The content of what [patients] found exciting changed as the Web sites introduced themes and scripts that altered their brains without their awareness. Because plasticity is competitive, the brain maps for new, exciting images increased at the expense of what had previously attracted them. (p.109)

Do a viewer's most recent porn tastes reveal his "deepest urges and most uninhibited thoughts," as Ogas and Gaddam claim?  Does his sexual orientation change along with what he views? Or does cyberporn manufacture superficial tastes, sometimes unrelated to sexual orientation? Most likely, the latter.

Porn has changed...a lot

Words, pictures, audio and video are nothing new. Why then are people complaining about being "addicted" to the Internet, email, Facebook, video-gaming, i-Phones, or Internet porn? Because today's superstimulating versions of these activities are, in fact, potentially addictive. Surfing the net, especially for porn, incorporates all the activities that spike dopamine and keep the reward circuit buzzing: seeking and searching, sexy material, anticipation as each page loads, novelty on demand, and surprising and shocking visuals.

Obviously, a once-a-month Playboy, or an 80"s VHS tape cannot compare to using two high-definition screens, with 6 windows open, to search until you find just the right shot to take you home. After a bit of a breather you can search via Google for something you've never seen, so you can whack away once more. Unlike static porn of the past, today's Internet porn is so stimulating that, in some brains, it can gradually produce addiction-related changes.

No wonder a guy's brain can grow numb and stop responding to conventional sexual cues. Once vanilla porn is no longer doing it for him, his sexual tastes may prove surprisingly fluid. When his current cyberporn genre doesn't arouse him, does he think, "Oh, that's a sign that my brain needs a time-out to return to normal sensitivity, so why don't I lay off the porn?"

No. He unthinkingly does something that none of his ancestors had the option of doing (but would have done too). Out with the old and in with the new—because novelty triggers the surge of dopamine he needs to become aroused. He clicks around the Web until he hits something that engorges his penis. A novel pornstar may be sufficient, but perhaps after his fourth session of the day, he needs an added jolt of shock or anxiety to goose his dopamine and light a fire under his brain's sluggish reward circuitry.

For some guys this innocent reflex can have one or both of the following undesired effects:

1.     Rewiring: The user inadvertently carves new arousal pathways into his limbic system. As researcher Jim Pfaus points out, "the mating brain is opportunistic." It's not strictly bound by intrinsic wiring, but rather it adapts to promising sexual cues. This is especially true during adolescence, when the brain is primed for wiring up sexual cues.

Thanks to evolution, fertilization is the brain's top priority, so—even if a porn user would prefer to forget what he just saw—his brain carefully wires up all associations that led to his orgasm. It wants him to be able to "fertilize" this target again in the future. With enthusiastic use, a new brain pathway can become a 'pathway of choice,' irrespective of fundamental inclinations. In short, nerve cells that fire together wire together—especially if they produce a 'bigger 'n' better' orgasm.

2.     Desensitization: "Two hours edging to porn? That's what Google is for." "Two ejaculations since dinner? Let me fire up my old laptop so I can watch more windows on an additional screen." Unlike other mammals, a guy can override his natural limits using ever-novel porn. 

Over time, a user's brain can physically change. Signs of fundamental brain alterations (as contrasted with short-lived habituation) may include: chronic weakened impulse control, craving spikes in response to cues he associates with porn use, and decreased sexual responsiveness. He's no longer registering pleasure normally; his desensitized brain is desperate for the dopamine hits from stimulation. To climax, he needs to watch for longer or move to new genres of porn.

Small wonder that, as users slide along the porn spectrum in search of the next big "O," they can end up climaxing to visuals that are unnerving—or even illegal.

Anthony: I started looking at porn, on a regular basis, about five years ago. First there were the beautiful women, then the hardcore porn, then the weird insertions, then the transvestites, then critters, then the hermaphrodites, then the teen porn, then the younger models and now prison (soon to go). As the years passed I became less and less interested in masturbating and more and more interested in "novelty" searching. Looking back, I just don't see how I failed to recognize that I had a problem.

Sexual orientation versus synthetic sexual tastes

Obviously, a user who climbs aboard the Internet porn train can end up getting off at stops that were once inconceivable. Perhaps the most bewildering is, "Help! My penis is only responding to erotica I associate with someone else's sexual orientation." 

Ryan: I seriously thought I was turning gay. My obsessive thoughts about this issue were so strong that I was contemplating taking a dive off the nearest high-rise. I felt so depressed. I knew I loved girls and I couldn't love another dude, but why did I have ED? Why did I now need transsexual/gay stuff to get off? It's like I made a mistake that I cannot correct anymore. I want to go back to my old days when I was only turned on by the female body.