Web 2.0 Expo 4 - Gestural/tactile interfaces

Tactile interfaces may not be directly related to web 2.0, but it is, however, in my opinion one of the most interesting developments in user interface design right now.

Here at the Web 2.0 Expo Dan Saffer from Kickerstudio gave a brief introduction to the area of what he called Gestural Interfaces.

First of all, gestural interfaces are not a strange development, because human beings are not really designed to work with a mouse and a keyboard in front of a computer screen. Saffer was quoting David Liddle for saying that: “Wer’e using bodies evolved for hunting, gathering and gratuitous violence for information age tasks like word processing and spreadsheet tweaking.”

Gestural or tactile interfaces are a much more natural way to interact with computers, but these kinds of interfaces creates new challenges.

First of all Saffer talked a bit about the history of touch screens, which basically goes all the way back to the 1970’s. Personally I would actually recommend reading this story in The Economist, which gives a very good overview of the history of touch screens.

But gestural interfaces are more than touch screens. Saffer showed a list of the most common sensors that can be used for gestural interfaces:

• Pressure
• Light
• Proximity
• Acoustic
• Tilt
• motion
• Orientation

When we are starting to use the human body for navigating digital interfaces we need to pay attention to thinks like kinesiology and physiology. Working with computer interfaces and user experience we need to understand the human body and especially the human hands and the human fingers.

Looking at fingers as a navigational tool there are a number of things we should be aware of:

- Fingernails – can be useful but also problematic
- Fake fingernails – are almost always a problem
- Finger oil – greases the screen
- Fingerprints
- (left) handedness
- Accessibility issues
- Wrist support
- Gloves
- Inaccurate (compared to a cursor)
- Attached to a hand aka. Screen coverage (when people are touching with fingers, the hand may end up covering the subject on the screen)

When designing touch interfaces we should generally make sure that the touch target is at least one centimetre wide. There are, however, two tricks to go around this limitation:

1. Iceberg tips: the sensitive area is actually larger than what is seen on the screen
2. Adaptive targets: The interface increases size of targets based on a guess of what the user is going to press (the Iphone does this)

The following standard navigation tools are also problematic in a touch interface, and should be used with care or not at all:

- Cursors
- Mouseovers and hovers
- Double-click
- Right-click
- Selected default buttons
- Undo

Documenting gestures

Saffer talked about some of the problems about documenting touch interfaces in wireframes. Basically he did not have a fixed solution for this, but he recommended many different solutions such as storyboards, architectural visualizations and video clips to document a gestural interface. The problem of course is that true gestural interfaces involves the human body, and therefore the body and its movements need to be part of the documentation of the interface.

Communicating gestures

Another issue concerning gestural interfaces is that people may not even know when they are interacting with a gestural interface. We probably all know the hand dryers or towel dispensers that are operated by an infrared sensor. Sometimes we are simply not aware that the machines are operated by our hand movements, which may result in unsuccessful usage of the dryer or the towel dispenser.

It is therefore important to create gestural interfaces which communicate that they are gestural and at the same time give clues as to how they are operated.

Choosing gestures

Finally Saffer talked about which gestures to choose. He didn’t give any specific advice but kept the advice to the overall conclusion that gestures should be chosen based on three things:

1. The avilable sensors
2. The task that needs to be performed
3. The physiology of the human body

Besides that it is important that the complexity of the gesture should match the complexity of the task at hand, which basically means that very simple commands should also be matched by very simple bodily gestures.