Later that year, we adopted the camera phone. Soon after began the rise and rise of the unsolicited texted dick pic – teens and grown men, sending photographs of their penises without warning or invitation to women and girls they barely knew. Anyone, anywhere, any time. In other words, technology enabled them to behave like four-year-olds.

This odd response to new technology did not prove to a short-lived lark. Instead, no matter how many times they'd been told by women to put it away and bugger off, the invasion of the uninvited penis pic has swollen into a phenomenon. I have daughters who, out of the blue, received them on their phones in high school. "Ew!"

This made me think it was a young man's game – but I have a couple of acquaintances in their 50s, men who seem at least halfway sensitive and respectful in their dealings with women, who carry on in this way. One of them is a veteran of online dating; he sends a pic of his enormity in the early stages of conversation, as a kind of "I'll show you mine, now you show me yours" kind of thing. It's an unspoken transaction he says, delicately traversed, even coded, no outraged response as yet. "We know what we're there for."

As with most human behaviours, it's not the case that one size fits all. Social scientists say there is little hard research into the dick pic, but they're being called upon to think about it. Is it simply the case than some men have never grown up? Is it a pants-down return to caveman courting, where the "boing" of a willy is being used as a club? Has modern life got so busy that men don't have time for conversation?

Psychology Today has run at least two articles that seek to explain the motivation of dick pic enthusiasts, the latest, posted in February, by Dr. David Ley, a clinical psychologist in practice in Albuquerque, New Mexico, and author of The Myth of Sex Addiction and Wives Who Stray.

In summary, Dr Ley – who notes that, without research data, he can but "speculate, though with some informed psychological wisdom."

In summary, Dr Ley suggests that dick pic represents an aspect of men's mis-perception of female sexual interest. "Men love the idea of receiving such pictures from strangers, and they assume women do too ... men really are hoping and thinking that you'll be turned on and send them a pic in response."

He says that male mating strategies have always included an element of "boldness," where "shock value" is a way to get attention. "And negative attention is better than no attention at all."

He also says it's probable that at least some of these men receive "a sexual thrill at the idea of an unknown woman seeing their genitalia ... and some of these men probably masturbate as a part of the act, imagining that woman seeing the picture they sent. The fact that a woman rejects them for it is not salient, because for many such men, it is the woman's disgust and rejection which is actually part of the turn-on."

He cites the case of the Naked Photographer, a man from Ohio who would jump out and expose himself to women, and take a photo of their reaction. "When he was caught, he later admitted that he would masturbate to the pictures of the women's reactions."

Ley notes that because men fear sexual rejection, by sending pics of their genitalia, "they are almost getting pre-approval. This way, they get the chance of rejection out of the way early, so they don't have to worry about being rejected or shamed once they drop their pants on a real date."

Ley's article in entirety can be found here.

Doctor Peter Jonason is a social and personality psychologist who conducts sex and relationship research using an evolutionary framework at the University of Western Sydney.

He sees the dick pic as a consequence of the "checklist mentality" that thrives in the online dating scene. "Online dating has shifted the game to being more image driven and more checklist driven. I think guys wrongly believe that women have 'big penis' on their checklist."

But why get to it so quickly? "Firstly, men are deluded in thinking women are selecting them for their penises. Secondly, the male mating strategy is a quantity approach. He'll send out 50 of those pictures: if only one woman says yes, he gets what he wants. With the dick pic he's saying, 'I'm here to have sex, and this is what I have to bring to the table.' It's a very a very male mating strategy, but they're going about it the wrong way. Too much too soon."

Dr Nicholas Hookway is a cultural sociologist at the University of Tasmania. He sees the dick pic is part of a "speeding up or acceleration of intimacy, driven by new communication technologies, but also reflective of a fast-paced culture that is re-writing norms of courtship as slow and gradual."

One consequence is the commodification of sex, "where humans are consumed as objects rather than related to." As sex becomes detached from love and commitment, contemporary eroticism is about the commitment-avoiding consumption of sensation and pleasure. "Love now dwells in an 'aesthetic' space whose key occupants are the sensual and the fast."

Hookway argues that the quick escalation to sexual display is "arguably reflective of how the skills of sociality are being eroded. A world where we spend more time interacting with mediated sexualised images than we do engaging in human face-to-face contact."

In short: the exchange of images – and the attendant appraisal of looks – has to an extent replaced conversation and getting to know one another, at least in the digitised environment.

Madeleine Holden is a New Zealand writer and lawyer based in London. In 2013, she set up a blog called Critique My Dick Pic. For $10, she appraises the aesthetic quality of the photograph – lighting, composition – but not the quality of the penis. Every day she receives too many photographs, such that she filters out the obviously gross displays. In an email conversation, I asked Ms Holden if she got a feeling that for too many men their identity and sense of self was too tied up with their cocks?

"Yes. I receive emails from men who are cripplingly insecure about their penises and when I look at their pictures, they are perfectly normal. Men seem to have a preoccupation with size that is disproportionate to women's preferences – that is, they seem to care way more than we do."

Maybe that's what it comes down to. Like little boys, such men are asking, "Isn't this great? Isn't it?"