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8 Golden Rules of Interface Design 9-3-2012 What is Digital - - PowerPoint PPT Presentation
8 Golden Rules of Interface Design 9-3-2012 What is Digital - - PowerPoint PPT Presentation
8 Golden Rules of Interface Design 9-3-2012 What is Digital Entertainment? It's video games (like SnapShot), short animations (like PaperMan), digital art, and interactivity. So we have created a student club called the Interactive Digital
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8 Golden Rules of Interface Design HW#1 posted, due Wednesday, 9/5/12 Activity#2 due Monday, 9/17/12 Select your project topic
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- Road sign
in Mexico
- Controls on a
rental car
From: www.baddesigns.com
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Usability goals include: Effective to use Efficient to use Safe to use Have good utility Easy to learn Easy to remember how to use User Experience goals include: Satisfying Enjoyable Supportive Aesthetically pleasing Engaging Helpful Motivating
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Visibility Feedback Constraints Mapping Affordance
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Restrict user actions to valid actions Eliminate need for perfect knowledge Recognition over recall
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Poor use of constraints
Tokyo Stock Exchange software did not
prevent trader from making an outrageous trade
Command line systems force you to
remember spelling and syntax of commands
Good use of constraints
Click on icons to invoke commands Gray out unavailable actions
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Visibility Feedback Constraints Map appin ing Affordance
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Na Natural ural mapping ppings: s: no expl planation anations s needed eded
User intentions Available actions Perceived system state Actual system state
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Relationship between controls and their movements and the results in the world Why is this a poor mapping of control buttons?
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Why is this a better mapping? The control buttons are mapped better onto the sequence of actions of fast rewind, rewind, play and fast forward
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Which controls go with which burners?
A B C D
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Us User r in intent ntions ions to av availa ilable ble act ctio ions
Is there a natural mapping between what
users want to do and what appears possible?
Do users stare at technology for sometime
before they take action?
Or do they immediately know what to do? Simplicity can help
User intentions Available actions Perceived system state Actual system state
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Us User r in intent ntions ions to av availa ilable ble act ctio ions
Poor mapping
- Stove top controls
- Clustered light switches
Good mapping
- Consistent play, rewind, fast forward, stop
controls on media devices
- Clearly visible and labeled power buttons
User intentions Available actions Perceived system state Actual system state
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Avail ilab able le actio ions ns to p perceiv ived ed syst stem em state
The user should not be surprised with what
happened after they completed an action
Technologies should behave in expected ways Quick feedback is very important Problems more likely if the mappings
between user intentions and available actions were not good
User intentions Available actions Perceived system state Actual system state
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Avail ilab able le actio ions ns to p perceiv ived ed syst stem em state
Poor mapping
- Pull from a door knob when you were supposed
to push
- Try to close an application that won’t close
Good mapping
- Press gas pedal, feel car accelerate
User intentions Available actions Perceived system state Actual system state
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Perceiv ived ed syst stem em state te to a actual al syst stem em state Users think the technology is doing one thing when it really is doing something else Users unlikely to quickly detect problems
User intentions Available actions Perceived system state Actual system state
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Perc rceiv ived ed syst stem em state te to ac actual al syst stem em state
Poor mapping
- 757 Flight Management System had pilots thinking
they were traveling towards different beacon
Good mapping
- Well-implemented progress bars
User intentions Available actions Perceived system state Actual system state
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Act ctual l system tem state e to us user r in intentio ntions ns Does the system allow states that users would never want? Difficult to implement Important for critical systems
User intentions Available actions Perceived system state Actual system state
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Act ctual l system tem state e to us user r in intentio ntions ns
Poor mapping
- Tokyo Stock Exchange software sold stocks far
below market price (and more than were available)
Good mapping
- Voting systems that allow you to select only one
candidate for President
User intentions Available actions Perceived system state Actual system state
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Visibility Feedback Constraints Mapping Af Affo fordance rdance
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Refers to an attribute of an object that allows people to know how to use it
e.g. a mouse button invites pushing, a door
handle affords pulling
Norman (1988) used the term to discuss the design of everyday objects Since has been much popularised in interaction design to discuss how to design interface
- bjects
e.g. scrollbars to afford moving up and down,
icons to afford clicking on
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Poor affordances
e.g. Doors
Push or Pull? Where to push?
Good affordances
Buttons that
appear clickable
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Interfaces are virtual and do not have affordances like physical objects Norman argues it does not make sense to talk about interfaces in terms of ‘real’ affordances Instead interfaces are better conceptualised as ‘perceived’ affordances
Learned conventions of arbitrary mappings
between action and effect at the interface
Some mappings are better than others
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Perceived or actual properties of objects
What can you do with it? Should you click it, drag it, is it part of the
background?
Can you tell what parts of a user interface are
interactive?
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Virtu rtual al afforda
- rdances
ces How do the following screen objects afford? What if you were a novice user? Would you know what to do with them?
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Concept How to Use Usability Goals determining assessment criteria User Experience Goals identifying important aspects of the experience Usability Principles assessing the acceptability of an interface
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Sh Shneide iderman rman, , Chapt pter er 2, Se Sectio ion n 2.3.4:
- 1. Strive for consistency
- 2. Cater to universal usability
- 3. Offer informative feedback
- 4. Design dialogs to yield closure
- 5. Prevent errors
- 6. Permit easy reversal of actions
- 7. Support internal locus of control
- 8. Reduce short term memory load
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Consistent sequences of actions should be required in similar situations Identical terminology should be used in prompts, menus, and help screens Consistent color, layout, capitalization, fonts, etc. should be employed throughout Exceptions, such as required confirmation
- f the delete command, should be
comprehensible and limited in number
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Recognize the needs of diverse users and design for plasticity, facilitating transformation of content. Novice-expert differences, age ranges, disabilities, and technology diversity affect the requirements that guide design.
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For every user action, there should be system feedback. For frequent and minor actions, the response can be modest For infrequent and major actions, the response should be more substantial
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Sequences of actions should be organized into groups with a beginning, middle, and end. Informative feedback at the completion of a group of actions gives operators a sense of accomplishment (and relief), and a signal to prepare for the next group of actions
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As much as possible, design the system so that users cannot make serious errors. For example, gray out inappropriate menu items, do not allow alphabetic data in a numeric field If a user makes an error, the interface should detect the error and offer simple, constructive, and specific instructions for recovery Erroneous actions should leave the system state unchanged, or the interface should give instructions about restoring the state Make error messages specific, positive in tone, and constructive
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As much as possible, actions should be
- reversible. This feature relieves anxiety,
since the user knows that errors can be undone, thus encouraging exploration of unfamiliar options. The units of reversability may be a single action, a data-entry task, or a complete group of actions, such as entry of a name and address block
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Experienced operators strongly desire the sense that they are in charge of the interface and that the interface responds to their actions. Surprising interface actions, tedious sequences of data entries, inability to obtain or difficulty in obtaining necessary information, and inability to produce the desired action all build anxiety and dissatisfaction.
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The rule of thumb for short-term memory is “seven plus or minus two chunks” The limitations of human memory requires that displays be kept simple, multiple-page displays be consolidated, window-motion frequency be reduced, and sufficient training time be allotted for codes, mnemonics, and sequences of actions Where appropriate, online access should be provided
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It is a process:
a goal-directed problem solving activity
informed by intended use, target domain, materials, cost, and feasibility
a creative activity a decision-making activity to balance
trade-offs
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- 1. Identifying needs and establishing
requirements for the user experience
- 2. Developing alternative designs to meet
these
- 3. Building interactive prototypes that can be
communicated and assessed
- 4. Evaluating what is being built throughout
the process and the user experience it
- ffers
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User-centered approach is based on:
Early focus on users and tasks: directly
studying cognitive, behavioral, anthropomorphic & attitudinal characteristics
Empirical measurement: users’ reactions and
performance to scenarios, manuals, simulations & prototypes are observed, recorded and analysed
Iterative design: when problems are found in
user testing, fix them and carry out more tests
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Not as obvious as you think:
those who interact directly with the product those who manage direct users those who receive output from the product those who make the purchasing decision those who use competitor’s products
Three categories of user (Eason, 1987):
primary: frequent hands-on secondary: occasional or via someone else tertiary: affected by its introduction, or will
influence its purchase
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Who are the stakeholders?
Check-out operators Customers Managers and owners
- Suppliers
- Local shop
- wners