Interactive Systems Design & Evaluation

• John Burns • e-mail [email protected]

• W 5.6

Recommended Text: HCI, J Preece et al, Addison Wesley, 2001 Also: HCI, Dix, Finlay, Abowd & Beale, Prentice Hall, 1998 Designing the User Interface, B Shneiderman, Addison Wesley, 1998 Newman & Lamming Interactive Systems Design 1995 Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Objectives of this Lecture

• To outline what we mean by ID • To define HCI • To demonstrate the need for ISDE • To indicate the scope of ISDE • To consider some general principles of HCI design • To place ISDE in the context of SD models Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

What is ISDE about?

• Interactive systems are designed to enable communication between the system and the user • This takes place via the systems ‘user interface’ • ISDE is concerned with: – Designing interactive systems to support human activities – Applying usability engineering techniques to evaluate the effectiveness and appropriateness of the design Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Some definitions

• Human-Computer Interaction – a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of the major phenomena surrounding them • User Interface – any boundary between the human user and the computer system (includes documentation and training material) – not restricted to screens, keyboards and mice Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

What is HCI

• HCI is concerned about : – Finding out how people use computers – Trying to ensure that systems are designed to closely match users’ needs – Ensuring that users can make sense of the information that is presented to them – Ensuring that the user can communicate/interact with the system • This is not always the case!!

Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Getting it wrong!

• Some examples of bad design – The ATM – The Car Park Ticket Machine – The Hi - Tec Shopping Trolley – The Photocopier Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Getting it right!

• These illustrate 3 key factors that the designer needs to focus on – The user – The task – The environment • Next slide shows other factors Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Organisational Factors Environmental Factors Health and Safety Factors Interactive Design Sept 03 John T Burns The User Comfort Factors User Interface Task Factors Constraints System Functionality Productivity Factors © Copyright De Montfort University 2003 All Rights Reserved

Justifying HCI

• Poor interface design can lead to – Increased errors – User frustration – Poor system performance – User rejection Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Justifying HCI

• Good Interface design will provide – Fail-safe systems – Competitive advantages – Financial rewards – Increased efficiency – User satisfaction and enjoyment Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

What makes for a good interface?

• A good interface will – Provide feedback – Provide easy reversal of actions (relieves anxiety) – Give users feeling that they are in control – Reduce reliance on STM Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Think about a car...

• how much knowledge about a car do you need to be able to drive it?

• do the best designed cars give the driver the most information about the engine, suspension, etc?

• good design of the interface to the car includes designing controls that are – obvious to use – behave in the way you expect – give fast feedback – are comfortable to use – hide unnecessary information from the user Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Visibility, mapping and affordance

• visibility: the correct parts must be visible, they must convey the correct message - that message is conveyed by signals • mapping: the relationship between what you want to do and what appears to be possible - good design exploits natural and easily perceived mappings • visibility indicates the mapping between the intended action and the actual operation • affordance: the perceived and actual properties of a thing, primarily those fundamental properties that determine just how the thing could possibly be used Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Perspectives on design

• users are often not interested in the program and use it only as a tool to achieve some task in their work – give me £20 from my current account (ATM) – draw me a section of the valve called P1023 in a place I can define (CAD system) – (games are an exception..) • manufacturers are aware of the importance of usability...

• ... but often do not know how to design for usability and how to test or evaluate it effectively Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Continued perspectives...

• think ‘design first, implementation second’ • design the interface first for usability, only compromise in the design for ease of implementation later if necessary • think how the system and interface should support what the user wants to do, rather than what the system is capable of doing Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Misconceptions about user interface design

• a usable system has lots of functions • ‘I know it’s a bit hard to use but it’s all described in the Help system’ • ‘I know it works - I’ve got the people in the office (or on the course) to use it’ Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

User Centred Design

• all systems need not be designed to suit everyone...

• .... but should be designed around the needs and capabilities of those people who will use them usability - concerned with making systems easy to learn, easy to use and efficient to use Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Implications for the design process

• there must be an early focus on users and tasks • there must be a clear understanding of what particular usability attributes are important • to ensure usability targets can be met, there must be testing of prototypes of the design from an early stage in the process • results from prototype testing need to be used to modify the design and this is then retested - i.e. there are iterations in the design - test cycle • software tools are needed to support this process - to enable designs to be built and modified with little programming overhead Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Waterfall model of S/W development requirements analysis & definition System and software design implementation and unit testing integration and system testing operation & maintenance • certainly better than no model at all, but too rigid • requirements change during design process • testing occurs late in the process Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Prototyping Model of S/W development requirements definition quick design build prototype evaluate and refine requirements engineer product Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Prototyping Model of S/W development Advantages • evaluation at an early stage • prototype can be used to explore further requirements Disadvantages • quick design may be badly founded • building prototypes may not necessarily be rapid Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

The Star Life Cycle

Implementation Prototyping Evaluation Task Analysis/ Functional Analysis Requirements Specification Conceptual design/ Formal design • evaluation relevant to all stages in life cycle • intended to be equally supportive of top-down and bottom up development Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Design Methods • There is no single ‘golden’ design method that can ensure successful interactive design • Requires designer to gain an understanding of the problem and apply appropriate techniques • Fundamental to achieving success is the need to shift continually between two types of design activity Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Design Activities • Analysis – During analysis we test the design to ensure it is meeting our targets for usability and quality • Synthesis – Here we shape the design drawing on fresh ideas, previous experience and solutions to similar problems Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved

Further Reading • Chapters 1 & 2 Preece • The Psychology of Everyday things. Norman D 1988 • Turn Signals are the Facial expressions of Automobiles. Norman 1992. – Both books provide amusing and thought provoking examples of bad designs in everyday life. He uses this as the basis to argue for the need for technology to be humanized.

Interactive Design Sept 03 John T Burns © Copyright De Montfort University 2003 All Rights Reserved