So, for example, design with the language and visual centres of the brain in mind, so that the specific combination of senses that might be engaged work in favour not in conflict with the process.
For example, we can read a map (visual) while receiving instructions on its use (auditory) - as the visual and language centers are distinct.
However, as I discovered yesterday, when I tried to pass on a message to my wife verbally who was in the depths of writing a report to a tight deadline not a word was heard - her language centre was so fully occupied that she shut me out. She didn't even see me come into the room. (She did enjoy the tea and toast though).
The mind's a tricky thing - are we being too clever? We've survived tens of thousands of years without multi-media or e-learning. I reckon the most useful things I have learnt in life were watching my grandfather service a car, put up wallpaper and empty the guttes.