Lecture 22 Chapter 12 - Human-Computer Interaction

1. Lecture 22Chapter 12 - Human-Computer Interaction

2. A key design activity is to design the user interface • Human-computer interaction (HCI) - the study of end users and their interaction with computers • For every input and output the developer must consider the interaction between the user and the computer • Because the interaction is much like a dialog between the user and the computer, user-interface design is often referred to as dialog design • The field of human computer interaction investigates how people use computer systems, so that better systems can be designed • One aspect is concerned with technological innovation (e.g. better input devices, like electronic pen etc.) • The other aspect is concerned with the human element (e.g. how people reason, solve problems and interact with computers) – the most challenging aspect of HCI!

3. The User Interface • Many people think of the user interface as a component added to the system near the end of the development process • This view is changing as user interfaces become more important and systems become more interactive • To the end user, the user interface is the system • The user interface is everything the end user comes into contact with while using the system – physically, perceptually, and conceptually • Therefore, consideration of the user interface should come early in the development process

5. Physical Aspects of the User Interface • Physical aspects of the user interface include the devices the user actually touches, including the keyboard, mouse, touch screen, keypad • Other physical parts include reference manuals, printed documents, data-entry forms, etc. that the end user works with completing tasks at a computer • The desk space, the lighting, and the terminal hardware also make up the physical interface for the end user

6. Perceptual Aspects of the User Interface • Perceptual aspects of the user interface include everything the end user sees, hears, or touches (beyond the physical devices) • This includes • All the data and instructions displayed on the screen, including shapes, lines, numbers and words, sounds (like beeps etc.) • Recently, computer-generated speech is another aspect • The user “touches” objects such as menus, dialog boxes, and buttons on the screen using a mouse • The user touches objects such as documents, drawings, or records of transactions

7. Conceptual Aspects of the User Interface • Conceptual aspects of the user interface include everything the user knows about using the system including the problem domain “things” in the system the user is manipulating, the operations that can be performed and the procedures followed • To use the system, the end user must know all these details • User’s model (of the system) • What the user knows about using the system, including the problem domain”things” the user is manipulating, the operations that can be performed and the procedures followed when carrying out tasks

8. Designer’s model (of the system) • How the designer sees and understands the system • Problems with user interfaces can be considered as resulting from “mismatches” between the user’s model of the system and the designer’s model • Leads to attempt to study how user’s view systems and how designer’s view systems – can be a big gap!

9. User’s Model (continued) • Much of the user’s model is a logical model of the system • A logical model can be detailed so a user must know quite a few details to operate the system • A user’s knowledge of the requirements for the system becomes the determinant of what the system is, and if the user’s knowledge of the system is part of the interface, then the user interface must be much more than something added at the end

10. User-Centered Design • A collection of techniques that place the user at the center of the development process • Treat users as “consultants” in the design process • Three important principles • Focus early on the users and their work • Evaluate designs to ensure usability • Use iterative development • Note that in user-centered design design and evaluation (testing of the design with end users) are considered together • Iterate and evaluate until a satisfactory result is obtained (from the perspective of the end user)

11. Notes on User-Centered Design • The early focus on users and their work is consistent with the approach to systems analysis which emphasizes the importance of understanding and identifying the system users and their requirements • In contrast, the traditional approach focuses more on the requirements from the business point of view – what needs to be done from a processing perspective rather than a user perspective • The object-oriented approach focuses more on users and their work • With focus on use cases, actors, scenarios etc. • Tend to be more interactive systems

12. Notes on User-Centered Design (cont.) • As discussed in ch. 7 the automation boundary between the user and computer is defined early • User-centered design goes much further in attempting to understand users • What do they know? • How do they prefer to work? • What motivates them? • Very important questions when trying to add technology to complex areas, eg. Health care information systems

13. Principles of User-Centered Design Continued • Second principle of user-centered design • To evaluate designs to ensure usability • Usability refers to the degree to which a system is easy to learn and use • Ensuring usability is not easy • There are many different types of users with different preferences and skills to accommodate to • If the system is too flexible, some users may feel lost • If the system is too rigid some users will be frustrated • Usability engineering • Principled methods for ensuring usability • Involves continual testing of prototypes with end users – e.g. video analysis of end user interactions • A very hot area currently

14. Design and Evaluation Considered Together • In past, traditionally considered as separate topics. In recent years it is becoming recognized that interactive systems require iterative design • Promising approach for design of many systems (and user interfaces in particular) • Iterate and evaluate until a satisfactory result is obtained • Design principles can assist but do not help structure the process of design • Need new design methodologies • Rapid prototyping • User-centered design • Use of methods that go beyond to include continual usability testing with representative users doing representative tasks

15. Usability continued • Usability – ease of use and learning • These concepts are often in conflict • An interface that is easy to learn is not always easy to use • Eg. Menu-based applications with multiple forms and dialog boxes etc. are easy to learn • Easy to learn interfaces are appropriate for systems used infrequently • But if system used all day by office-workers important to make interface fast and flexible with shortcuts, hot keys and information-intensive screens (may be harder to learn but easier to use once learned)

16. Testing for Usability • Developers use many techniques to evaluate interface designs to ensure usability • Some methods • Formal surveys • Focus group meetings • Design walkthroughs • Paper and pencil evaluations • Expert evaluations • Formal laboratory experiments • Informal observation • Some methods allow collection of objective data that can be analyzed statistically

17. Example – video-based usability testing • Method I’m using – video record subjects (representative users of systems, e.g. doctors, nurses) as they interact with a system and “think-aloud” • Record all screens on video • Can code the video to identify problems users have and suggestions for improvement • Can statistically compare alternative designs • Can provide feedback to designers to improve design

18. Usability continued • Third principle of user-centered design • Use iterative development – doing some analysis, then some design then some implementation (and repeat) • cycling through with some analysis (evaluation of the design) then some feedback to designers and improvements, followed by further evaluation etc. • After each iteration the project team evaluates the work on the system and makes changes if needed • Iterative development keeps the focus on the user by continually refining the system after each iteration

19. Human-Computer Interaction as a Field of Study • User-interface design techniques and HCI as a field of study evolved from studies of human interaction with machines in general – human factors engineering or ergonomics • Formal study of human factors began in World War II, when aerospace engineers studied the effects of arranging controls in cockpit • What the pilot does is the “human factor” that engineers realized was beyond their control

20. Example of the importance of the human factor involving a minor change • Designers switched location of the throttle and the release handle for the ejection seat • The result was a dramatic increase in the number of unexplained pilot ejections! • When under pressure, the pilots grabbed what they thought was the throttle and ejected from the plane • Designers dismissed the problem as need for better traning • But problem continued! • Became apparent that the key to the “human factor” was to change the machine to accommodate the human rather then trying to change the human to accommodate the machine • Computer example in avionics – early Airbus accidents • Too much control taken over by the computer system

21. Emergence of the field of Human-Computer Interaction • The field of human factors was associated with engineering, since engineers designed machines • But engineers often found human factors frustrating (different personality types) • Gradually specialists emerged who drew on many disciplines to understand people and their behavior • Disciplines drawn on for HCI • Cognitive psychology • Computer science • Social psychology • Linguistics • Sociology • anthropology

23. Example – Impact of HCI work from Xerox PARC on computers • In the 1970’s an important contribution to the field of HCI began at Xerox Corporation • Xerox produced high-speed photocopy machines with ever increasing options • Recognized the importance of making these machines easy to use and learn • Xerox hired people with many backgrounds – e.g. computers, psychology, anthropology etc. • Xerox started the Xerox Palo Alto Research Centre (Xerox PARC) to study issues that affect how humans operate machines

24. Xerox began offering photocopy machines with • Touch screens • Menu-driven interfaces displaying icons like stacks of paper, staples etc. • Research at Xerox PARC also included work on computers • First object-oriented language, Smalltalk was developed by Alan Kay at PARC • First laser printer • Basis of portable computing worked out at PARC as well • Kay developed a portable personal computing platform (Dynabook) • Key aspects of GUI (graphical user interfaces) also worked out at Xerox PARC

25. In late 70’s Xerox developed the first general-purpose personal computer with a graphical user interface – the Xerox Star • Although it was ahead of its time and too expensive it is a landmark in computing • Key features of it were exploited in the early 1980’s by Apple Computers (which was located physically next to Xerox PARC in Silicon Valley) • The features from the Star became part of the Apple Lisa, which led to the Apple Macintosh • The story doesn’t end there! – the Microsoft Windows graphical user interface essentially evolved from the Apple Macintosh interface (initially was a legal battle between Apple and Microsoft over the rights)

26. Field of Human-Computer Interaction (HCI) • The field of HCI has evolved • Academic programs in it (through Computer Science and Psychology programs and departments) • Undergraduate and graduate programs • Major conferences, journals and books • In industry it is beginning to have a major impact • Usability laboratories • Eg. Hewlitt-Packard, Microsoft, Apple, American Airlines etc. • Hire multidisciplinary staff • Computer scientists • Psychologists • Graphics designers • Ethnographers

27. Metaphors for Human-Computer Interaction • The term metaphor describes the overall “concept” you may use to organize all the objects and actions in an interface into a coherent whole • Three major metaphors, or analogies in HCI • Direct manipulation metaphor • Desktop metaphor • Document metaphor • Direct manipulation metaphor • A metaphor of HCI in which the user interacts directly with objects on the display screen • Objects are made visible so the user can point at them and manipulate them with the mouse or arrow keys • Earliest direct manipulation interfaces were word processors that let users type in words directly into a document – in a spreadsheet (which on the screen was conceptually similar to a paper spreadsheet)

28. Direct Manipulation Metaphor (cont.) • Early direct manipulation applications that run using DOS (e.g. spreadsheets, word processors) led to popularity of personal computers • Smalltalk language developed at Xerox PARC extended direct manipulation to all objects on the screen • Buttons • Check boxes • Scroll bars • Slider controls • New icons appeared – eg. Trash cans, which allowed you to directly manipulate an object – put it in the trash

29. Desktop Metaphor • Direct manipulation coupled with object-oriented programming eventually evolved into the desktop metaphor • The display screen includes an arrangement of common desktop objects • Notepad, a calendar, a calculator, file folders containing documents • Newer ones also include a telephone, an answering machine, a CD player • Interacting with these objects is similar to interacting with real-world objects they represent