We'd like to make tacit things, things we know, *explicit*. One of the ways to do that is through making comparisons, to look at the distinctions between things. So, let's look at simple comparisons. The simplest one is just to look at two things. It might be two documents; it might be two systems; it might be two solutions to the same problem – perhaps two different kinds of menu in the system we're looking at.
So, you look at them and then you just ask simple questions: What's the same? What's different between them? And it's the difference which is often the interesting things. It's easy to – when you say they're the same – you know – these are both fruit; that doesn't tell you that much. But what's so different between an apple and an orange? What's so different between the kind of menu you get on a phone as opposed to the kind of menu you get on a web page? And by talking about those distinctions and those differences, you start to *make sense and understand things about them*. So, sometimes that can happen on simple two-way comparisons.
Sometimes, a *three-way comparison* can be a bit more helpful. So, when you have two things to compare, sometimes it's easy to fall back into standard differences. So, again, with my apple and orange, I might just say, 'Well, this is a citrus fruit and this isn't.' or something like that. So, I have a set of standard categories. This is sort of top-down reasoning, going from book knowledge, rather than from sort of bottom-up reasoning. Three-way comparisons can help here sometimes to actually say, 'In what way is this like this but different from something else?'
And sometimes you can deliberately play with this, try different orders so the obvious answer is taken away from you. The origins of this are in repertory grid techniques which are used for personality tests. And they're used to ask people three-way comparisons as a way of sort of finding out about the way their personality is. However, you can use it for all sorts of kinds of technique. You can use it yourself to look at techniques and ask yourself this question,
or you can use it with your users. So, here's an example we'll go back to the apples and orange. So, I've brought my fruit bowl, if it can't fall out. And in my fruit bowl I've got some grapes, I've got an orange, I've got an apple. What you might do is say, 'Okay, I've got an apple and orange. How are an apple and orange similar to one another but different from grapes?' And you could probably already start to think of answers yourselves. We have different answers because this is about exposing our tacit distinctions.
So, you might apply this – if you're working with fruit manufacturers, you might ask this question, but obviously for user experience, this might be two different, three different menu systems. And so, for these apples and oranges I might think about something like *size*. So, these are bigger than – well, certainly than an individual grape, not necessarily than the whole bunch, but an apple and orange are bigger than single grapes. You might use size as a distinction. But you notice it's interesting even there, I've started to have to talk about some
subtlety in here, which is often the case. Do you eat one or many? So, typically when you have an apple or orange, you just have one apple or one orange, but when you have grapes, you usually don't have just one grape – you usually have several, partly because they're smaller. But actually, because they're smaller, we're already seeing interesting relationships. Obviously, if you have something small, you eat more of them. I've said they're not in wine – okay, you know, you make wine out of grapes. That's an odd one because I could say that – you know – apples you can make cider with, all sorts of things.
But obviously, I think grapes are so closely associated with wine in my head, that seems sensible for me given my distinction. So, this is obviously exposing not just what these differences are, but actually about the *way that I see the world* – the categories I impose on the world. So, we expose the categories that we have there by making these distinctions. And so, one of the interesting things is when you have – if you just do it one way round, obviously you can again sometimes drop into standard links,
and perhaps in my head I put apples and oranges closer to themselves than I do to grapes. But I can break that by deliberately mixing things up. So, now I can say, 'Okay, given an orange and a grape or oranges and grapes, how are they more similar to one another than they are to apples? How is an apple different from them?' So, now I can't use the set of distinctions I had before, so I'm forced to think of new ways. So, again, if I was doing my menus and buttons and web links,
I'm going to start thinking, 'How is' – I can't remember, I have to put labels on these, but – you know – 'How is my web link different from my buttons and menus?' But then having done that, I shuffle them around and I can't use the same distinctions. I've got to think of new differences. Being in Britain, I think about things that I associate more with being things that are grown in Britain. I still think of apples as a typical British fruit. Now, it's interesting – so, before I was thinking about the eating qualities of these,
when I was doing another comparison. Now, I've been forced to think about where they're grown, and also that this was not a hard distinction; notice – you know – this was more easily grown. And probably it's more like I've created a dimension where apples are at one end and oranges another and grapes sitting in the middle. I've sort of – so, having said that I eat one of the other fruits, I've sort of put these into another similar category, saying, 'Well, actually, when I open the orange, there's multiple
segments, just like there's multiple fruits here; whereas the apple is an apple.' – you know. If you cut it up, the core inside is segmented but the actual flesh is continuous. So, that's another distinction. And then, of course, you force yourself again. You say, 'Okay. Okay, I've done the other comparisons. What about putting apples with grapes and oranges on their own?' And, again, I found a different set of distinctions there. For some reason, when you go to visit somebody in hospital, you tend to think of bringing apples or grapes, but not so much oranges – even though an orange has got lots of vitamin C in it.
I think part of the reason is about *messiness*. You know – these are good lunchbox foods. You know – you can eat your apple; you can pull off your peel. It's harder, unless you get those easy-peel oranges, to have an orange in your lunchbox because when you cut it, it spurts everywhere. And – oh yeah – that was another thought, what I thought was these two I eat the skin of. You can eat the skin of an orange, but most people don't. So, you notice what we've done here is we've *pulled out a whole different set of distinctions*.
We've got things about the nature of the flesh in the fruits; we've got the nature of the skins; we've got the size of them; we've got where they're grown. It's a whole lot of different things we're understanding about fruit by doing these sets of comparisons with these three fruit. Typically, the closer the things are you're trying to do these comparisons – that's whether you're doing a two-way comparison or a three-way comparison like this –
the *closer* things are to one another, the *more interesting you get the results* because you're forced to make finer and finer distinctions and that exposes more interesting things about the domain. So, comparing buttons and menus, if you're not careful, you'll fall again into standard categories. Comparing two relatively similar menu systems with each other, you probably start to get some more interesting distinctions out that help you learn about your domain. So, yes, I was giving an example here – oranges and apples;
maybe you learn more about fruit than if you compare an orange with a car, because an orange is a fruit, a car isn't. So, the closer they are, the harder it is to fall into standard distinctions. Having said that, maybe you'll find some interesting things if you look at an apple and say, 'Is an apple more like a tractor or a train?' And this is, I guess, close to sort of bad ideas thinking. Or – you know – sometimes you're asked perhaps, 'What fruit are you like?'
You know – if you go around the people you know in the office, if you were going to give each person a fruit that represented them, which would it be? And then ask yourself *why*. So, if I'm going to say an apple is more like a tractor, is that because tractors are more agricultural? Or maybe I think it's more like a train because perhaps as a child if I went on train trips, I always had an apple to eat while we were on the train. So, by making these, again, closer is often better, but sometimes you make those wild comparisons – you also end up with some interesting things.