cloning: "The Wisdom of Repugnance"] I think it’s worth asking why these pictures are so disturbing. I don’t think it’s because all surgery pictures are gross. In fact, some pro-lifers use that argument in defending the pictures, but I think the argument is crap. There is something very different about abortion pictures than other surgery pics… 

Naomi Wolf, one of the most celebrated feminists of the modern era and an ardent abortion supporter, questioned anyone who is willing to support abortion without also having the stomach to face its violent reality. She said it this way:

“How can we charge that it is vile and repulsive for pro-lifers to brandish vile and repulsive images if the images are real? To insist that the truth is in poor taste is the very height of hypocrisy. Besides, if these images are often the facts of the matter, and if we then claim that it is offensive for pro-choice women to be confronted by them, then we are making the judgment that women are too inherently weak to face a truth about which they have to make a grave decision. This view of women is unworthy of feminism.”