THE PHOTOGRAPH that usually accompanies this column is arguably the worst example of a byline picture in today’s newspaper market. When I sat for the photo my intention was to present a very particular face to the world: clever, wryly amusing and sexually virile with a look that says, in the words of Alan Partridge, “I’m in charge of my car.”

The result was very different. It has been variously described as looking like one of the Chilean miners before they got out and Betty Stöve, the Dutch tennis player and runner-up of the 1977 Wimbledon ladies final.

This used to be a problem confined to vain journalists. But social media requires all of us to think more carefully about how we present ourselves in public.

Scour Twitter, Linkedin and Facebook and you’ll find a sea of slightly worn-out looking men in open-necked shirts staring out at you with expressions ranging from stolidly determined through to mildly constipated.

This tiny piece of digital real estate has become a key design battleground and has to do far more than merely identify us: it has to stand for something. This was the point of research carried out by Nina Jones, a 17-year-old student who entered So You Want To Be A Scientist, a competition for budding boffins on BBC Radio 4.

As part of her research, she asked 3,500 students on Facebook to explain their choice of visual avatars, to see if any trends could be identified. It was a great idea, which uncovered a couple of nuggets.

“My profile photo is meant to give the impression that I possess a higher degree of gravitas and sophistication than I actually do,” said one respondent. Another admitted, “I used to have my wedding photo, but separated and now it’s one of me at the local getting sloshed.”

Jones, and her research mentor Bernie Hogan of Oxford University, hypothesised that “younger people are more self-focused, while older individuals focus on their network (through pictures of children, culture and pets)”.

All of this lands us squarely in the field of personal branding, which if the publishing industry is any guide, appears to have evolved into one of our most common obsessions: more than 100 personal branding books have been published so far this year.

These generally make the point that the quality of the product is more important than the logo, but psychiatrists are worried that the increased interest in “the brand of me” is less than healthy, encouraging narcissistic behaviour and generally rewarding the show-offs. What does it say about us that we are so interested in the presentation of ourselves?

“Think of yourself as a can of Coke, or a luxury bag,” wrote someone called Marianne Abib-Pech in another newspaper recently. “Work on your personal brand. Because if you are not in control of it, who is?”

This is a more contentious statement than I suspect even Ms Abib-Pech realises.

The working assumption among the personal-branding gurus is that we can control how others perceive us by presenting ourselves well. If a consistent look and feel is applied to everything we release in to the public domain, we can create value for ourselves in the jobs marketplace.

But this ignores the issue of projectability, which is central to understanding what brands are. In his excellent book I'm With The Brand, Rob Walker of the New York Timesillustrates this point in a chapter on the rise of Hello Kitty, one of the strangest and most revealing case studies in any area of marketing. Hello Kitty was created in the 1970s by the Japanese firm Sanro and is now a multi-billion-dollar industry.

The Hello Kitty’s image is attached to myriad product lines from toys and clothing through to bikes, mobile phones and a credit card. But what is it?

The design is purposefully bland – a cat with a bow on its head with few other physical features and no mouth. Unlike other merchandise success stories, it hasn’t had a successful film and TV career and has not been subject to a carefully created narrative.

It’s a blank canvas on to which young women around the world choose to project their hopes, aspirations and prejudices. Put another way, the brand is determined by the user, not the organisation who created it.