Last summer I was invited by the lovely people at the Latitude Festival to participate in a debate at the Literature Tent on the impact of online pornography on society.

It was chaired by Dr Suzi Gage (@soozaphone) of Bristol (and by now Liverpool) University, known for her popular Guardian science column and podcast Say Why to Drugs. The other panelists were Martin Daubney (@MartinDaubney), former editor of lad’s mag Loaded for eight years and theatre-maker Christopher Green (@Kit_Green) creator and player of comedy Country ‘n’ Western heroine Tina C.

My role was to bring the neuroscience perspective, Martin the media perspective and Chris was taking the arts angle. I got prepared quite a few weeks in advance and was stunned by what I found lurking in the academic literature. So I thought I’d share my main findings with you here in this month’s blog.

When people think of addictions, compulsive consumption of various psychoactive substance is usually the first thing to spring to mind. Much research has demonstrated a hyper-responsiveness of the reward pathway – the ventral tegmental area in the midbrain and nucleus accumbens in the ventral striatum in particular – to drug-related images in the brains of people addicted to recreational drugs like, for example, cocaine. This body of research also demonstrates that the activity generated in the reward pathways of drug addicts to pleasant images of scenes unrelated to drugs, is somewhat diminished compared to non-drug takers. In other words, excessive consumption of drugs seems to subtly rewire the reward pathway so that it becomes more sensitive to visual scenes relating to their preferred recreational drug and less so (than normal) to everything else. It seems this is not just limited to drugs, a similar impact on brain function is seen in people who over-consume porn too.

It is important to bear in mind that the reward pathway is not only important for generating feelings of happiness when we participate in pleasurable activities, but it’s also instrumental in predicting what choices might bring us rewards in the future, which means it is critically involved in decision making. It’s role in helping us evaluate the benefits of one option over another extends to the point where this system, in combination with other nearby brain areas, can be thought of as providing the very drive that motivates us to pursue one course of action over another.

In recent times, research into excessive consumption of various products accessed through the internet – online gaming, gambling and pornography, to name but a few – also leads to behaviours that have all the hallmarks of addiction, not to mention the altered neurological responses outlined above. There has been some resistance to this idea in various academic communities, but the movement to have these “arousal” addictions included in handbooks of psychiatric illness symptom classification, and in particular the DSM-5, is starting to gather momentum.

On the basis of a huge survey investigating the pornographic consumption and sexual experiences of 28,000 Italian teenagers it seems that, for about one in ten boys who consume explicit online pornography on a daily basis, the habit is interfering with their ability to engage in real life sexual activities:

It starts with lower reactions to porn sites. Then there is a general drop in libido, and in the end it becomes impossible to get an erection

Carlos Forsta, President of the Italian Society for Andrology and Sexual Medicine.

This may at first glance seem to fly directly in the face of the stereotype of the ultra-horny teenage boy, brimming full of the very sex hormones that would usually ensure a hair-trigger sexual response to any possibility of coitus. But in light of research conducted many years ago by joint winner of the 1973 Nobel Prize for Physiology or Medicine, Nikolaas Tinbergen, it starts to make a lot more sense. In experiments conducted with “supernormal” stimuli, he observed that birds preferred to sit on larger than normal and / or more colourful eggs constructed from plaster, rather than their own real eggs. Similarly, herring gull chicks would peck harder and more often at a fake adult herring gull beak with brighter or more numerous red spots than the real thing, in a vain effort to elicit a regurgitated dinner. The point is that the larger than real life stimuli seem to have short-circuited the birds’ primal instincts leading to a preference that would ultimately be deleterious to the survival of the bird’s progeny.

It seems that the ubiquitous availability of explicit internet pornography is leading to a similar scenario in modern day internet addicted teenage boys. A subconscious preference for artificial, supernormal, explicit porn over actual sexual partners seems to be occurring with alarming regularity in adolescents who let their penchant for titillating pornographic films get out of control. In his TED talk entitled “Why I stopped watching porn” Ran Gavrieli gives an excellent and compelling account of some of the key differences between what pornographic films actually show and the relatively tame sensory stimuli involved in genuinely satisfying, intimate sexual behaviour between consenting adults.

Essentially, he points out that themes typically conveyed on free online porn sites, such as female subordination and extreme close ups of penetration to name but a few, are the human sexual equivalent of the brightly coloured, super-sized eggs and beak markings from Prof Tinbergen’s experiments (just not in so many words!). Porn is a supernormal stimulus, dominated by explicit close ups of penetration that you simply can’t reproduce in reality (the penis and eyeballs will always be separated by a set distance, unless you are exceedingly flexible, of course). Inevitably the real thing pales into insignificance by comparison after sufficient daily use of explicit porn of virtually infinite variety. No wonder boys are struggling to get it up!

This isn’t to say that there is no place for pornography in society. Regardless of your attitudes on this topic, it certainly isn’t going away any time soon. However it may be useful for porn fans to bear in mind the concept of everything in moderation. Once one genre of porn is no longer arousing there are many other categories to choose from. Once the relatively soft porn is no longer stimulating, casual browsing will always yield more explicit options. Eventually the kind of sexual activities we are likely to have access to in real life become insufficient to yield an erection for long enough to reach climax, which will inevitably lead to relationship problems. And nobody wants that.

The good news is that abstinence from pornography is usually sufficient to enable normal biological sexual function to eventually return. Interestingly, in older men this takes two months, whilst in younger men it can take much longer: four to five months. Find out more in the Latitude Podcast of the Porn Perspective Debate.