Human Computer Interaction

1. Human Computer Interaction • Study and design of user interfaces and interaction • British Computer Society ~“to stress the good design, documentation and usability” • HCI approach – iterative development with focus on user testing at an early stage • HCI is applied engineering with contribution from • Cognitive Psychology • Cognitive Science and Engineering • Computer Science • Ergonomics • Artificial Intelligence • Graphics and Industrial Design • Engineering generally • Sociology, Anthropology and Philosophy

2. Human Computer Interaction • HCI is not about ‘looking good’ or ‘making thing pretty’ – It is about making software work for user • Good HCI does not grow on trees it has to be cultivated • Owning an aeroplane does not make you a pilot • REALITY • Many systems are difficult to use but people are adaptable • There may be conflict between safety and efficiency • Which garage do you prefer – the one which offers you coffee, but does not fix your car, or the one with gruff mechanics who are honest and know their stuff???

3. Human Computer Interaction • Selection and design of devices – screen, keyboard, printer, etc. • Selection and design of interaction styles • Selection and development of tools and methods • Design of the environment where a computer is used • The tasks to be carried out using a computer • Organizational impact of a computer system • The training requirements – initial and continuing • The design of support material, manuals, on-line helps, etc. • The attitudes and expectations of users • Safety issues

4. Human Computer Interaction~ Human Factors Design Issues • The need for consistency • One of the common causes of problems with computer based systems • Dialogue Design • When interacting with a system a dialogue is in progress between the system and the user – this has to be planned, scripted or choreographed • System Feedback • Lack of suitable feedback causes feelings of discomfort and encourages errors, e.g. pressing RETURN too many times until the response is seen

5. Human Computer Interaction~ Human Factors Design Issues • Amount of Feedback • Tendency to squeeze too much on to screen and to show more than is necessary for the current task • Appropriate pacing • Too slow – causes frustration • Too fast – causes pressure to perform

6. Human Computer Interaction~ The Problems • Mismatch between user and computer • Often the user has to adapt to the computer • Terminology that of computer instead of user • Computer function rather than task oriented • Physical limitations • Height • Reach • Eyesight • Sensitivity to lighting condition

7. Human Computer Interaction~ The Problems • Human information processing limitations • Short term memory limitation • Attention highly selective and narrow • Long term memory very unreliable • Recognition easier than recall • Over learning for frequent tasks • Reasoning frequently illogical • Judgements subject to biases • Affected by fatigue and emotion

8. Human Computer Interaction~ The Problem • Resistance to Change • How is change managed? • Who is involved? • Technology is search of a solution • Disruption of existing social order • Building for whom? • Designer build for themselves • Poor understanding of users, tasks, organizations • Poorly specified problems • Poorly realized solutions

9. HCI Issues for Multimedia Design • looking at how issues in HCI, human-factors engineering, user-centered design, can influence multimedia design • use of different media types • MM design for vision, hearing, cognition, memory,attention • MM design guidelines • design issues for static and dynamic media • educational MM

10. Types of Usability • For multimedia, usability has three viewpoints • Functional usability • How easy a product is to use • GUIs, menus, interaction • Information delivery • how well does the product deliver the message • prime concern • “multi media “ • just because you present the material in a different way doesn’t mean that it will be delivered better • Learnt content • how well does someone learn the content delivered by the product • more applicable to educational multimedia but still considered for movie-style presentations

11. Essential Issues of Multimedia • with MM you have more ways to present information • should be more attractive than standard text and still images • however potential for even bigger ‘mess’ • should be about: • delivering information in a novel way • enhancing interaction by different techniques

12. Multimedia ISO Standard Terms • message • the content of communication between a sender and received. • medium • the means by which that content is delivered (how the message is represented rather than the technology). • modality • the way a message is perceived by a person (e.g. vision, hearing, touch). Note that this is not technology based but human attributes.

13. Dynamic Media • •considerations: • how can the media be controlled over time? • can the speed of presentation be change? • what controls exist over the presentation? • how can the media format be changed? • can the image be expanded (zoom) • can the sound be filtered (amplitude, frequency)? • can components of the dynamic media addressable directly or indirectly?

14. What you should remember aboutdynamic media • dynamic media tend to dominate by attracting attention from static media • dynamic media can easily overload human information processing • retention of detail from dynamic media is poor • co-ordination of information presented • must allow user control over dynamic media

15. Static Media • considerations: • how can the display be controlled? • standard GUI controls, eg sliders (too much text for window and therefore need to scroll down) etc • how can the media format be changed? • depends on the storage format eg text changed in size (point), and shape (font,bold) • are sub-components of medium addressable? • idea of clickable maps where certain aspects of the image can have different features

16. What you should bear in mind • visual images tend to dominate over text • images can be scanned quickly (quick look over)whereas reading is more attention demanding,therefore people will be drawn towards the easier of the two media. • many different messages can be extracted from one image. • interpretation of the message in an image depends on the user’s attention and knowledge of contents. • extraction of information from diagrams requires learning the semantics of a symbolic language • memory of image detail is generally poor unless peoples attention has been drawn to specific facts in the image • • reading is a sequential process. • good sentence structure and layout helps reading • memory for detail in text generally better that for image, although only the higher order structure will be recalled accurately

17. Implications of the eye on MM design • do not expect people to attend to detail in several different areas of an image at once. • People will scan around the image, briefly focusing on different objects, but only one at a time. • in MM systems only one image should be presented at once. • Users can not attend to still images and video at the same time. • movement is a highly effective means of alerting the peripheral vision and drawing the user’s attention. • thus change or movement should be limited to one image, otherwise it will cause stress (due to an inability to attend to both images)

18. Implications of hearing on MM design • only part of the auditory range is necessary for speech. • People tolerate poor sound unless the quality is vital • background noise should be reduced for effective communication • although the human ear is good as suppressing noise, we get distracted • sound is very effective as a means of alerting and warning. • sound is a broadcast medium • speech is interpreted by the rules of grammar

19. Implications of memory on MM • minimise distraction during tasks and memorisation • beware of overloading working memory, both in terms of quantity of information and time span of retention • input from dynamic media rapidly exceeds the capacity of working memory and hence only the high level gist will be retained. • working memory has to be refreshed keeping the information available in persistent media, thus allow to re-view test or image • structuring information (chunking) • memorisation of detail from image is limited

20. Implications of attention to MM • do not use too many competing demands for attention • Attention tends to be diverted by change hence temporal media such as film, animation and sound will dominate over static media such as pictures and text • dynamic media contains change by definition and therefore attract attention more strongly than static • change in static media (highlighting) will attract attention • two or more dynamic media will compete for the users attention and this can lead to stress and fatigue