This assumption is entirely wrong. The designer is already very familiar with the use of the device. He or she can immediately call to mind how to use the device, or what the manual intends to convey. Thus, the designer will have no way of spotting ambiguities. Furthermore, the designer probably has an emotional investment in the design, and will therefore have to fight his natural defensiveness to spot flaws.
Consistent practice is necessary to produce automaticity.
Difficult skill learning will transfer to very different tasks using the same faculty. It says that increased arousal causes a narrowing of attention. Give an example of the Sequence of Use Principle . Performance in choice RT tasks is not as badly impaired as it would be by loud noise alone, or by sleep deprivation alone.