I'm a science blog junkie.

your question. Could you elaborate?

I think what may be the question is this. The research that paper is talking about points to the dopamine surge as learned conditioning. So if you are conditioned to have an O at certain times or doing certain activity you would get the huge dopamine spike before the actual O.

I am sure there is something to this from the way things went for me early on. As well as my latest viewing of stimulating images.
I wrote end of last year how good looking at those images felt. I think just starting to look and looking at those images at the time set off the large dopamine spike. That is why it "felt" so good. It was the anticipation of what was coming. I had conditioned myself to expect the O when those images started to appear. I am sure there was another spike with the O though. No way there could not be.

Now my recent view of images I did not feel the same. I suppose nearly 6 months without reinforcing the conditioning was enough to break its link. So not the huge spike of anticipation dopamine or conditioning dopamine what ever you want to call it. I only got the surge with the O. The whole experience was not that rewarding not like my past conditioning. So it has been easier to deal with the reaction to those images since.

Also I suppose it explains some of the depression. It was hard for me at first with getting home after work or getting in the shower. I was conditioned to those times. Very conditioned. That is why I had crashes at those times. I even had my first big crash when taking a shower. My conditioning had me expecting the reward and nothing so it kind of crashed with low dopamine which caused just that mental break that it does.

I think it just says the same thing we already know. What we have all experienced.

There is one thing to add though. With this addiction I am betting there is that surge of expectation dopamine. Well I know there is I have experienced it. I also am sure that with O you get another large spike of dopamine. So I think the research is lacking there. What they show is a surge at the conditioned response point and then no surge with the reward. Well I think O's work a little different than fruit juice.

I would almost bet that there is more of a continuous increase of dopamine while looking at porn. You get a spike at the beginning. You get elevated levels while looking at images and M'ing to them. Probably even just M'ing does it to I am sure of it. But you add the images and the M'ing and the way this research talks about expectations. You get high dopamine for an extended period of time. Then you get that huge spike at the end with O. So the brain is getting very very conditioned with the P/M/O/F conditioning.

I think the article explains how I felt when looking at images.
I do remember that surge as I got home and turned on the computer. That surge in my body that said here we go. It was ready. Then when that first image appeared another spike. Then it was just one small spike after another as each new image appeared. Then keeping everything going with M'ing. Just one big dopamine ride till the huge finish. Easy to see how this is addicting. Cause I believe this process is taking that research to the extreme. I think they would be surprised by the scans of people addicted to porn and M and O and what it would show.

Maybe some of what I said made sense.

But the study is from 1997 hopefully there is others out there to back it up.

Kinda confirms my own insights in to rewards which tallys with things to do with hypnosis which I've heard about. For example, someone could be hypnotised to imagine they've just scored the winning goal in the world cup final! And they then carry it out and look like a bit of an idiot for over-celebrating something that never actually happened and everyone has a laugh, but afterwards they say that they felt a big surge of elation and so forth as if they'd actually done it! And it's all linked in to the fact that we are ultimately in control of how we feel, it just depends on how we choose to interpret our imagine of the world around us and what we are experiencing at the time.