Archive for the ‘User experience’ Category

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?

Why Metaphor is a Double-Edged Sword

Wednesday, August 26th, 2009

[Author’s note, 2009: This is the first article I wrote for the ACM’s interactions magazine, back in 2000. What is interesting, reading it again 9 years later, is that almost nothing has changed. The desktop metaphor is still in widespread use but remains largely broken. The shopping cart metaphor continues to be the best example of the effectiveness of metaphor, which is frankly more than a little disappointing!]

Don Norman is not one to steer clear of controversy. In The Invisible Computer he writes of his disapproval of metaphor in the design of user interfaces – an opinion that he has repeated in debate on the CHI-WEB email list.

What’s all the fuss about? The original issue in CHI-WEB was whether to use a shopping cart metaphor when designing e-commerce sites. Some contributors pointed with glee to examples of shopping sleds and wheelbarrows, while others insisted that a cart is a cart is a cart. Don said that we shouldn’t be using any of these things and should just have “lists of items purchased”. Naturally, this left quite an air of confusion over the whole subject. To try to iron things out, metaphorically speaking, we need to have a better understanding of some of the issues.

Metaphor attempts to express a new domain (the target) in terms of one that is already understood (the source). This is quite common in language where we discuss negotiation as if it were war (“he stood his ground”), use the term higher to mean more and view life as a journey (as in “where do you want to be in two years?”). Some psychologists even argue that thought and language are fundamentally metaphoric. Unfortunately this model of metaphor is very complex, requires a good understanding of both the source and target domains and is very specific within culture and language. An approach that suits user interface design better is called the structure mapping theory of analogy and is the work of Dedre Gentner and her colleagues. This theory still relates target and source domains, but by considering the relationships between the conceptual objects (concepts) within each.

The Controversy

What are the objections to metaphor in user interface design? The most commonly quoted are that metaphor is not helpful except to inexperienced users and that it is overly restrictive. The “desktop” metaphor, which is the basis of most graphical environments found today, is often cited as an example of the failure of metaphorical design. However, I think it deserves a closer look. Figure 1 shows a conceptual model of the source domain – an office of the mid 1970’s. The rectangles represent concepts while the connecting lines are relationships. I have drawn this in the style of a UML class model so that concepts and relationships are read from the labeled end of each line. So, for example, in-tray receives document and filing cabinet stores folder. This model (with some minor changes, such as printer instead of copier) was the basis of the desktop metaphor used on the Xerox Star, the inspiration for the Apple Macintosh, Microsoft Windows and other graphical environments. The trays, folders, documents and other concepts were represented with clear icons and descriptive text, allowing inexperienced computer users to rapidly learn the use of a complex and innovative computer system.

Notice, by the way, that Figure 1 includes a relationship that really isn’t of the same type as the others: desktop covered by blotter. While this relationship was certainly true of many desktops at the time, most of the other relationships are concerned with actions. The desktop relationship with blotter is superficial and not part of the system of relationships that interest us. This is called a non-systematic relationship.

Conceptual model of a desktop showing relationships between documents, folders, trays and similar

Conceptual model of a desktop showing relationships between documents, folders, trays and similar

Figure 1, Conceptual model of a mid-1970’s office

But why is the desktop metaphor unhelpful? I think the desktop metaphor on our computer screens has drifted too far from the original office domain. Microsoft Windows, for example, hides the in-tray and out-tray in an email application, variously called Mail, Inbox, Outlook or Outlook Express depending on the age and configuration of the system. The desktop is confusingly covered by wallpaper and printing documents by dragging them to a printer does not work reliably. The Macintosh does not fare much better and also has the odd feature of allowing users to drag the floppy disk to the wastebasket (“Trash”) in order to eject the floppy. From the office domain it’s obvious that the effect of that action (if any) should be the same as discarding a document or folder. So in most cases, the apparent problem with the desktop metaphor is that it does not correspond to the original office domain.

Now to the suggestion that metaphors confine their designers and users. This supposes that by establishing a well-understood system of relationships we are limited to just those relationships. Although it is likely that inexperienced users will understand the metaphor very literally, this same understanding will give them the confidence to explore and experiment. As long as we do not introduce anomalous relationships such as wastebasket ejects floppy, there will still be considerable freedom to innovate. For example, within the desktop metaphor, we could make use of a stapler to group and compress documents (as compared to the now common zipper concept which is not part of the office domain). We can also use bridging concepts to move from one metaphor to another. A screwdriver (Figure 2 ) could be used as a bridge from the desktop metaphor to the physical hardware. More advanced users might be able to drag the screwdriver to the filing cabinet to perform maintenance operations such as modifying partitions or defragmenting storage. All of these metaphorical design features could be in addition to more direct (but less predictable) mechanisms such as popup menus and shortcut keys.



Figure 2, Bridging concept from desktop to hardware

Some Problems

Having defended the general concept of metaphor, let’s be honest about its limitations. The first problem is that designers sometimes try to be too literal in their use of metaphor. For example, in a real office, mailing a document to a customer means that you no longer have a copy of it, unless you have explicitly made a copy beforehand. Enforcing this behavior in our virtual office would be incredibly frustrating to users. Mindless consistency is not an attractive design strategy.
A larger difficulty is that there really aren’t that many useful metaphors for completely new problem domains. The most successful metaphors are those which “virtualize” an existing problem domain. This means adopting not only the concepts and relationships of the domain, but also the activities, as shown for a “virtual store” in Figure 3 . Other candidates for virtualization are libraries, clubs, medical services, automotive sales and service – in short, most things that have well-defined domains.

Diagram showing relationship between shopping, checkout and delivery activities

Diagram showing relationship between shopping, checkout and delivery activities

Figure 3, Activity (state) diagram for a virtual store

The Name is the Thing

The debate over terms shopping sled versus shopping cart may seem relatively trivial at first sight. It is easy to forget that to inexperienced web shoppers, a shopping cart may be a familiar comfort. Arriving at an e-commerce site that does not use the shopping cart metaphor may be a learning experience, rather than a shopping one. It could also be a wasted learning experience if most other web sites use different concepts and activities. The novelty will be beneficial only if it offers a real improvement over familiar solutions and is adopted by the Internet community as a whole.

An Iceberg Model of Metaphor

Many concepts are domain specific. For example, a cash register is almost always associated with shopping and the activity of paying. Other concepts, such as money are much more general. The image of money in an e-commerce site may be associated with paying, but it may mean pricing, discounts or currency. The difference is that using a domain-specific concept such as a cash register invokes the system of hidden relationships to which it belongs. The cash register may be the only visible evidence of the metaphor, but the rest of the shopping domain is lurking beneath the surface.

This iceberg model of metaphor can present problems as well as providing solutions. A number of web sites have taken to using the term check in. Some use it as an activity required of visitors to the web site (i.e., registering or joining), while others ask existing members to check in. Which is right? The term check in is used almost exclusively in the travel industry to mean registration for a pre-arranged journey or stay and so is associated with a reservation as shown in Figure 4 . The question of whether the customer is a visitor or a member does not really arise, except that a member might be tenuously considered to have a reservation. It would be best not to use the term at all outside its travel context.

Image showing reservation as a concept hidden below the surface of check-in

Image showing 'reservation' as a concept hidden below the surface of 'check in'

Figure 4, Check in has a reservation hidden below the surface

Metaphoric Guidelines

My own view is that metaphor is an important tool for user interface design, but must be used with care. The guidelines below cover some of the most important issues:

Metaphors operate on systems of relationships, not on individual concepts. Make sure that the system of relationships is reflected in your user interface and do not use concepts out of context.

Metaphors do not have to be complete, but interfaces need to provide adequate clues to users. Omitting less important concepts or changing them slightly may not have a large impact on usability, but only testing will tell.

Metaphors should not rely on mere appearance. A concept should not just have the appearance of a shopping basket, it should behave like one too. It needs to have the same or similar relationships in the target domain as it did in the source.

Avoid non-systematic relationships (such as desktop covered by blotter in Figure 1). Most of the important relationships will be how concepts interact with each other, particularly from a user’s perspective.

Don’t let abstract relationships interfere with the metaphor. For instance, it may be true that a desk and a filing cabinet are both instances of office furniture. However, it’s their purpose that is of interest.

Choose metaphors that provide concrete images. The shopping domain is useful because it contains a number of domain-specific concepts that can easily be represented visually: shopping cart (or basket, trolley, etc.), cash register, price tags, discount signs, etc. A catalog metaphor, by comparison, is relatively devoid of distinct concrete images (an order form is not as immediately recognizable as a cart or basket).

Try to get as close to the original domain as possible (unless an alternative has obvious advantages). Mail-order shopping and vending machines are already one step removed from the source shopping domain. Also, some aspects of the vending machine domain are not entirely beneficial to e-commerce: Vending machines usually sell low value items, most require payment in advance, and not all are reliable.

Beware culture-specific metaphors and concepts. Cart (US) versus trolley (UK) is a minor issue since the image is the same. However, kiss and ride (dropping off a loved one at a purpose-built public transport facility) does not enjoy wide-spread recognition.

Further Reading

Gentner, Dedre and Markman, A. B. (1997), ‘Structure mapping in analogy and similarity’, in American Psychologist, Vol. 52, pp. 45-56.
Ortony, Andrew, ed. (1993), Metaphor and Thought, Cambridge University Press, Cambridge.

Copyright Notice

First appeared in interactions, Volume 7 , Issue 3 (2000), pages 11-15, Association for Computing, New York, NY.

Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee.

Dates study, user experience benchmarking and more…

Wednesday, July 8th, 2009

Many thanks to the hundreds of people who took part in our dates study. We had almost 1,000 responses in a one week period. I have written a full report of the study and put it in the resources section of our site – – but read on for a headline summary. Respondents who used month-first order were torn between ‘8/2/09’ and ‘August 2 2009’ with the former slightly ahead. Those who used day-first ordering had a strong preference for ‘2 August 2009’ while a very small number of respondents used the ISO date standard: 2009-08-02. Having said that, the thing I really wanted to know was whether people used leading zeroes without being asked. The answer is pretty much ‘no’. 76% of all responses used no leading zeroes in the day or month. Read the full report to find out why this is interesting (to me, at least).

Having spent 7 years benchmarking intranets, it is now the turn of e-commerce sites. The first in our new series of user experience benchmarking reports addresses the UK mobile phone market and covers 12 of the leading vendors: Argos, Carphone Warehouse, Expansys,, O2, Orange, phones4u, Tesco, T-Mobile, Three, Virgin Mobile and Vodafone. There were some big surprises in the ratings – see our overview at Also, join our UX benchmarking email list to have a chance to win a personal copy of the report. Just send an empty email to (unsubscribing is easy too).

Finally, a reminder of our upcoming courses. We are running our full-day card sorting and Ajax interaction design courses in London, Las Vegas and Berlin in the Autumn (the later two venues as part of the Nielsen-Norman Group conferences). See and for further details (and to book the London dates).

Card Sorting and Ajax Usability Courses in London, Las Vegas and Berlin

Wednesday, June 3rd, 2009

We have been asked by the Nielsen-Norman Group to present our card sorting and Ajax usability courses at their Usability Week conferences later in the year. (The half-day versions were well-received at CHI 2009 in Boston and will appear at HCI 2009 at Cambridge University in September – see

So here is the current Autumn schedule:


  • 5 October 2009, London
  • 11-16 October 2009 (part of NNG Usability Week), Las Vegas


  • 6 October 2009, London
  • 11-16 October 2009 (part of NNG Usability Week), Las Vegas
  • 15-20 November 2009 (part of NNG Usability Week), Berlin

The dates for the Nielsen-Norman Group presentations have not been fixed yet, but will appear on their site in due course ( I would be happy to answer any questions about the content of these courses, but all practical arrangements will be through NNG.

For the London courses, you can book directly through our web site. Discounts are available for groups of three bookings or more. A further discount is available (on the one-day price) for places on both days.

Visit: for Advances in Card Sorting (5 October, London) for Ajax Design and Usability (6, October, London)

Both days can be booked from either page. All of our courses (including the above) can be found at

UCD Courses at HCI 2009 and in London

Wednesday, May 13th, 2009

We’re pleased to announce that two of our courses have been accepted for presentation at the annual British HCI Group conference (HCI 2009), this year at the University of Cambridge from 1-5 September. The courses are

  • Innovations in Card Sorting: A Hands-On Approach – this is our half-day workshop on paper-based card sorting using our advanced analysis software, SynCaps V2. (See for further details.)
  • Ajax Design and Usability – a half-day course on how to use Ajax and similar web technologies to improve the user experience rather than to frustrate it.

Both of these courses were very well received at CHI 2009 in Boston last month. They will be available at the HCI 2009 conference in Cambridge on Tuesday 1 September. Half-day courses at the conference will cost only £40 plus, you do not have to register for the conference to attend the courses.

Full details of conference courses can be found at

We will also be running a more extensive one-day course on both paper and online card sorting in London on 5 October. The cost includes a fully-licensed copy of our SynCaps V2 analysis software. For further information and to book online visit

News Summary

Monday, April 27th, 2009

I’m moving news items from my design home page to a new blog category called News (unimaginative, I know). Here is a summary of news for 2008/2009.

We presented three courses and a short paper at the CHI 2009 conference in Boston. This puts us on a par with Carnegie Mellon (who also had three courses but slightly more papers<g>):

  • Innovations in Card Sorting: A Hands-on Approach
  • Web Design for Usability
  • Ajax – Design and Usability

(These courses can also be run in-house. Details are available at

We’ve posted the slides and a recording from our half-our card sorting webinar, plus four videos showing how to prepare for and capture data from card sorting sessions.

The paper concerns a study we conducted using Simon Baron-Cohen’s empathising and systemising quotients. It provides a psychological explanation for the difficulties technologists have in seeing problems from a user’s perspective:

William Hudson was the invited keynote speaker for the CADUI 2008 conference in Albacete (near Madrid). He also presented a half-day tutorial on card sorting. An essay based on his keynote address is available here.

Do you like using or teaching Card, Moran and Newell’s Keystroke Level Model but hate the arithmetic? Treat yourself to our free KLM calculator!

Bandwagon Cues – To Jump or Not to Jump?

Friday, April 24th, 2009

Continuing on the theme of new research from the CHI 2009 conference, I came across another interesting poster – this time from Penn State University (S. Shyam Sundar, Qian Xu and Anne Oeldorf-Hirsch, “Authority vs. Peer: How Interface Cues Influence Users”). Here the researchers were considering the effect of an authoritative logo and customer comments on purchase intention, participants’ product attitudes and a raft of other factors they referred to as “bandwagon perceptions”.

For the studies they used a typical product page, as shown in Figure 1 (adapted from Amazon). The “authority” seal shown (above the camera) was either for a fictitious organisation (Zig! as displayed here) or for CNET, a well-known technology review site (or it was absent altogether). Both seals were fairly similar in appearance.

Typical product page showing Zip! authority seal 

Figure 1: Typical Product Page

The researchers also made use of “outlying reviews” – that is, one where the reviewer expressed dissatisfaction with a product, even though the average score among all reviewers was high. So, in summary, there were two main effects of interest: faux versus “real” authority logo and presence or absence of “outlying” (dissenting) review.

Some of the reported results are as might be expected, but there was one very interesting interaction between the authority seal and an outlying review:

  • When no authority seal was shown, the presence of an outlying review had no effect on purchase intention
  • When the CNET seal was shown, purchase intention was contingent on the absence of an outlying review (that is, an outlying review reduced the likelihood of purchase)
  • When the Zig! Seal was shown, the situation was reversed (that is, an outlying review increased the likelihood of purchase)

The relatioship between the seals and the presence of outliers is shown in Figure 2. Needless to say, this final point – that purchasing intention increase with an outlying review – is somewhat counter-intuitive. The researchers offer no explanation for it and I have none to offer. It would be interesting to know whether other studies show any similar effect. I’ll write more on this if something turns up!

Chart showing negative effect of outlying review with CNET seal and opposite for Zig! seal

Figure 2: Purchasing Intention by Seal Condition and Presence of Outlying Review 

Facial Avoidance in Page Design

Monday, April 20th, 2009

I am a great admirer of Tom Tullis’s work. He’s made important contributions to our understanding of screen design over the years (plus he is even older than me, which gives me great cause for hope!). In a recent poster at CHI 2009, in collaboration with Fidelity Investment colleagues Marisa Siegel and Emily Sun, Tom has done it again. He explained to me their important findings on the use of face images to attract attention on web or intranet pages. The results certainly run contrary to the perceived wisdom in this area (that humans are naturally attracted to facial images).

The Fidelity studies show that not only were users disinclined to look at facial images of the type shown in Figure 1, but that a significant number of users were unable to find the text immediately adjacent when given a task requiring that information.

Box containing facial image next to link text

Figure 1: Link panels with and without facial image (Study II)

In fact, overall performance was negatively affected by the presence of the face: accuracy dropped from 93% to 78%, mean time on task increased from 37 to 54 seconds and perceived task ease dropped from 4.2 to 3.4 (on a 5-point scale).

In a separate study, Tullis and colleagues not only found that facial images reduced performance; they also had the completely unexpected effect of reducing user confidence. Figure 2 shows the quite common approach that was tested (with and without the images). Again accuracy dropped, but this time by a smaller margin, from 94% to 87%. However, trust also dropped, from 6.3 to 6.0 on a 7-point scale. This result may seem small but there is only a 5% probability of it being due only to chance, which is taken by statisticians to mean that it was significant.

 Box show author images next to link text

Figure 2: Authors’ images reduced trust in content (Study III)

So, contrary to what I remember being told in design seminars years ago, and even contrary to advice that I would have given up until I saw these studies (typified by my article on using images as links – it looks like we need to be careful about how we use facial images in particular.

(You can see the full work-in-progress paper in the CHI 2009 proceedings, which will eventually be available from the ACM Digital Library –

User What? How to Alienate Your Colleagues with Live Meeting.

Monday, February 23rd, 2009

I am not a Microsoft basher, or at least I wasn’t until Vista stole a year of my life in its troublesome pre-SP1 version. However, my recent experience with Live Meeting 2007 has me questioning any remaining pro-Microsoft sentiment that I have been nostalgically harbouring.

It was a simple enough problem: set up a half-hour webinar and invite participants without publishing all of their e-mail addresses to everyone attending. With the Live Meeting plug-in, it even looked deceptively simple. The most complicated part appeared to be creating a distribution list to prevent individual e-mails from being shown. But it’s a steep, slippery, downhill slope from there.

The first problem is that Outlook creates a ‘dummy’ message for you to send to attendees. Users are supposed to realise that they can add their own text at the top of the message but the bottom part of the message, where the important details like telephone numbers and Web URLs go, will actually be entirely replaced when the message is sent. So, if you want to correct the phone number (the one supplied had a superfluous zero) or add details for local numbers in other countries, you can just type it all in and then have it discarded without notice. Simple huh? Happily, I discovered that in a test meeting I created beforehand.

For the real meeting, participants were signing up over several days. The initial invitation went out correctly but on opening the calendar entry to add further recipients, I discovered the distribution list was gone, having been replaced by a list of individual e-mail address.  What’s a user supposed to do at that point? Update the distribution list or the calendar entry? I may never know if I guessed wrong, but when I started getting two or three separate acceptance e-mails from participants, I suspected that all was not well.

On checking my Live Meeting account, I discovered to my horror that there were now three separate Live Meetings: the original, plus one for each time I updated the attendee list. They had separate meeting codes, so what would have actually happened on the day is that the lucky attendees who were invited first would get to see and hear about card sorting in its full glory, while those in the other meetings would be in an expensive state of limbo (since the calls and webinar connections were all being charged for through Live Meeting). The only remedy was to send an apology to everyone, cancel all the meetings and start again from scratch.

It may be that some of these problems were caused by the Live Meeting plug-in for Outlook as it’s hard to guess how this functionality is divided. What I do know is that if I try to send invitations from the Live Meeting website, I get precisely the problem I wrote about in my last blog entry: the Microsoft server pretends that it is sending e-mail messages from me and it isn’t authorised by our Sender Policy Framework (SPF) to do that. So any e-mail server doing SPF checking will reject the message as forged. And since the Outlook-based e-mail invitations work so badly, I had to devise my own mail merge and calendar entries to be certain that none of this was going to happen again.

It is almost as if some parts of Microsoft have never heard of user experience. And they’re not the only large organisation with this problem. But they really, really should know better.