When we talk about design, we usually talk about appearance. More specifically, we talk about appearance at one specific point in time. But what about the fourth dimenson? What if we could design the perception of time just as we can design the perception of space?
Attention, Causality and Context
The physical world around us doesn't feature jumpy behavior or sudden change of state. It is not possible for the chair you are sitting on to suddenly disappear and reappear on the other side of the table. It is however entirely possible that you stand up and move the chair there. That's a transition. Transitions satisfy our dire need for causality in life. Not only do they clarify what is happening, they also provide the essential how and why.
In addition, motion is one of the most powerful ways to direct attention. Evolution has designed us so that we are just really, really good at recognizing motion. What has helped our ancestors to spot predators also helps us today to see when things in a user interface are changing. One of the less intuitive characteristics of this trait is that we recognize motion even faster when it occurs in our peripheral field of vision rather than in the center. This makes it a perfect tool for things like notifications.
Designing the Perception of Time
You may have seen optical illusions like this one, where the lines appear slanted or curved while they really are perfectly straight.
While those illusions are common knowledge by now, it is less well known that our perception of time can be mislead pretty easily as well. In particular, there are three factors that influence how long we perceive a timespan to be.
- The kind of motion that occurs
- Our preconceptions of how long a process should take (priming)
- The emotional state we are in during that process
In particular, this is about the peak-end rule. It says that we remember the intensity of something by looking at just the most intense moment and at the intensity at the end. This means, that e.g. load bars and progress indicators that speed up towards the end have a psychological advantage in terms of performance.
Our expectations set the stage for anything that we experience. The perception of time is no different here. It is perfectly acceptable to wait a couple of seconds for an app to download. But when typing in that app delays every keystroke by a few seconds, it becomes unusable.
This is one of the most interesting things I have ever learned. Research shows that our memory of a period of time varies depending on how we feel during that time. Anxiety and fear make the timespan appear longer than it actually was. This effectively means that managing emotion in user interfaces has much broader implications than simply »joy of use«. It can actually influence the perception of application speed.
You cannot not design
The crux about all these phenomena is, that they happen regardless of our intentions as designers. Whenever we create something without taking the effects of time into consideration, we are simply leaving the outcome up to chance. The active and intentional design of time perception is still a rather new field. On the one hand that means that there aren't many established patterns that one can easily follow. But on the other hand, it also means that it is an exciting field with lots of opportunities.