6-Daniel Hill

With respect to design, a mental model is pretty much how a user approaches and thinks through the process of using some application or feature of a product. The mental model is what the user believes to be true about some design, whether it is true or not. Human centered computing attempts to create accommodating designs that fit a bulk of the users' mental models. When it comes to the comments section of YouTube, the users might be aware of how to sign in or post, but they may have some difficulty finding specific comments or figuring out how to report a comment that violates rules. It is important to shape a design to the mental model in order to give the users easier access to the features.

An implementation model, on the other hand, is a the bare-boned structure of an application. This is where the guts and actual code of the program might lie. Only the programmers can really know what is going on here. While this can be nice and efficient for the programmers, a user should never be exposed to this kind of a design because a vast majority of them will have no idea how to use it, and they will immediately be taken out of their comfort zone. As a result, they will likely give up on the design as whole. This is why it is important to mask the implementation model with some kind of mental model for the users.