While you are driving a car, you do the followings in parallel.
- watch forward of the read, get feedback of your action
- hear outside sounds
- manipulate handle by hand and brake/accelerator bu foot
- talk with passenger seat person
You sight organ, audio organ, and body motor systems are working in parallel, even two parts of body motor systems are working in parallel, and you can achieve your goal to get some place.
How wonderful the power of the human being is!
On the contrarily, current human computer interaction is very limited and naive. It doesn’t take advantage of the human power as above: You give information only by hand, and get information only by sight of 2D, serially. Voice interaction is going to add another channel b/w human and machine, but the channel is isolated from the others.