If a system looks difficult to use, people will not go near it in the first place. But if it appears too simple, even after the visitor has explored it a little, he will be bored and leave it behind quickly.
A simple impression is important to make a system look non-intimidating and inviting, especially for novices. Somebody who does not feel at home with operating computers or other devices will shy away from using a system that looks complex and only usable for experts. A multitude of initial options, features, and information will keep non-experts from even approaching your system, and you have no chance of even trying to deliver your message with your system to those people.
But after the initial contact, to keep your visitors engaged, your exhibit needs to convey its depth of features and contents as well. Once the visitor has started to explore the system and interact with it, it needs to show that it has more to offer, and that there are more rewarding experiences to be expected if the user interacts with the system for a while. If the system does not seem to have anything more to offer, then the user will think that it does not make sense to spend any more time with it. The message that you wanted to convey with your exhibit may not have been delivered yet.
These two forces contradict each other. To balance them, a system needs to gradually reveal its complexity to the user.
The WorldBeat exhibit has a very simple main selection screen from where the user starts to explore the exhibit. It only contains short names and icons for the various features of WorldBeat: composing, conducting, improvising, etc. Only when the visitor moves the cursor of his infrared baton over one of these items, a short phrase explains what to expect behind this button. Finally, only when the visitor actually clicks on this button, the system switches to the new page (subscreen) where the feature can be tried out and explored in detail.
Even most desktop GUIs initially show a menu bar only. Nowadays, many applications can be used with hardly using the actual menu entries that are hidden behind that bar. Only if the user clicks onto a menu, the actual multitude of commands available becomes visible. Even more complex settings only appear in dialogues when the user issues commands that require those settings.
Initially, only present a concise and simple overview of the system's functionality. When the user actively shows interest in a certain part of this overview, offer additional information about it, revealing in successive stages what lies behind the initial presentation.
An additional stage of Incremental Revealing, between the initial page and the subsequent page, can be easily inserted by using Dynamic Descriptors which show what lies behind a user interface object without the user having to actually use it (see the WorldBeat example, or MacOS Balloon Help). It will also be easier to implement Incremental Revealing when you arrange the contents of your interactive exhibit into a Flat & Narrow Tree structure. Finally, make sure to provide an opportunity to get back from the more complex parts to the initial easy overview (Closed Loop), so the visitor knows that he has understood this part of the exhibit (Deliver Message)....
Author: Jan O. Borchers