I’ve talked a bit on this column about media design and how important it is to design media and systems bearing in mind the needs of users. Some of you may think this common sense. Of course we design things to be used. But there’s a whole area of scholarship behind human-computer interaction, and sometimes there may even be contradictions between theories of HCI, interactive entertainment and interactive art.
I’ve tried to understand the whole deal about human-computer interaction, but due to limited access to scholarly documents about the field, can’t say anything vaguely legible about this. However, Wikipedia tells me that ignoring HCI can lead to disastrous consequences, such as the Three-Mile Island incident.
The Three-Mile Island accident was a partial nuclear meltdown on one of the two Three-Mile Island reactors in 1979. Aside from the engineering problems that emerged from the incident, part of the reason attributed to this power plant catastrophe is the ambiguous control room indicators in the power plant’s user interface. In fact, the worker misinterpreted the indicator and manually made it worse by doing the opposite of what he was supposed to do. Even though this was a 1979 incident, and supposedly unrelated to the modern intellectual human today, accidents in aviation still occur when new and apparently “better” programs are used, and pilots still operate them with the old system interface in mind. This is, as you would know from reading previous entries, a problem with conceptual models.
Christopher Wickens came up with a whopping 13 principles of display design to make the user experience that much more fulfilled.
1. Make displays legible. Duh.
2. Avoid absolute judgment limits. I’m not quite sure if I understand this correctly, but it suggests against asking users to determine the level of a variable based on another sensory variable, such as colour or size, because user perception may vary.
3. Top-down processing. Users have certain expectations of what they see, and they may be blind to changes contrary to what they expect. This means that if something is wrong, make it very very clear to the user, or else they will overlook it.
4. Redundancy gain. This is one of the models that encourage redundancy. Present a signal in many forms to ensure that users really understand what is going on. For instance, aside from flashing a red light, include an emergency siren sound to ensure that users really know there is an emergency. This is the same design for traffic lights, because both the light colour and the position of the light indicate the same thing.
5. Similarity causes confusion. Users cannot tell the difference between AJDGE#𑾠 and AJDGE#*#73633. Ensure that differences stand out.
6. Principle of pictorial realism. Make sure that pictorial displays are intuitive. If temperature is high, show a thermometer with a high temperature indicator, just as what would happen in reality.
7. Principle of the moving part. When something is moving, let it move as it would in reality, in concert with the user’s mental model. It should slow down as it moves higher or reaches its destination, for example.
8. Minimising information access cost. When you’re sure that users will require information from other sources together with this one, try to put them close together so the user doesn’t need to switch around.
9. Proximity compatibility principle. While Number 8 was about physical proximity, this one seems to talk about mental proximity, that users can link concepts between two information sources closely and easily.
10. Principle of multiple resources. Users can process information from two different sources more easily than processing things one by one in the same source, so try to integrate pictures and sound rather than presenting all pictures first followed by all sounds.
11. Replace memory with visual information. Users should not have to rely too much on memory to enter commands. Provide a list of available commands for them to refer to.
12. Principle of predictive aiding. Try to provide clues on what will happen later on so that users can think about them now. Something like how road signs indicate the distance to a particular town.
13. Principle of consistency. This is of course most important, and what designers easily overlook. New programs should be compatible with what users have already been doing. This may be the reason why the QWERTY keyboard’s still so popular today.
And guess what, this is only about display. I haven’t even begun to delve into the operations of systems. So you can see that in the design of any software or hardware, you need a specialised user designer to ensure that everything is communicated effectively to users before products are released into the market.
The cool thing is that human-computer interface combines multiple aspects, from computing and media studies to cognitive psychology and visual arts. This is a domain that may truly integrate the knowledge of the world in ways we thought were completely disparate before.