1. Describe three principles of direct manipulation.

The first principle of direct manipulation is, “continuous representations of the objects and actions of interest with meaningful visual metaphors.” This means that while interacting with the system, there should always be visual feedback that coincides with what you are trying to accomplish with the interface. The second is, “physical actions or presses of labeled buttons, instead of complex syntax.” This means that instead of giving the user a language or another tool for communication with the system, the system should have an interface that reflects real-life controls, such as physical buttons or actions. The third is, “rapid, incremental, reversible actions whose effects on the objects of interest are visible immediately.” This means that changes should occur in real-time, but be undoable in order to give the user maximum control.

  1. Give four benefits of direct manipulation. Also list four problems of direct manipulation.

One benefit of direct manipulation is that it reflects the real world so users should, ideally, already know how to interact with it. Another benefit is that direct manipulation systems make you feel more in control because they respond faster. Furthermore, direct manipulation systems also try to take advantage of as many of your senses as possible so that you feel more connected to it. One more benefit is that user satisfaction increases because the user feels more in control of the outcome.

One problem of direct manipulation is that sometimes it leads to overcomplicating the system. For example, sometimes text is the most efficient interface to interact with. Also, direct manipulation systems generally consume all of the user’s focus so that they cannot use multiple programs at once. Furthermore, sometimes the visual representations used by the system are not intuitive, so users have to learn them.

  1. Examining the success of video games can provide insight for interface designers. Explain what lessons can be learned by videogames for interface design, but also provide examples of areas where it is ineffective to do so.

Videogames have mastered the art of using 3D worlds as an interface. Therefore, it would be beneficial to look at videogames as an example of good 3D representations. However, videogames are entertainment programs and not practical devices, so they are not as good models for how to make a practical system.

  1. An airline company is designing a new on-line reservation system. They want to add some direct-manipulation features. For example, they would like customers to click a map to specify the departure cities and the destinations, and to click on the calendar to indicate their schedules. From your point of view, list four benefits and four problems of the new idea compared with their old system, which required the customer to do the job by typing text.

Four advantages of the map and calendar is that 1. Many users might find it more intuitive to navigate the interface this way. 2. Some users might not know the name of the airport they need to go to, so they can see all airports in the region they want to travel to and then click it. 3. The calendar could help them precisely choose the date and time they would like to travel. 4. The calendar could help prevent them from mis-scheduling.

Four disadvantages are 1. It would in some cases be faster to select the correct airport from a list. 2. It would be faster in some case to manually type in the time and date you’d like to travel. 3. It might be harder to find the correct airport from a map. 4. People might choose the wrong time and date from a calendar.

  1. List a few guidelines for an effective 3D interface:

An effective 3D interface has instant feedback, logical representations.

  1. List an example of teleoperation or virtual reality. Consider what a future application (that does not presently exist) might do. Be creative!