Notes from Dan Saffer (2008). Designing gestural interfaces: Touchscreens and interactive devices. O’Reilly Media, Inc.

Designing interactive gestures: The basics

The design of any product/service should start with the needs of the target user group. We need to ask:

• Who’s the target user group of the product?
• What are the needs the product aims to respond to?

Even novel and innovative gestures are destined to fail if users’ needs are not met! So, the first question to ask before designing a gestural interface for a product is: does this product even need a gestural interface? There can be reasons for both having or not having a gestural interfaces. I list them here:

Why NOT HAVING a gestural interface

1. Heavy data input: keyboard is faster to enter text/numbers;
2. Reliance on the visual: if the stystem does not provide a haptic affordance or feedback and relies only on visual feedback, then a gestural interface may not be appropriate, especially for older adults where vision could be compromised;
3. Reliance on the physical: using a gestural interface is more physically demanding than using a keyboard/screen: some people (e.g., seniors) could not be able to perform a gesture, but also environmental conditions can make it difficult (e.g., touching the screen with gloves in winter). On the other hand, too subtle gestures may also be difficult to perform;
4. Inappropriate for context

Why HAVING a gestural interface

1. More natural interactions: interact with digital objects like you do with physical ones;
2. Less cumbersome or visible hardware: gestural interfaces allow to make the mouse/keyboard disappear;
3. More flexibility: for touch interfaces – they allow to have many controls in a small space. For nontouchscreen gestures, there’s no limit of space;
4. More nuance: the movements of the human body can convey more information than mouse+keyboard (e.g., raised eyebrows, wagging finger, crossed arms);
5. More fun: they are more entertaining