human computer interacon - kth · human‐computer interacon is a discipline ... acceptability: on...
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Human computer interac3on
”Perspec3ves on HCI” Jan Gulliksen
2009‐10‐12
Agenda • Theory base and perspec3ves • Mul3disciplinarity • Defini3ons
– What is HCI? – What is design? – Approaches to UI design – The history of the concept of usability – Users and par3cipa3on – SoNware development methods
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Det enda som intresserar användaren är Gränssnittets
utseende Dynamisk
interaktion i ett arbets- sammanhang
CSCW
Perspec3ves on HCI
HCI
Sociology
Psychology IS
RE
Engineering
SE Ergonomics
Work science
Design
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The computer reaches out – The historical con3nuity of user interface design (Grudin, 1990)
What is HCI? Human‐computer interac3on is a discipline concerned with the design, evalua.on and implementa.on of interac3ve compu3ng systems for human use and with the study of major phenomena surrounding them.
ACM/SIGCHI Curriculum development group (hYp://www1.acm.org/sigs/sigchi/cdg/)
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HCI enligt ACM/SIGCHI cdg
Perspek3v på MDI • Betraktarperspek3v • Ak3onsforskningsperspek3v
• “it may promote our academic careers, but we won’t change the world” (Thimbleby)
• Olika perspek3v innebär också aY de referenser som man bedömer som mest centrala varierar.
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Four major approaches to user interface design
• CraN approach • Cogni3ve engineering • Enhanced soNware engineering • Technologist
(Wallace & Andersson, 1993)
HCI as craN • Building human‐computer interfaces involves applying the relevant knowledge in a complex problem‐solving context to systems of tasks and ar3facts too complex to be completely understood. In prac3ce, the dis3nc3on between design and implementa3on are necessary so blurred that the construc3on of human‐computer interfaces can surely be considered as craN (Wroblewski, 1991)
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HCI as craN • A structured methodology for the development of interfaces is impossible, as the aesthe3cs of interface design do not lend themselves to analy3cal techniques.
• What interface designers need is talent, not methodology.
Design as Cogni3ve Engineering • Cogni3ve metrics methods • Grammar models
• Knowledge methods
• User modelling methods
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Technologist approach to design • UIMS (User Interface Management Systems) • Formal specifica3on methods
• Prototyping
Prototyping • An aYempt to provide a means of dynamic requirements specifica3on and analysis.
• ”Design begins long before the first prototype sees the light of day, unless assistance is provided in the early design phases, automated tools will simply allow bad interfaces to be developed more rapidly.”
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Enhanced soNware engineering • ”The idea of most of these enhanced soNware engineering methods is to supplement the requirements analysis stage with a task analysis technique, which can beYer iden3fy the needs of users and provide informa3on for the specifica3on of the user interface, in a nota3on that is compa3ble with the original methodology and familiar to the analysts.”
How can HCI have any impact on the user interface design?
• ”If HCI wants to make significant impact on the interface design it will have to be packaged in a way that is aYrac3ve to developers and accept the constraints that this imposes.”
(Wallace & Andersson, 1993)
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Talent view • ”Great design comes from great designers”. The role of HCI is simply to ”…empower and liberate the crea3ve mind.” (Brooks, 1987)
• “Interface design is most oNen in the hands of Salieri than Mozart” (Brooks, 1987)
Theory view • Theory‐based design of ar3facts has never occurred on a non‐trivial scale.
• Applied work proceeds successfully without reference to basic science.
(Carroll, 1989)
• Scien3fic knowledge is not prescrip3ve, it is only explanatory and predic3ve.
• Theory has only provided another area where skill is required of the designer.
(Long & Dowell, 1989)
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Method or Process • It is the process or method used to develop interfaces that is the main determinant of interface quality.
(Gould, 1988, Lewis, 1990, Whiteside et al. 1988)
• Process is not a direct subs3tute for talent, but by reducing dependence on talent it can greatly increase the chance of successful design.
Itera3ve design • Success is determined by the nature of feedback applied during an itera3ve process of evalua3on and redesign, not by the quality of the ini3al design.
(Lewis, 1990)
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Criteria for an effec3ve method • Design philosophy • Flexibility • Robustness • Scope • Precision • Mapping • Compa3bility
• Analyst par3cipa3on • User par3cipa3on • Communica3on • Ease of use • Produc3vity • Quality
(Wallace & Andersson, 1993)
Background on soNware process models
• The code‐and‐fix‐model • The stagewise model
• The waterfall model
• The evolu3onary development model
• The transform model
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The spiral model Each cycle of the spiral begins with the iden3fica3on of:
• Objec3ves of the por3on of code • Means of implemen3ng the por3on of the product
• Constraints imposed on the applica3on of alterna3ves
The birth of the concept of Usability
• ”It is not the u3lity, but the useability of a thing that is in ques3on”
(Thomas De Quincey, 1842)
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Typical user responses to inadequate systems
• Disuse • Misuse • Par3al use • Distant use • Task modifica3on • Compensatory user ac3vity • Direct programming • Frustra3on and apathy
(Ramsey & Atwood, 1979 based on Eason, 1974)
Four principle components of any system situa3on
(Shackel, 1984 ‐ The concept of usability)
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U3tlity versus usability
Useful
”Usefulness is the power to sa3sfy human wants” • Fulfils purpose • Func3ons within the range of environments
• Rela3on to costs
U3tlity versus usability Usable
Depends on a) the design of the tool in rela3on to its users and
b) upon the success of the user support provided Judged by
a) subjec3ve assessment of ease of use and
b) objec3ve performance measures of effec3veness in using the tool.
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U3lity versus usability • U.lity is ”the capability in machine func3onal terms to fulfill
the specified range of tasks within the specified range of environmental scenarios” (p. 53)
• Usability is ”the capability in human func3onal terms to be used easily (to a specified level of subjec3ve assessment) and effec3vely (to a specified level of performance) by the specified range of users given specified training and user support to fulfill the specified range of tasks within the specified range of environmental scenarios”. (p. 54‐55)
Usability metrics • Usability = f(task, tool, environment, users) • Usability can only be compared by varying one variable at a 3me.
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The paradigm of usability and related concepts.
U.lity Will it do what is needed func?onally?
+
Usability Will the users actually work it successfully?
+ Likeability Will the users feel it is suitable?
MUST BE BALANCED IN A TRADE‐OFF AGAINST
Cost What are the capital and the running cost; what are the social and organisa?onal consequences?
TO ARRIVE AT A DECISION ABOUT
Acceptability: on balance, the possible alterna?ve for purchase
(Shackel, 1984 ‐ The concept of usability)
ISO 9241 Part 11 Guidance on Usability
Defini3on of Usability
The extent to which a product can be used by specified users to achieve specified goals
with effec.veness, efficiency and sa.sfac.on in a specified context of use.
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Usability engineering ”Engineering in general is directed to building things according to a func3onal specifica3on with needed func3onal capacity, economically and for delivery at a specific 3me.”
”Usability engineering provides a collec3on of techniques to support management of resources in the development of user interfaces and computer func3on.”
(Whiteside, BenneG & HolzblaG, 1988 ‐ Usability Engineering)
Usability aYributes specifica3on
Attri-bute
Mea-suring concept
Mea-suring method
Worst case
Planned level
Best case
Now level
Install-ability
Instal-lation task
Time to install
1 day with media
1 hour without media
10 min. with media
Many can’t install
(Whiteside, BenneG & HolzblaG, 1988 ‐ Usability Engineering)
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Why understanding users is so difficult?
(Norman, 1986 ‐ Cogni?ve engineering)
The human being as an informa3on processor
Nivå av kognitivtmedvetande Automati seri ng i nnebär successiv
transformation av arbetet til l att utföras på enlägre kogniti v medvetandenivå.
E n hög medvetandenivå,enkanalig
E n hög nivå av kogni ti vt medvetande, storkapacitet för paral lel la processer
Kapacitet
There are different levels of cognitive awareness. On a high level of cognitive awareness, the human being is single Processing, but successive repetition of a task can automatise it down to a lower level of cognitive awareness through automatisation.
(Nygren, 1992 ‐ The art of the obvious)
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Program development as a social ac3vity
• Communica3on is central • User/Profession oriented languages • Program development as a social ac3vity
• The philosophical basis for research on system development
(Nygaard, 1986 ‐ Program development as a social ac?vity)
Deltagande design
• Användare och utvecklare deltar på lika villkor • Användare deltar som kompetenta prak3kanter • Designers måste ta arbetsuppgiNen på allvar
• SyNet är aY höja arbetsplatsens kunskap • Datorerna är verktyg som används för aY åstadkomma en
arbetsuppgiN
• Kvalitet är minst lika vik3gt som produk3vitet • Konflikwylld process • Arbete är i grunden en social process
(Greenbaum & Kyng, 1991 ‐ Design at work)
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Deltagande designprocessen • Baseras på användarnas arbetsru3ner • Ömsesidigt lärande • Bekanta utvecklingsverktyg, mock‐ups snarare än formella
språk
• Åskådliggör den fram3da arbetssitua3onen genom experiment med prototyper i verkliga arbetsmiljöer
• Fokuserar minst lika mycket på organisa3onen som på tekniken
(Greenbaum & Kyng, 1991 ‐ Design at work)
Exempel: UTOPIA
• In3mt samarbete med fackföreningarna
• Mock‐ups; Kartongdatorer, diaprojektorer, etc. • Modellering genom s.k. Tapet‐sessioner • Organisatoriska verktygslådan • Seriösa spel • ”Opera3onen lyckades, men pa3enten dog”
(Greenbaum & Kyng, 1991 ‐ Design at work)
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User par3cipa3on in different development contexts
Vad påverkar uwormningen av eY gränssniY?
Standarder
Style Guide
Generella
designregler Designerns
Kompetens/förmåga krea3vitet
Datorer
Nätverk
Utvecklings‐verktyg
Bildskärmar
Upplösning/Prestanda
Användarna
Kunskaper
Erfarenheter
Arbetssitua3onerna
Verksamheten
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Defini3ons of design “Finna räY fysisk komponent 3ll en fysisk struktur.”
“En målinriktad problemlösningsak3vitet”
“Simulera vad vi vill göra innan vi gör det 3llräckligt många gånger för
aY bli 3llfreds med resultatet”
“Det tänkta språnget från dagens faktum 3ll fram3dens möjligheter”
“a crea3ve ac3vity that involves bringing into being something new
and useful that has not existed previously” [Jones, 1981].
Industrial design • “The arrangement of formal elements to a whole, considering
technical, ergonomic, economical, social, aesthe3c and other factors, mainly in mass‐produced products (but also environments or services) with a specific func3on given in advance” [Monö,
1974].
• “Design concerns itself with the meanings artefacts can acquire by
their users” [Krippendorff, 1995].
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Engineering design “Användandet av vetenskapliga principer, teknisk informa.on och fantasi i defini3onen av en mekanisk struktur, maskin eller system som har 3ll uppgiN aY uwöra en fördefinierad funk3on med maximal effek.vitet och funk.onalitet.”
(Preece et al., 1994 ‐ Human Computer Interac?on)
”The Psychology of Everyday Things” – D.A. Norman
“An ordinary user can have problems using a swing door, turn on an automa3c faucet or programming his/her VCR. In most situa3ons the designer aimed for beauty, not u3lity...
He probably won a design prize…”
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”Design Methods” – J.C. Jones “Is designing an art, a science or a form of mathema3cs?
The main point of difference is that of 3ming. Ar3sts and scien3sts operate on the physical world as it exists at present, mathema3cians operate on abstract rela3onships that are independent of historical 3me. Designers are bound to treat as real that which exists only in an imagined future and specify ways in which the foreseen thing can be made to exist.”