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88 Chapter 3 Understanding users

Reading can be quicker than speaking or listening, as written text can be
rapidly scanned in ways not possible when listening to serially presented spo-
ken words.
Listening requires less cognitive effort than reading or speaking. Children,
especially, often prefer to listen to narratives provided in multimedia or web-
based learning material than to read the equivalent text online.
Written language tends to be grammatical while spoken language is often
ungrammatical. For example, people often start a sentence and stop in mid-
sentence, letting someone else start speaking.
There are marked differences between people in their ability to use lan-
guage. Some people prefer reading to listening, while others prefer listening.
Likewise, some people prefer speaking to writing and vice versa.
Dyslexics have difficulties understanding and recognizing written words,
making it hard for them to write grammatical sentences and spell correctly.
People who are hard of hearing or hard of seeing are also restricted in the
way they can process language.
Many applications have been developed either to capitalize on people's reading,
writing and listening skills, or to support or replace them where they lack or have
difficulty with them. These include:
interactive books and web-based material that help people to read or learn
foreign languages
speech-recognition systems that allow users to provide instructions via spo-
ken commands (e.g., word-processing dictation, home control devices that
respond to vocalized requests)
speech-output systems that use artificially generated speech (e.g., written-
text-to-speech systems for the blind)
natural-language systems that enable users to type in questions and give
text-based responses (e.g., Ask Jeeves search engine)
cognitive aids that help people who find it difficult to read, write, and speak.
A number of special interfaces have been developed for people who have
problems with reading, writing, and speaking (e.g., see Edwards, 1992).
various input and output devices that allow people with various disabili-
ties to have access to the web and use word processors and other software
packages
Helen Petrie and her team at the Sensory Disabilities Research Lab in the UK
have been developing various interaction techniques to allow blind people to ac-
cess the web and other graphical representations, through the use of auditory navi-
gation and tactile diagrams.
Problem-solving, planning, reasoning and decision-making are all cognitive
processes involving reflective cognition. They include thinking about what to do,
what the options are, and what the consequences might be of carrying out a given
action. They often involve conscious processes (being aware of what one is thinking