to be used one-handed? What
controls can people comfortably
• 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
• 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
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
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.
In order to support our
instincts for simplicity, we
mapped out different characteristics of the product against
what different users would need.
This led to an important
design decision: While it might
make some complex interactions challenging, a single button
September + October 2008