A quick opinion about personas, prompted by a question from a friend.
When choosing a picture for a persona, use a real photo, not a cartoon. A cartoon doesn’t add life to a persona; it drains life from it.
It’s easy to think that the deliverable itself is the persona. It’s not. Your deliverable should create a shared mental model among your team; that is the persona. Mention a persona by name and you don’t want people to remember the paper stuck on the wall. You want them to remember a lifelike person. Only then can the entire team have a stable, realistic reference point for design discussion.
A cartoon doesn’t create this realistic mental picture. Viewers have to fill the gaps between the drawing and the reality, and tend to fill it with something close at hand – an extension of themselves (see Understanding Comics), or a crude stereotype. Therefore a cartoony persona often creates a rubbery, clichéd representation of a person, easily bent into whatever shape is needed to use as false evidence.
(Most people already have this mental model of users anyway, so your efforts will have been wasted.)
That’s not to say cartoons are useless. I use them often in high-level sketches to represent users we don’t yet know enough about. I’ve also used them to extend an existing persona, particularly when illustrating how a specific persona uses a product through a storyboard.
The storyboard isn’t photorealistic, so it follows that the protagonist should be hand-drawn also. But I only use this shorthand once the team has grown to know and love a photorealistic persona; that is, once the mental model has been established.