Interactions - September/October 2008

to be used one-handed? What controls can people comfortably reach?

• Functional Complexity: Everyone wants a “simple” set of controls, but it is important to include enough command vectors to support the required feature set. This is explained in more detail below, as it is a critical step for interaction designers.

Emotional factors to consider:

• Perception: how will the product look on a shelf or in an advertisement? Currently, fewer controls make for a more appealing product (though this hasn’t always been the case). When a product looks simple, people focus more on aesthetic details. Customer perception is also crucial to adoption, and emphasizing a simple appearance increases the chance people will buy it. The designer then must balance the eventual usability of the product with that simple appearance.

• Differentiation: if the product is in a well-defined category, success might mean breaking away from the known paradigm.

• Iconic appearance: especially for products in a new or redefined category, controls will be like facial features that make the product instantly recognizable.

• Approachability: consider the audience and whether they will be comforted by familiar controls that they know from other devices, or whether that is distracting.

Reviewing this list will likely— and hopefully—generate lots of questions. It is then useful to task different team members with conducting appropriate research to help evaluate different options against these various factors.

It’s also worth discussing which considerations are more binding than others. Often the engineering team members will focus on hard constraints, where the design team will focus on the emotional and user needs. Involving the business decision makers in reviewing these considerations will help answer some key questions. How important is cost in relation to size? How important are the aesthetic elements to the brand?

How Much Control Is Enough?

For the interaction design team, a key step is identifying core product functionality that will demand the most from the control set. At this point, it is important to consider how much benefit a particular piece of functionality yields.

As an example, LUNAR recently designed the PASCO Spark. This product helps students in grades 6–12 learn scientific principles by using sensors to observe and visualize scientific phenomena. We knew that the user’s need for simplicity, durability, and a large screen outweighed the needs for fine control or lots of data entry, which might not be immediately apparent when discussing a scientific tool.