Human-Computer

Interaction

CA357

Lecture 7

More on Prototyping

3

Overview

• By the end of the session, you should be aware of:

– Design

– Importance of prototyping

– Low fidelity vs High fidelity prototyping

• Why are we doing this?

– Prototyping is useful for developing any system

– VB gives you an additional skill for your CV

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What is a prototype?

• To construct a version of a system that may be

– Functionally incomplete

– Does not cover the whole system

– Lacks the performance of the final system.

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What is a prototype?

• A storyboard, i.e. a cartoon-like series of scene

sketches

• A Powerpoint slide show

• A cardboard mock-up

• A piece of software with limited functionality written

in the target language or in another language

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Why do we prototype?

• To test out technical feasibility of design ideas

• To clarify vague requirements

• For initial user testing and evaluation

• Checks that a design direction is compatible with the

rest of the system development

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Why do we prototype?

• Support designers by choosing between alternative

designs

• Stakeholders can interact with a prototype more easily

than viewing a document or drawing

• Enables team members to discuss ideas for

improvement

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What do we prototype?

• Screen layouts and information display

• Work flow, task design

• Difficult, controversial, critical areas

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What do we prototype?

• Fidelity refers to level of detail

• Low-fidelity vs high-fidelity

• We can iterate the prototype until it meets the

needs and requirements of the user

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Low fidelity prototyping

• “Quick and dirty”

• Uses a medium which is unlike the final medium, e.g.

paper, cardboard

• E.g. Cardboard cutouts, Post-it notes, Storyboards

• Used for exploring design ideas

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Low fidelity examples

• Sketches

– Drawing of the outward appearance of the

intended system

– Often concentrate on high level concepts

– Difficult to envision progression between screens

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Low fidelity examples

• Storyboards

– Graphical depiction of outward appearance of intended system

– May show showing how a user might progress through a task

using the device

– Can be used with a scenario

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Low fidelity examples

• Storyboards

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Low fidelity examples

• Wizard of Oz

– The user thinks they are interacting with a computer, but a

developer is responding to output rather than the system.

– Usually done early in design to understand users’ expectations

Why might this approach not be appropriate?

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Question

• What are the benefits and weaknesses of low

fidelity prototyping?

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High fidelity prototyping

• Uses materials similar to the final product

• Prototype looks more like the final system

• E.g. Macromedia Director, Visual Basic, C++

• Used for purposes of exploration and testing

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High fidelity example

• Interface Builder

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Question

• What are the benefits and weaknesses of high

fidelity prototyping?

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Compromises

• Vertical prototyping

– Limited features

– Narrow system with lots of functionality

– Can only test limited part of the system

• Horizontal prototyping

– Surface layer designed

– Limited underlying functionality

– Can test appearance

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Three main types of prototype

• Throw-Away

• Incremental

• Evolutionary

• Final product must then be engineered and evaluated

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Evolutionary prototype

• From a storyboard

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Evolutionary prototype

• To a high-fidelity version

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Evolutionary prototype

• To a high-fidelity version

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Summary

• Prototypes answer questions, so prototype appropriately

• Low fidelity prototypes are more suitable for exploration

• High fidelity prototypes are more suitable for learning

• Iterate and use prototypes for choosing between alternatives

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References

• Preece, J., Rodgers, H. and Sharp, Y. (2007) Interaction design: Beyond human-computer interaction. (2nd Edition) Chapter 11.

• For next time, please read:

– Sharp et al. Chapter 15