the holy grail of usability engineering.
• If we had an accurate model for the way a human
used a computer interface
• we would be able to predict the usability of a
design, without having to
• actually build it
• test it against real people
• measure their behavior.
User interface design would then become more like other fields of
engineering. Civil engineers can use models (of material stress and strain)
to predict the load that can be carried by a bridge; they don’t have to
build it and test it to destruction first. As user interface designers, we’d