Bill Verplank is a human factors engineer. In the final video on interactive design, he talks about art, design, craft, and the way he looks at interactive design. Bill Verplank uses drawings to document everything. He says that drawing is very important to him because it helps him to remember these things and also helps to summarize ideas.
According to the video , the designer should know how does the user feels, do and know.Before making the product the designer should know what’s the goal, how will they accomplish, what type of feedback they require, do they have the knowledge, Is it cost-effective, what are the things I can control. And the result of interaction design is displays, controls and the behaviors that connect them .