Chapter+Two

=Chapter 2=

__2.1 Introduction__ __2.2 People__ __2.3 Activities__ __2.4 Contexts__ __2.5 Technologies__ __2.6 Scoping a problem with PACT__ __2.7 The process of human-centred interactive systems design__
 * Technologies are used to support a wide range of people undertaking various activities in different contexts
 * If technology changes then the nature of the activity will change also. Fig 2-1 (pg.30)
 * Physical differences:
 * Height and weight
 * Different personalities, cognitive skills and preferences.
 * Variability in the five senses (sight, hearing, touch, smell and taste) has effect on accessibility and enjoyment levels of technology for different people in different contexts.
 * ex. color blindness
 * Psychological differences:
 * psychologically, people differ in many ways:
 * people with good spatial ability will find it much easier to find their way around and remember a website than those with poor ability.
 * language differences fit in this category too.
 * attention and memory which are dependent on stress and tiredness.
 * The understanding and knowledge that we possess of something is often called 'mental model'
 * people that do not have good mental models can only perform actions by rote (memorization).
 * Usage differences:
 * Novice and expert users of a technology will typically have very different requirements.
 * Term used for very simple tasks as well as highly complex ones.
 * 10 important characteristics of activities that designers need to consider:
 * 1) something that is undertaken every day (cell phone use) should be designed for easy use whereas something that happens only once a year (changing the battery) can be a bit more complex.
 * 2) time pressures, peaks and troughs of working: designs that work well when things are quiet can be awful when things are busy.
 * 3) Some activities are continuous whereas some are likely to be interrupted; the interrupted tasks should be designed so that finding one's place again is easy.
 * 4) Response time - is instant feedback crucial?
 * 5) Some activities can be carried out alone while some need the coodination and communication with others.
 * 6) well-defined tasks can be accomplished with simple step-by-step instructions; vague activities means that people will have to browse around, see different types of information and then move on.
 * 7) Some activities are safety critical- one mistake could ruin everything.
 * 8) in general it is vital to think about what will happen when a mistake is made and design for such circumstances.
 * 9) data requirement of the activity: large amount of data makes a key board a necessity.
 * 10) the media is just as important as the data: a two-tone display of numeric data demands very different design from a full motion multimedia display.
 * Activities always happen in a context, so there is a need to analyse the two together.
 * Physical Environment:
 * the sun shining on an ATM display may make it unreadable
 * the environment may be noisy, cold, wet or dirty.
 * Social Context:
 * a supportive environment will offer plenty of help for the activity.
 * training manuals, experts to lend a hand.
 * Privacy issues
 * Social norms may dictate the acceptability of certain designs.
 * Organizational Context:
 * changes in technology often alter communication and power structures and may have effects on jobs such as de-skilling.
 * Interactive systems typically consist of hardware and software components and transform some input data into some output data.
 * Input: concerned with how people enter data and instructions into a system securely and safely.
 * Output: output needs to be considered, including the characteristics of different displays.
 * Communication: issues such as bandwidth and speed are critical. So too is feedback to people so that they know what is going on and indeed something is going on.
 * Content: good content is accurate, up-to-date, relevant and well presented.
 * Aim of human-centred interactive system design is to harmonize the PACT elements in a particular domain.
 * PACT analysis is useful for both analysis and design activities
 * to do PACT analysis: designer simply scopes out the variety of Ps, As, Cs and Ts that are possible.
 * For people: designers need to think about the physical, psychological and social differences and how these differences change in different circumstances and over time.
 * For activities: designers need to think about the complexity of the activity, the temporal features, cooperative features, and the nature of the data.
 * Contexts: think about the physical, social and organizational setting.
 * Technologies: they concentrate on input, output, communication and content.
 * Activities in Design:
 * there are many ways of characterizing the activities involved in the design process.
 * David Kelley: design has 3 activities: understand, observe, visualize.
 * Smith and Tabor: 5 activities: understanding, abstracting, structuring, representing, detailing.
 * The book uses 5 activities: requirements, Conceptual design, physical design, prototyping and envisioning, evaluation Figure 2-5 (pg. 40)
 * Requirements:
 * concerned with what the system has to do, what is has to be like, how it fits with other things.
 * functional requirements: what the system should be able to do
 * and nonfunction requirements
 * requirements are generated through discussion with future clients or users of the system, and observations of existing systems and what people do.
 * Conceptual design:
 * designing a system in the abstract, about considering what information and functions are needed for the system to achieve its purpose.
 * deciding what someone will have to know to use the system.
 * Physical Design:
 * concerned with how things are going to work and with detailing the look and feel of the product.
 * structuring interactions into logical sequences and about clarifying and presenting the allocation of function and knowledge between people and devices.
 * Prototyping and envisionment:
 * designs need to be visualized both to help designers clarify their own ideas and to enable people to evaluate them.
 * concerned with finding appropriate media in which to render to design ideas.
 * Evaluation:
 * tightly coupled with envisionment because the nature of the representation used will affect what can be evaluated