Archive for September, 2009

The point of personas

Wednesday, September 23rd, 2009

I was at the Accessibility 2.0 conference in London yesterday and heard a couple of comments about personas that indicated they are still not very well understood. Since I have been teaching developers about them for around 10 years, I thought it might be helpful to provide some clarification.

The first thing to realize about personas is that they are primarily roles that users take while interacting with a system. But, instead of referring to users collectively (or to their more abstract role), we create a persona as a tangible representation. This turns out to be a good thing from a psychological perspective since research shows people are more likely to feel positive about an individual than they are a group with similar characteristics. So personas do really help to promote something I call empathetic design (see my paper for the CHI conference on why this is needed).

It important to emphasize that personas must be tangible. (This was one of the inappropriate references I came across.) You cannot on the one hand refer to Bob as a nuclear physicist who enjoys golf but then say he is aged 40 to 49. Bob needs to be a specific age, have a finite number of children and so on. Otherwise he is straddling the boggy ground between persona and user profile.

Returning to the roles issue, does it make sense to have a persona with a disability? While it would help as a reminder that the system being developed needs to be accessible, being disabled is not usually a role – it is an attribute. (The exception would be a system that was designed specifically for a particular disability, like the Nokia Braille Reader.) This does not diminish the importance of accessibility but does highlight the need to consider other contexts of use as a separate dimension. So while personas would provide focus for the tasks performed by defined user communities, the contexts of use would cover issues like user experience, frequency of use, range of abilities and so on. Of course, accessibility should not really be a separate consideration. With few exceptions, all systems should be designed to support users’ preferred or required interaction styles. This is something that most developers knew about when developing for the desktop but seems to have been forgotten in the intermittent gold rush that is Web 2.0.

(I cover Ajax accessibility in my course for NNG in Las Vegas and Berlin.)

Random acts of confusion

Saturday, September 12th, 2009

The magician Derren Brown recently ‘predicted’ the outcome of the UK national lottery, precipitating a kind of science versus society war in my household. While I have seen some clips from the two programmes, I refuse to watch the whole thing on the grounds that it is damaging to the public perception of science and mathematics.

When I see a card trick or a woman being sawn in half, I *know* it’s a trick. No cards or women are actually be harmed in the cause of entertainment (well, I am pretty sure about the women, but the cards might suffer in some cases). The problem with the lottery ‘prediction’ is that most people do not understand the fundamental nature of randomness. Brown’s pseudo-scientific explanation (using the wisdom of crowds) actually makes sense to them. (If you are unfamiliar with the theory, it is where the average of a large number of guesses is more accurate than the vast majority of individual guesses.) The problem is, and this is what makes the trick so effective – but confusing at the same time – it is not possible to predict with any degree of certainty what the next random number might be. In a truly random system, the history of the numbers drawn is entirely irrelevant. The only useful information that can be gleaned this way is whether there are non-random factors at play. So knowing the sequence of results from a roulette wheel might tell you it is not perfectly balanced and therefore slightly prone to choosing some numbers over others. But for a perfectly random system (and lottery equipment is as close as you can get to perfectly random), no amount of contemplation is going to make any difference.

Because of my scepticism, I am now forbidden from discussing the trick any further within earshot of my family (I don’t think they read my blog so I am not worried on that front). And I have to hand it to Darren Brown, its a good trick – even if the ‘predicition’ came shortly AFTER the actual draw. But please, can we have a trick next time that is not going to damage our already impaired understanding of science?