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Virtual University Human-Computer Interaction. Lecture 36 Behavior & Form – Part IV. Imran Hussain University of Management and Technology (UMT). In Last Lecture …. Evaluation Conceptual framework for developing an interactive product - PowerPoint PPT Presentation
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Virtual University - Human Computer Interaction1 © Imran Hussain | UMT
Imran Hussain
University of Management and Technology (UMT)
Lecture 36
Behavior & Form – Part IV
Virtual University
Human-Computer Interaction
Virtual University - Human Computer Interaction2 © Imran Hussain | UMT
In Last Lecture …
• Evaluation– Conceptual framework for developing an interactive product
– How we can use this framework to identify certain usability problems
– Tactical vs. strategic usability
Virtual University - Human Computer Interaction3 © Imran Hussain | UMT
Usability can be tactical as well as strategic
Virtual University - Human Computer Interaction4 © Imran Hussain | UMT
In Today’s Lecture …
• Undo functionality
• Files and Save functionality
Virtual University - Human Computer Interaction5 © Imran Hussain | UMT
Understanding Undo
Virtual University - Human Computer Interaction6 © Imran Hussain | UMT
Users and Undo
• Reverses previous action
Virtual University - Human Computer Interaction7 © Imran Hussain | UMT
User Mental Models of Mistakes
• Humans make mistakes
• Programmers should not think of human mistakes as errors
• Programmers follow implementation model
• Human being do not like to be told that they have make an error so the software should not contradict users
Virtual University - Human Computer Interaction8 © Imran Hussain | UMT
Undo Enables Exploration
• Users are like explorers using a tool
• They like experiment to see what they can achieve with computer
• Undo reassures user if they are in trouble then this function helps them to reverse any action
Virtual University - Human Computer Interaction9 © Imran Hussain | UMT
Virtual University - Human Computer Interaction10 © Imran Hussain | UMT
Designing an Undo Facility
• Undo not directly related to goal of user
• Users have different models of undo– Novice: help
– Intermediate: deleted data
– Expert: stack of procedures that can be undone
• Undo should be designed to support exploration and not for reversing errors
• Undo should be global-wide function
Virtual University - Human Computer Interaction11 © Imran Hussain | UMT
Types of Undo
• Incremental and Procedural Actions
• Blind and Explanatory Undo
• Single and Multiple Undo
• Redo
Virtual University - Human Computer Interaction12 © Imran Hussain | UMT
Incremental and Procedural Actions
• Procedural component• What the user did?
• Data component• What information was affected?
• Incremental actions there is both procedural component and data component
• Procedural actions do not have data component– These operations act on data but do not add or delete the data
Virtual University - Human Computer Interaction13 © Imran Hussain | UMT
Blind and Explanatory Undo
• Blind Undo– There is no indication what the operation is
• Explanatory Undo– There is some textual and visual information of the particular operation
Virtual University - Human Computer Interaction14 © Imran Hussain | UMT
Single Undo
• Most common form of undo• It reverses the effects of the most recent user’s action
Virtual University - Human Computer Interaction15 © Imran Hussain | UMT
Virtual University - Human Computer Interaction16 © Imran Hussain | UMT
Other Models for Undo-like Behavior
• Comparison
• Category-specific undo
• Deleted data buffers
• Milestoning and reversion
• Freezing
Virtual University - Human Computer Interaction17 © Imran Hussain | UMT
Other Models for Undo-like Behavior
• Comparison
• Category-specific undo• Deleted data buffers
– Saves the user having to remember exact undo operations and their sequence
• Milestoning and reversion– For significant changes make a milestone copy, use revert option to
access it
• Freezing– Lock the document so certain aspects cannot be changed
Virtual University - Human Computer Interaction18 © Imran Hussain | UMT
What’s wrong with saving changes to files …
Virtual University - Human Computer Interaction19 © Imran Hussain | UMT
Saving Changes to Files
• Programs and data files exist in 2 places at the same time
• Data and program managed by file system– Explorer (Windows)
– Finder (Mac)
• The file system and the disk storage facility it manages is the primary cause of disaffection in computer users
Virtual University - Human Computer Interaction20 © Imran Hussain | UMT
Virtual University - Human Computer Interaction21 © Imran Hussain | UMT
Virtual University - Human Computer Interaction22 © Imran Hussain | UMT
Virtual University - Human Computer Interaction23 © Imran Hussain | UMT
Virtual University - Human Computer Interaction24 © Imran Hussain | UMT
Let’s consider the ‘save as’ dialog box …
Virtual University - Human Computer Interaction25 © Imran Hussain | UMT
Virtual University - Human Computer Interaction26 © Imran Hussain | UMT
what’s the point in having a redundant dialog box that users always click yes?
…
Virtual University - Human Computer Interaction27 © Imran Hussain | UMT
what’s the point in a function that will confuse new users and they might click ‘no’?
Virtual University - Human Computer Interaction28 © Imran Hussain | UMT
.. confuses possibility with probability (poor assumption)
Virtual University - Human Computer Interaction29 © Imran Hussain | UMT
… why would someone close the document if they didn’t want the changes
Virtual University - Human Computer Interaction30 © Imran Hussain | UMT
… why does it ask for saving changes when you are done and not when making them?
Virtual University - Human Computer Interaction31 © Imran Hussain | UMT
saving changes -------- closing doc(compare with writing in a notebook)
when user closes doc, this is the time the differences between the memory and disk need to be reconciled
no obvious connection, e.g.- erasing notes when closing book- discarding changes when we leave room
Virtual University - Human Computer Interaction32 © Imran Hussain | UMT
Reason?
implementation model is rendered as interface for users
Virtual University - Human Computer Interaction33 © Imran Hussain | UMT
Problems with implementation model …
Virtual University - Human Computer Interaction34 © Imran Hussain | UMT
What happens when I try to rename a file …
Virtual University - Human Computer Interaction35 © Imran Hussain | UMT
Virtual University - Human Computer Interaction36 © Imran Hussain | UMT
Virtual University - Human Computer Interaction37 © Imran Hussain | UMT
Q: What’s the function of the ‘save as’ window?Ans: placing and naming a file
Virtual University - Human Computer Interaction38 © Imran Hussain | UMT
I close the ‘save as’ dialog box, go to ‘explorer’, and try renaming again …
Virtual University - Human Computer Interaction39 © Imran Hussain | UMT
Virtual University - Human Computer Interaction40 © Imran Hussain | UMT
Virtual University - Human Computer Interaction41 © Imran Hussain | UMT
Another example:
What happens when I then open the document make some changes that don’t make difference to the contents of the file …
Virtual University - Human Computer Interaction42 © Imran Hussain | UMT
Virtual University - Human Computer Interaction43 © Imran Hussain | UMT
Virtual University - Human Computer Interaction44 © Imran Hussain | UMT
Virtual University - Human Computer Interaction45 © Imran Hussain | UMT
Virtual University - Human Computer Interaction46 © Imran Hussain | UMT
So why do we have these problems …
Virtual University - Human Computer Interaction47 © Imran Hussain | UMT
The Computer’s File System
• Data and program managed by file system– Explorer (Windows)
– Finder (Mac)
• File system is an internal facility and shouldn’t affect the user
• Software applications (you) treat file system (a car) just like the OS (a mechanic) does
Virtual University - Human Computer Interaction48 © Imran Hussain | UMT
Let’s say you want to create a copy for archive …
[no explicit function for creating copy
have to use ‘save as’]
Virtual University - Human Computer Interaction49 © Imran Hussain | UMT
Virtual University - Human Computer Interaction50 © Imran Hussain | UMT
Virtual University - Human Computer Interaction51 © Imran Hussain | UMT
Virtual University - Human Computer Interaction52 © Imran Hussain | UMT
… have to close ‘hci2.doc’, go to explorer, and then reopen original file
Virtual University - Human Computer Interaction53 © Imran Hussain | UMT
And now a perfectly reasonable scenario:
have made changes to doc (without saving) and now want to create a copy and keep on working …
Virtual University - Human Computer Interaction54 © Imran Hussain | UMT
Virtual University - Human Computer Interaction55 © Imran Hussain | UMT
Virtual University - Human Computer Interaction56 © Imran Hussain | UMT
… invoke ‘save as’ ..
… new file ‘hci2.doc’ contains changes, not ‘hci.doc’
Virtual University - Human Computer Interaction57 © Imran Hussain | UMT
Virtual University - Human Computer Interaction58 © Imran Hussain | UMT
I work on new file and delete those recent changes ..
Virtual University - Human Computer Interaction59 © Imran Hussain | UMT
Virtual University - Human Computer Interaction60 © Imran Hussain | UMT
… now I reopen the original file …
Virtual University - Human Computer Interaction61 © Imran Hussain | UMT
Virtual University - Human Computer Interaction62 © Imran Hussain | UMT
Virtual University - Human Computer Interaction63 © Imran Hussain | UMT
… changes lost forever!
Virtual University - Human Computer Interaction64 © Imran Hussain | UMT
Implementation Model vs. Mental Model
• Users view electronic documents just like printed documents