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1.5 The goals of interaction design 17

accomplish. A key concern is determining how much time users are prepared to
spend learning a system. There seems little point in developing a range of function-
ality if the majority of users are unable or not prepared to spend time learning how
to use it.
Question: How easy is it and how long does it take (i) to get started using a sys-
tem to perform core tasks and (ii) to learn the range of operations to perform a
wider set of tasks?
Memorability refers to how easy a system is to remember how to use, once
learned. This is especially important for interactive systems that are used infre-
quently. If users haven't used a system or an operation for a few months or longer,
they should be able to remember or at least rapidly be reminded how to use it.
Users shouldn't have to keep relearning how to carry out tasks. Unfortunately, this
tends to happen when the operations required to be learned are obscure, illogical,
or poorly sequenced. Users need to be helped to remember how to do tasks. There
are many ways of designing the interaction to support this. For example, users can
be helped to remember the sequence of operations at different stages of a task
through meaningful icons, command names, and menu options. Also, structuring
options and icons so they are placed in relevant categories of options (e.g., placing
all the drawing tools in the same place on the screen) can help the user remember
where to look to find a particular tool at a given stage of a task.
Question: What kinds of interface support have been provided to help users re-
member how to carry out tasks, especially for systems and operations that are used
infrequently?

How long do you think it should take to learn how to use the following interactive products
and how long does it actually take most people to learn them? How memorable are they?
(a) using a VCR to play a video
(b) using a VCR to pre-record two programs
(c) using an authoring tool to create a website

Comment (a) To play a video should be as simple as turning the radio on, should take less than 30
seconds to work out, and then should be straightforward to do subsequently. Most
people are able to fathom how to play a video. However, some systems require the
user to switch to the "video" channel using one or two remote control devices, select-
ing from a choice of 50 or more channels. Other settings may also need to be config-
ured before the video will play. Most people are able to remember how to play a video
once they have used a particular VCR.
(b) This is a more complex operation and should take a couple of minutes to learn how to
do and to check that the programming is correct. In reality, many VCRs are so poorly
designed that 80% of the population is unable to accomplish this task, despite several
attempts. Very few people remember how to pre-record a program, largely because
the interaction required to do this is poorly designed, with poor or no feedback, and is
often illogical from the user's perspective. Of those, only a few will bother to go
through the manual again.