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Chapter 4 : Descriptive Chapter 4 : Descriptive ApproachesApproaches

““What workers really doWhat workers really do””

Chapter 4 : Descriptive Chapter 4 : Descriptive ApproachesApproaches

““What workers really doWhat workers really do””

홍 승 권 홍 승 권

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Contents

1. Purpose2. Descriptive approaches: Current

practice3. Why descriptive approaches are not

enough?4. Existing techniques for getting around

the task-artifact cycle5. An alternative way of getting around

the task-artifact cycle

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Purpose

Using Four cases– To illustrate the important contributions of

descriptive approaches– To identify additional dimensions that must be

considered in work analysis Descriptive approach

– One of possible means to investigate intrinsic work constraint, rather than an end itself

Computer-based information systems should not be designed based solely on studies of currents. → Formative Approach

Scope of descriptive approachesDescriptive WA is accomplished by conducting

field studies that– document the practical challenges that workers actually

face on the job– and the practices that workers have developed to cope

with those challengesEurope VS America

– 30 years tradition in EuropeTask VS Activity

– Task : Official actions that are prescribed to workers. (Normative approach)

– Activity : Informal actions that workers actually perform in practice (Descriptive Approach)

There are many different perspectives in descriptive approaches → 4 categories– A case study from situated action– A case study from naturalistic decision making– A case study from activity theory– A case study from distributed cognition

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A case study from situated action

Suchman (1987)– Anthropologist– 두 명의 사무직원이 phototype 지원시스템을

사용하면서 photocopying machine 를 조작할 때 어떻게 협업하고 interact 하는지 조사

– Conversation 분석• 사람들 사이의 대화는 기계와 사람 사이의 대화를 이해하는

초석 Theoretical Foil

– Artificial intelligence approach to planning– The same perspective to the instruction based

approach

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Suchman(1987) 의 결과An instruction-based approach is constrained

by limitation on the designers’ ability to predict any users’ action– 작업자들은 지원시스템과 복사기에 나타나는 메시지에 대한

그럴듯한 다른 해석을 했다 . – 더구나 작업자들은 지원시스템에서 고려하지 못한 상황을

직면하게 되었다 . Suchman said that purposeful actions are

inevitably “situated actions” – Situated actions are responding to “local interactions

contingent on the actor’s particular circumstances결론 : Actual behavior is far from the rational

ideal

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A case study from naturalistic decision making

Klein(1989)– Experimental Psychologist– 시간압박과 책임감 하에서 소방업무를 수행하는 소방

지휘관의 의사결정과정에 대한 조사– Retrospective naturalistic studies

• 평균 23 년의 유 경험자들에게 중요하고 일상적이지 않은 사건들을 서술하도록 요청

Theoretical Foil– Classical decision making : To follow a thorough and

rational approach– 여러 개 평가척도설정 , 각 척도의 가중치 산정 , 대안들 비교

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Klein(1989) 의 결과그들의 경험에 따라 상황을 판단하고 행동을 결정Why experts “go with the flow”

– 분석적이고 규정에 의해 일련의 행위를 선정할 수 있는 시간이 없음 : Too laborious mental deliberations.

• Not to find optimal action, but to find satisfactory action (feasible, timely and cost-effective)

– 경험자이고 전문가이기 때문에 , 환경 속에 informative cues 를 인지할 수 있는 지각능력이 있으며 . Action 의 선택도 경험에 의해 선택

• 환경 속에 informative cues 를 인지할 수 있고 , 이 Cue들에 의해 특정상황을 효과적이고 선택적으로 인지할 수 있다 . 이것은 그들에게 친밀한 분류 방법이다 .

• 상황을 인지할 수 있기 때문에 , 그들은 과거의 경험에 비추어 적절한 action 이 무엇인지 안다 .

– 경험의 의존하기 때문에 종종 그들이 인지한 첫번째 대안이 행동 가능한 action 이 된다 .

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Klein(1989) 의 결과Recognition-Primed Decision-making

(RPD)– 소방지휘관은 그들의 경험으로 , 효과적이고

시의적절한 방법으로 상황을 인지 (recognize) 할 수 있다 .

– 그리고 situation assessment 를 관련 행동으로 연계 시킨다 .

결론 : Actual decision making is far from the normative approach prescribed by classic decision theory

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A case study from activity theory

Bødker(1991)– Computer scientist– The participatory design of computer–based

systems– UTOPIA Project– 작업자들이 어떻게 목표를 달성하는지를 조사하기 위해

Descriptive task analysis 를 수행하였음 .• 미래장치개발을 위해 요구 스팩 설정 , 프로토타입 개발 및

시험• 각 단계에서 사용자 참여

Theoretical Foil– Anglo-American approach to HCI

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Bødker(1991) 의 결과

She wanted to find a systematic framework Thus, to adopt activity theory originated from

the psychology of Soviet union

Activity theory-based HCI

Anglo-American HCI

Context-based Context-based Little Context-based

Semantic/Syntactic

semantic features of the interface

Syntactic and Lexical features of the interface

Usefulness/Usability

Usefulness (functionality) Usability

Perspective Ecological perspective Cognitive perspective

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Bødker(1991) 의 결과Activity theory could be adapted to the

practical needs of HCI and its concepts provided a good descriptive understanding of the idea collected during UTOPIA

Activity theory is the study of goal-directed activity – Instead of focusing on the device, goal-focus

Goal focus 의 의미1. 도메인의 semantic 에 대한 깊은 이해가 요구됨2. Goal-oriented activity 는 문화 , 사회적 context 내에서

도구를 갖고 수행된다 . 3. Goal-oriented activity 는 사람의 기술과 전문성을

이해해야 하고 , 시스템은 기술과 전문성의 향상을 돕는다 . 4. 종합적으로 , context-conditioned variability

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A case study from distributed cognition

Hutchins (1995)– Anthropologist– Field study of current practice in the domain of ship

navigation– On the navigation bridge of a number of US Navy

ships at sea– To understand the nature of human cognition in

naturalistic settings Theoretical Foil

– Physical symbol system hypothesis (PSSH)– Such as digital computer, human cognition involves

mental information processing driven by well-defined rules and representations stored in human memory.

Hutchins(1995) 의 결과

1. Information processing are not confined to the brain, but are instead distributed spatially across individuals and artifacts and temporally as a function of the history of a particular culture.

2. Workers frequently accomplished task goals, not in isolation through mental information processing, but as a functional team through mutual coordination of their actions

3. Cognition “in the wild” is an emergent activity that is not completely specified ahead of time.

4. Historical influence of cultures were very important. Many useful artifacts and many of the practices were adapted products of navigational experience. → Not a strict mental activity mechanically performed by an individual.

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Comparison of four case studies

사례 분석가의 배경 적용분야 상대 이론 주요 기여

Suchman(1987)

Anthropology

Photocopying

Artificial Intelligence

Situated Action

Klein (1989)

Experimental Psychology

Fire Fighting Classical decision making

RPD Model

Bødker(1991)

Computer Science

Graphic Design

Anglo-American HCI

Activity theory-based HCI

Hutchins(1995)

Anthropology

Ship Navigation

Physical symbol system Hypothesis

Distributed Cognition

참고문헌 : Simonsen and Kensing (1997), Suchman (1995)

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Importance of current practice 4 가지 사례의 차이점

– 다른 배경을 갖은 연구자들에 의해 수행– 다른 적용분야 ( 영역 )– Theoretical foil 이 다름

4 가지 사례의 공통점– It is the enormous value of conducting descriptive studies

of work in representative or naturalistic settings– Converging characterization of human work

• Context-conditioned variability 의 중요성• Human work 는 strong social components 를 갖는다 . • Work is also seldom solely focused on internal mental

processing because worker create tools: reducing the burden on scare cognitive resources.

• Current work practices are shaped by historic cultural factors. • Time pressure and other constraint 하에서 작업을 하지만 , 경험을

통해 업무수행에 필요한 전문지식을 쌓는다 .

Implications for work analysis

Work analysis framework must include at least five dimensions of work

1. Work domain analysis 필요– 친숙하지 않은 사건을 다루기 위해 information requirements

를 식별하기 위해…2. Constraint-based task analysis 필요

– 작업목표를 flexible, situated manner 로 달성하는데 도움을 주는 information requirements 를 식별하기 위해 …

3. Effective Strategies 의 분석 필요– 특정 도메인에서 일어나는 어떤 사건을 다시 일으킬 수 있는

메커니즘을 식별하기 위해…4. Social and organizational factors 를 분석할 필요

– Computer based information system 를 만든다는 것은 새로운 조직구조를 만드는 것 – 각 개인역할 , 팀의 조직 , 구성원간의 교신 등

5. 요구되는 다양한 Workers’ competences( 적성 , 능력 ) 식별– 전문가 행동을 지원하고 , skill acquisition 을 지원하는

정보시스템을 설계하기 위해…

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Why descriptive approaches are notenough: The task-artifact cycle

1. Limitations of basing design solely on current practice

2. Are these limitations recognized?3. From descriptive analysis to design

implications: The track record4. People are adaptive : the task-artifact

cycle5. Summary

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Limitations of basing design solely on current practice

Intrinsic Work Constraints– Constraints on achieving work goals,

independent of any particular device– These constraints are an inherent part of

work in a particular domain– IWC delimit the actions that are required

to get the job done

Current Work Practices– Current practice is device-dependent

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Why computer-based information systems should not be designed to support current practices.

Intrinsic Work Constraints

Current Work Practices

Currently Unexplored Possibilities

Workaround Activities

Functional Actions

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Direction of computer-based information systems design

Currently unexplored actions may require too much time, computational effort, memory demands or knowledge with the existing device.

Then if with the existing information systems, workers may simply decides to omit this tasks

If the requisite computer support were provided, these unexplored possibilities could very well become a productive part of workers’ practices

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Implications Computer-based information systems should ideally

be designed to support intrinsic work constraints, not just current work practices

Two reasons– We do not want to base our design on the workaround

activities that are vestiges of poor device design– We want to support currently unexplored possibilities.

Work analysis 는 현 작업보다는 intrinsic work constraints 를 식별하는 것이다 . 그러나 이것이 descriptive studies 의 무용론을 이야기 하는 것은 아니다 .– The point is that future designs should go beyond

current practice by removing unwanted inefficiencies and by adding new functional possibilities.

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Are these limitations recognized?Limitations of Descriptive Analysis

– Benyon (1992) : “Embodying current practice in future systems is a fundamental error”

– Beyer and Holtzblatt(1998), Holmqvist(1991)

However,– The analysis of current practices should be

viewed as one of several possible means to investigate work constraints, rather than an end in itself

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From descriptive analysis to design implications: The track record

Social science– 현 상황 분석에는 적절하지만 , 새로운 정보

시스템 설계에는 부적절Activity theory

– The descriptive nature of activity theory make it difficult to develop a novel design

Francophone ergonomics communityHuman factors community

People are adaptive : the task-artifact cycle

Task-artifact cycle (Carroll et al. 1991)

– 현재 work practice 를 기준으로 requirements 가 만들어지고 artifact 를 디자인한다 .

– 현장에 배치되면 새로운 work practice 가 만들어진다 .

Requirements Identification

Possibilities for Work Practices

Workers’ Tasks

Design of Artifacts

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People are adaptive : the task-artifact cycle

If we conduct a descriptive work analysis to understand workers’ current tasks, we will identify requirements that could be used to design a new artifact

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Existing techniques for getting around the task-artifact cycle

Rapid prototyping and iterative user testing– To create prototypes of new designs and evaluate

them by having workers use them– The end goal is to iteratively maximize the

overlap between the two sets• The subset of workaround activities becomes

smaller and smaller• The subset of currently unexplored possibilities

becomes smaller and smaller

Scenario-based design (Carroll et al. 1991) – Analytical techniques for trying to achieve the

same objective ↔ Empirical way– Scenarios provide a means for analytically

evaluating “Simulated future work”

Limitations: The problems of device-dependence and incompleteness

Strong device dependence– A dog chases its tail : continuous iteration process

Incompleteness– Scenarios representation is incomplete : the number and range of

tasks– Limitation by the ingenuity and creativity of the designer– EX) Accident data

T1 T2 T3 A3A2 A1

New Possibilities

New Requirements

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An alternative way of getting around the task-artifact cycle : Modeling intrinsic work constraints

Completeness : The need for models

Scenario/Prototype

Modeling

Inductive, bottom-up activities

Top-down basis for generalization

Don’t know what factors are included and what factors are missed

To make explicit what attribute have been included

Representing exemplars Representing classes

Models provides a more systematic and explicit basis for work analysis

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Device-independence : focusing on intrinsic work constraints (1)

Model what?1. There are many different entities

that could be modeled2. To find a way escaping from the

regress by the task-artifact cycle3. To find the set of intrinsic work

constraints ↔ Not including workaround activities

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Device-independence : focusing on intrinsic work constraints (2)

Work analysis methods should not prespecify the follows– Existing set of sensors– Contents and structure of the database– Functionality of the automation– Allocation of functions between computer and

workers– Allocations of job responsibilities– Appearance and structure of the interface– Workers’ competences

Because each issues is a point of design leverage → inheriting the vestiges of the old

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Device-independence : focusing on intrinsic work constraints

The following decisions should be made based on the findings obtained from the work analysis– What information should be gathered– How it should be organized– How to automated– What to automated– How to organize work– How to display information – How to train operators

Ways of identifying intrinsic work constraints– Studying the structure of the work domain :

identify efficient tasks and novel strategies– Analytical model (e.g. Operation research)– Current practice

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Summary What type of work analysis is

appropriate for complex sociotechnical systems?

Normative approaches– Strong limitation

Descriptive approaches– Limitation

1. Task-artifact cycle: inherit the deficiencies of current practice

2. To overcome the cycle, prototyping and scenario method

3. These limitations can be directly addressed by explicitly modeling intrinsic work constraints