Though I understand it's substantial reading, these have been the more articulate papers I've seen implicated in discussions around pornography and asserted associations.
A Sensible Antiporn Feminism - A.W. EatonAs summarized
My investigation will take the following shape. Section I provides an argument for APF and outlines some of its central tenets. Section II disentangles the various sorts of injury that pornography is thought to cause, exposing a wide array of harms that vary considerably in their character and severity. Section III examines the most common criticisms of APF and argues that they can be deflected by attributing to APF a more sensible conception of causation. Section IV assesses the current state of the evidence for APF’s case and outlines a path for future research. Section V addresses some lingering objections and suggest some problems for further reflection, while Section VI provides a brief conclusion.
They basically help bring clarity to the debate in hopes of progressing it.
Sexual Solipsism - Rae LangtonRae Langton made a bit of a splash on the philosophical debate of objectification here. The classic concern of objectification that despite the idea that people treating things as people (ie porn) being seemingly benign, it may not be so if it has implications for the reverse, treating people as things.
Objectification - Martha NussbaumAnother liberal philosopher well known for her work on objectification, M. Nussbaum, brings a broad conception of objectification and in it's breadth argues the difference between what would be morally benign or even virtuous forms of objectification and what are immoral or plausibly harmful.
To which I think it should be made clear from this work that feminists aren't concerned with the morally benign kind when they're criticizing porn should they use such a definition.
Rae Langton has also been quite interesting in using a liberal framework to take novel approaches in criticizing porn based on the premises in which it's currently defended in the US, ie free speech.
Projection & Objectification - Rae LangtonHere she explores the whether certain forms of objectification in themselves affirm a practice denying autonomy through affirmation of autonomy. This may sound odd but I'll provide snippets to help summarize the idea.
p. 296
Attribution of matching desire, through women's supposed capacity for vaginal orgasm - a science fiction about women that was long accepted as orthodox science. MacKinnon's explanation is that because 'men demand that women enjoy vaginal penetration', they acquire the belief, dressed up as science, that 'vaginal orgasms' are the only 'mature' sexuality; and accordingly the belief that women desire penetrative sex because this is their natural route to orgasm.33 Wishful thinking projects an imagined biological basis for a conveniently matching desire on the part of the woman, and adds whatever legitimisation is granted by a scientific establishment - an eery pseudo-science parallel to the science-fiction biology of Deep Throat. Does such an attribution of matching desire objectify women? One might suppose again that the attitude itself is not objectifying, that on the contrary it attributes an active independent desire to women, a distinct source of pleasure unique to women, that however erroneous, it is at least subjectivity-affirming and autonomy-affirming. This would be too hasty, given that the attitude denies that women have sexual experience they have, and asserts they have sexual experiences they lack- something that may count as subjectivity-denial, rather than affirmation. 34
There may also be instrumental thinking involved; how much more useful if the shape of women's sexual desire were the perfect match to that of men! The theorizing in turn perhaps helped to legitimate instrumental sexual use of women by other parties, by silencing, as 'immature' those women whose desires were apparently less convenient.
Also summarized in another paper discussing implocations of describing women's attire as provocative.
PROVOCATIVE DRESS AND SEXUAL RESPONSIBILITY - Jessica Wolfendale∗p. 41
Secondly, and perhaps more troublingly, the provocation model illustrates what Rae Langton describes as the denial of autonomy through the affirmation of autonomy.83 When a woman’s outfit is described as provocative, she is not only reduced to a depersonalized sexual object or collection of sexual body parts. In addition, a specific subjective desire is attributed to her⎯the desire for sexual attention from men. But this attribution is not a form of respect for her autonomy. Instead, it denies her autonomy by undermining the credibility and authority of her actual desires, even if she explicit and repeatedly denies the attributed desire. Her stated preferences, if inconsistent with the intentions and desires attributed to her by men, are dismissed as not reflecting what she ‘really wants’⎯she says ‘no’, but her outfit says ‘yes’. Thus, it is men’s interpretations of her desires and intentions that are take as authoritative. Women’s actual spoken desires and intentions regarding men’s sexual attention are therefore silenced.
The authority given to men’s projected desires above women’s stated preferences creates an additional layer of potential menace to women’s choices regarding their clothing and their actions. Knowing that, despite one’s intentions and clearly stated preferences regarding sexual attention from others, one could still be accused of ‘wanting it’ or ‘asking for it’ is both destabilizing and highly disempowering.
Which I think is particularly interesting considering the shift in advertising decades ago from the typical understand of objectification into whats been coined as sexual objectification, which is not as intuitively problematic.
Empowerment/Sexism: Figuring Female Sexual Agency
in Contemporary Advertising - Rosalind GillBeyond Belief: Pragmatics in Hate Speech and Pornography - Rae LangtonRae Langton still within a liberal framework also explores whether porn/objectification of a particular nature (ie that which could be identified being misogynistic) could contribute to a dehumanizing view of women and as such constitute hate speech, thus not worthy of being protected by free speech.
These works aren't empirical, but are an attempt to make clear certain ways of thinking identified as problematic by feminist thought. I think they take a softer position than radical feminists historically identified where the position isn't a blanket opposition to porn but to porn of a particular nature if proven it was significantly associated with certain effects upon people's psychology and eventually behavior.
I can't remember which one, but I also found interesting as a general point about the possible dangers in which the pleasurable feelings associated with pornography may make people irrational in identifying possibly problematic nature of things since they have such a positive association.
https://www.ethicalpolitics.org/ablunden/pdfs/For%20Ethical%20Politics.pdf#page90
-For Ethical Politics
: 
- By late