Performance model
The programmer or designer creates the behavior appearance of the software to show outward. This display does not require accurate performance in the computer, although unfortunately, many software often express themselves. Whether it can express the function of the computer does not rely on the real line of the computer, this is more obvious in the software than other media. This makes smart designers to hide some software that is actually a nasty detail of work. This implementation and exhibited separation introduces the third model of the digital world, and the designer's performance model - the designer selects the functionality of the program to the user. Donald Norman (1989) is a briefly known as the designer model. In the software world, the performance model of the program can be (often) and the actual processing structure is quite different. For example, the operating system allows the network file server to look like a local hard drive. The model does not exhibit a physical hard disk that may be actually outside. The concept of a model is in the mechanical world. There is no popular copy. The link between the three models is shown in Figure 2-1.
Figure 2-1: Engineers often construct software by various technologies and commercial insurance. The model regarding how the software actually works is called realization model. The user thinks that they need to do and the procedure should help them, this is their psychological model with software interaction. This is based on how they work for them and how the computer should work. The designer chooses to express the work of the program to the user's way, not like two other models, it is a software designer can have a large level of control. One of the most important goals of designers should be to make the performance model as much as possible close to the user's psychological model. So the designer understands the details of the target customers about how they use software work.
The closer the performance model and the user's psychological model, the easier if the user can learn to use the program and understand it. In general, a performance model that is too close to achieving the model will be significantly reduced to weaken the ability to learn and use the program, which can be considered (mostly in most cases) The psychological model of the task is different from the software implementation model. of. We tend to establish a simple psychological model than the real situation; so if we make the expression model simpler than the real realization model, you can help users better understand. For example, when you step on the brakes in the car, the possible psychological imagination is to route a lever and wheels to slow down. The actual mechanism is to include hydraulic steel, pipeline, as well as a metal gasket on the perforated disc (possibly knowing the car's friends will be more clear), we have simplified these in your mind, created It is less accurate but more effective psychological model. In the software situation, we imagine that the new plaid scroll into the screen when clicking on the electronic tab meter scroll bar. In fact, there is no scrolling at all. There is no group of forms there, but a numerical data structure, there are many pointers, and the program is synthesized from the new screen. Understanding how the software is actually working hard to help people use it, but this understanding is required. The expression model allows the software's creator to express how software works in a simplified way to solve this problem. This cost is the amount of software, and users will never need to know. The user interface should give up the realization model, the better the effect of the psychological model.
The axiom user interface should ignore the realization of the model and close the user's psychological model.
In Adobe Photoshop, users can adjust the color balance and brightness of the image through a function called change (VARIATION). It does not display some numeric fields of input color values as in ways to implement models, but show a set of thumbnails, each with different color balances (see Figure 2-2). Users can click most desired color settings. This interface is more compliant with the user's psychological model because users like graphic designers think about the effect of graphics, not a group of abstract numbers.
Figure 2-2: Adobe Photoshop has a good example to illustrate design software to comply with the user's psychological model. The change interface displays a thumbnail of different colors balance and brightness with adjustable increments. Users can click to select graphics that can be easier for desired. This picture will become the default value of the new different thumbnails. This interface follows the psychological model of graphic designers, and they consider fine visual effects, not a group of abstract values. If the software model is very close to the user's psychological model, it will exclude complexity in the user interface, and the cognitive framework provided by the interface allows the user how to achieve his goals and needs. Africher target directive interaction reflects the user's psychological model.
The user's psychological model does not need to be true or correct, but it should make the user more effectively. For example, a lot of computer users who don't understand technology will imagine the screen is the heart of the computer. This is very natural, because they look at the screen all day, and only by the screen can see what the computer is doing. If you point out a user, the computer is actually a silicon chip in the black box under the table. He probably shrugged the knowledge that there is no significance (for him). Different from the CPU and display cannot help him think about how to operate your computer, although it is technically correct.
