The 2 buttons in the above picture are for a toilet flush. One button does a big flush using lots of water; the other does a smaller flush using less. Using a small flush when that’s all that is needed avoids wasting water and that’s a good thing.
As you can see the 2 buttons are of different sizes. As an interface designer this poses us a problem – which button should trigger which flush? There are 2 options:
- The big button is for a big flush and the small button is for a small flush
- Or, we assume the small flush will be used more often so it should have the bigger button to make it easier to use. The less frequently used big flush can have the smaller button.
The problem is that neither approach is ‘wrong’ – each is a valid implementation. That’s why we test – once we have seen how people naturally interact with our product we know which decision we should take.
The above example is quite trivial but it illustrates the point – for any given interaction there are multiple valid interpretations. If we want our products to be enjoyable we need to know which interpretation the majority of people hold. This is especially important for new products – as we develop them we are totally immersed – living and breathing it every day (and night!). We know how it works. When we created the interface, we could see no other way that it could be interpreted. However, as soon as we see someone use our product for the 1st time, all that certainty can be washed away in an instant.
Testing reveals the truth. We don’t test to be proven right or wrong; we test to see how things are.