Cable TV. The example is of the remote control of a cable TV
system, which enables turning on and off and changing the channels of both the
TV set and the cable converter. A special button enables the users to set to
either TV or converter mode. The design seems logical and easy to comprehend.
Many users are willing to learn and follow this logic. Yet, many others find it
confusing. They often forget to select the proper mode, resulting in
unintentional turning the converter off, or in setting the TV set in a wrong
channel. Too often they call customer support for help, complaining about phantom
system faults (Harel, 2007).
A simple usability test at the prototype stage
could have revealed the potential user difficulties. A redesign of the remote
control, implementing usability guidelines for direct manipulation and
scenario-based mode-independent operation, based on user task analysis, could
have enabled the design of another remote control, enabling seamless operation
of the TV system. Many other examples can be found in the book by Donald Norman
(2002)