Human-Computer Interaction 3e Dix, Finlay, Abowd, Beale

exercises  -  4. paradigms


Choose one of the people mentioned in this chapter, or another important figure in the history of HCI, and create a Web page biography on this individual. Try to get at least one picture of your subject, and find out about their life and work, with particular reference to their contribution to HCI.


open-ended research



Choose one paradigm of interaction and find three specific examples of it, not included in this chapter. Compare these three - can you identify any general principles of interaction that are embodied in each of your examples (see Chapter 7 for example principles)?

answer available for tutors only

There are clearly a variety of ways a student may answer this question, depending on which paradigm is chosen as a focus. It may be difficult for students to think about how older paradigms presented in the textbook might have modern examples. For example, what would be a modern example of a time-sharing system? Expect that students will feel more comfortable with the later examples of paradigms for this exercise. Also, when this part of the book was originally written, the paradigms/historical section was immediately followed by a discussion of principles of interaction. Therefore, it is reasonable to have students consider this question after having read and understood Chapter 7 of the 3rd edition.

Here is an example answer. We will consider the use of metaphor. Metaphors are introduced to support the general learnability principle. Here are some examples of the use of metaphor:

1) The electronic spreadsheet. This is a fairly old, but classic example of the use of metaphor that resulted in a major "killer app" for personal computers. Before electronic spreadsheets, it was traditional to keep various accounting tasks on large ledger sheets, which facilitated row and column tabulation. Columns of numbers could be easily lined up for mathematical operations performed by hand. The row and column metaphor of the ledger sheet (or physical spreadsheet) was replicated in the original electronic spreadsheet programs introduced in the early 1980s (Lotus 1-2-3 and Microsoft's Multiplan). One specific principle of learnability that the spreadsheet supports is synthesizability. Spreadsheets are very good at supporting "what if" calculations. A complicated series of calculations (like determining monthly expected expenses for a family) oftentimes depends on various parameters (e.g., how many times will the family dine out or how many times will the car need refueling). The calculation can be easily parameterized with a number of arguments and the value of the argument can be changed, resulting in a new answer to the overall question. Whenever the user changes the value of some parameter, by changing the value in a "cell" of the spreadsheet, all dependent calculations are performed and the overall spreadsheet is updated. This makes it easy for an individual to synthesize the effect of the change he just made. Spreadsheets became very popular as simplified programming environments, initially for numerical calculations in financial applications. Over time, just as with the word processor, the metaphor to the original paper spreadsheet has been broken, and the kinds of things we do with an electronic spreadsheet (like perform complicated searches of a database of records) do not even have a clear relationship with the physical world.

2) Web shopping cart. Online shopping is a big application for the world wide web. Initial interfaces often made it difficult for individuals to understand how to purchase multiple items. By introducing the notion of a shopping cart, designers could leverage a familiar "brick and mortar" metaphor for shopping: place items in a cart and then proceed to checkout when shopping complete. This user of a metaphor leverages off familiarity to enhance learnability.

3) Electronic diaries or electronic calendars. One of the most popular PDA applications is for diary or calendar management. Paper-based calendars serve as a good metaphor for most electronic interfaces and again leverage familiarity.

4) Electronic whiteboards, like the LiveBoard or SmartBoard. These typically have an upright display that can be written upon with a stylus. The SmartBoard is a particularly good example of applying the metaphor of a traditional whiteboard, having separate "markers" for writing in different colors, even though this is not strictly needed in the electronic domain. Some even provide a special utensil for erasing. Some electronic whiteboards actually leverage the surface of a regular whiteboard and allow the use of regular markers (with special holders) to make the user feel even more comfortable with a familiar writing experience.



What new paradigms do you think may be significant in the future of interactive computing?

answer available for tutors only

This is a fairly open ended question, but you are looking for students to explore how new technologies might change the way we perceive our relationship with computing. For example, a lot of new technologies are allowing us to extract signals from humans, such as brain waves or other biometric signals, and convert them into input. These technologies are being applied mainly to allow for more universal access for people with disabilities, but you can imagine, both positively and negatively, how interpreting these very implicit signals from humans might change our attitudes towards computing.



A truly ubiquitous computing experience would require the spread of computational capabilities literally everywhere. Another way to achieve ubiquity is to carry all of your computational need with you everywhere, all the time. The field of wearable computing explores this interaction paradigm. How do you think the first-person emphasis of wearable computing compares with the third-person, or environmental, emphasis of ubiquitous computing? What impact would there be on context-aware computing if all of the sensors were attached to the individual instead of embedded in the environment?

answer available for tutors only

Many privacy arguments work in favor of a wearable, first-person perspective on sensing. When the sensing is based on the individual, then there is a chance the individual can limit the spread of information about himself. Community-based services, however, would require getting information into some centralized place, and there is more of an advantage for doing this with an environmental approach. It is also possible when anchoring sensing on the individual that that person might aid in the correct interpretation of the information.


EXERCISE 4.5 [extra - not in book]

Ubiquitous computing has been developing extremely rapidly and will undoubtedly become one of the most significant paradigms over the next decade. This means that some of the systems described in section 4.2.14 of Human-Computer Interaction will be superseded already.

(a) Look around your home, workplace, and personal belongings, talk to your friends and look in magazines and catalogues. List the examples of ubiquitous computing devices you find. (Don't forget the more humble ones like mobile phones.)

(b) Use the web and other sources to find novel uses of ubiquitous computing that are currently being developed. (For some initial pointers see the textbook's web links for chapters 4 & 20)

answer available for tutors only

open-ended investigation


EXERCISE 4.6 [extra - not in book]

Some of the changes in the interactive experience occur many years after the relevant technology was invented. Look at some of the trends discussed in this chapter and track the lag from technology invention to popular impact on the interactive experience.

answer available for tutors only

For example, the WIMP interface didn't gain popular appeal until the mid-1980s, more than a decade after all of the relevant technologies had been invented. Networking of computers was introduced in the early 1960s, but active use of collaborative applications, like email and chat, did not attain mass appeal until the early 1990s. Sutherlands work in the early 1960s on creating manipulable objects on a video display unit became the inspiration for graphical user interfaces (see WIMP) as well as virtual reality, which did not become an important research topic until the early 1990s and made its way into the entertainment industry in the late 1990s. Vannevar Bush's vision of the memex was a foreshadowing of a lot of the hypertext research, which began in the mid-1960s with Ted Nelson. Hypertext became a popular research topic in the mid-1980s. It was not until the advent of the simple graphical interfaces of browsers for the world wide web in the early 1990s that nonlinear-branching hypertext became an important information modelling and dissemination form.


EXERCISE 4.7 [extra - not in book]

As we move into a highly mobile information environment, with network-enabled phones, should we expect new interaction paradigms to emerge?

answer available for tutors only

This is an interesting question, because on the one hand, constant connectivity is not something we expect today and it may very well change how we think about information on demand. Indeed, the increase in mobile telephony that marked the decade of the 1990s has changed our expectations for person-person communication. On the other hand, the interfaces on mobile phones are very reminiscent of computing in past decades, with textual based keyboard only interaction on small screens with low-quality resolution and color. We are seeing new modes of communication facilitated by old forms of interaction.

Individual exercises

ex.4.1 (open), ex.4.2 (tut), ex.4.3 (tut), ex.4.4 (tut), ex.4.5 (open), ex.4.6 (tut), ex.4.7 (tut)

Worked exercises in book


Discuss the ways in which a full-page word processor is or is not a direct manipulation interface for editing a document using Shneiderman's criteria. What features of a modern word processor break the metaphor of composition with pen (or typewriter) and paper? [page 173]

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exercises: 1. human | 2. computer | 3. interaction | 4. paradigms | 5. design basics | 6. software process | 7. design rules | 8. implementation | 9. evaluation | 10. universal design | 11. user support | 12. cognitive models | 13. socio-organizational | 14. comm and collab | 15. task models | 16. dialogue | 17. system models | 18. rich interaction | 19. groupware | 20. ubicomp, VR, vis | 21. hypertext and WWW