6- Martin Johnson

 The feature we redesigned on YouTube was the display of the video player upon conclusion of a video. The screen shows 12 boxes with a screen shot and absolutely no other information. The mental model held by the user here is that these 12 boxes each represent a related YouTube video to play. It is that simple. We kept the same format of using the boxes (because they have this mental model), but we organized them on the side. We also had one box with a countdown. Almost everyone associates this with an automatic start made popular by video streaming sites and apps.

This mental model contrasts with the implementation model because the user doesn't have to think about any underlying issues. They see 12 relatable boxes and already know what they represent. This is because their mental model of a YouTube video lets them know that these are videos as well. If the implementation model had been used, there wouldn't have been much user-design at all. People would need to have an understanding of HTML and how to navigate for themselves.