Lecture 3:The Timely User Experience

Learning Outcomes

1. Introduction
2. Models of System Response Time (SRT) Impacts
3. Expectations and Attitudes
4. User Productivity and Variability in SRT
5. Frustrating Experiences
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   Introduction
   • With current computer, device, wireless and
   Internet technology, we have an increased
   thirst and expectation for fast response time
   – Loading graphics, audio, video, images,
   animation, etc. all impact how quickly
   we can do things in today’s society
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   Continued:
    Lengthy or unexpected system
   response time can produce:
   • Frustration
   • Annoyance
   • Eventual anger
    Speedy and quickly done work can
   result in users:
   • Learning less
   • Reading with lower comprehension
   • Making more ill-considered
   decisions
   • Committing more data-entry errors
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   Introduction (concluded)
   • System Response Time (SRT) is a key topic and concern for network designers,
   wireless manufacturers, telecommunications providers, and others
   • There are steps interface designers can take to improve the timely user experience
   – Designers can optimize web pages – it helps to reduce the number of queries
   and accesses to the network
   – Human reaction time is another factor
   – In practice, users seems to be bothered or not ???
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   Optimizing Design (example)
    The Earthdata Search (search.earthdata.-
   nasa.gov) indicates the geographic and temporal
   coverage of datasets before the
   data is downloaded. Here the
   user has selected two datasets
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   Models of SRT impacts
   • SRT definition:
   The number of seconds it takes from
   the moment users initiate an activity
   until the computer presents
   results on the display.
   • User think time:
   The number of seconds the user thinks before
   entering the next action
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   Models of SRT impacts (continued)
   • Designers of response times and display rates in HCI must consider:
   – Cost
   – User expectations
   – Speed of task performance
   • Overall majority of users prefer rapid interactions
   – Lengthy response times (seconds) are detrimental to productivity
   – Rapid response times (1 second or less) are preferable, but can increase errors for complex tasks
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   Expectations and Attitudes
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   Expectations and Attitudes
   • Users may achieve rapid task performance, low error rates,
   and high satisfaction if the following criteria are met:
   – Users have adequate knowledge of the objects and
   actions necessary for the problem-solving task
   – The solution plan can be carried out without delays
   – Distractions are eliminated
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   Expectations and Attitudes
   • Three primary factors that influence user expectations and
   attitudes regarding SRT are:
6. Previous experiences
7. Individual personality differences
8. Task differences
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   Expectations and Attitudes (concluded)
   • These conjectures may play a role in choosing the optimum interaction
   speed:
   – Novices may exhibit better performance with somewhat slower
   response times.
   – When there is little penalty for an error, users prefer to work more
   quickly.
   – If users have experienced rapid performance previously, they will expect
   and demand it in future situations.
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   User Productivity and Variability in SRT
   • Repetitive tasks
   • Problem solving tasks
   • People are willing to pay substantial amounts of money to reduce
   the variability in their lives, e. g. the insurance industry
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   User Productivity and Variability in SRT (concluded)
   • Progress indicators reassure users that
   the process of uploading photos from
   Picasa to the web is underway, and
   how far it has gone already.
   • They also allow users to see the results
   or to cancel uploads
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   Frustrating experiences
   • Since frustration, distractions, and interruptions can impede smooth
   progress, design strategies should enable users to maintain concentration.
   • Three initial strategies can reduce user frustration 
9. Reduce short-term and working memory load
10. Provide information abundant interfaces
11. Increase automaticity
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    Reducing User Frustration
    • Increase server capacity, network speed, and network reliability
    • Improve user training, online help, and online documentation including
    tutorials
    • Redesign instructions and error messages
    • Increase research on user frustration
    • Catalyze public discussion to raise awareness
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    SRT Guidelines
    • Users prefer shorter response times
    • Longer response times (> 15 seconds) are disruptive
    • Shorter response time leads to shorter user think time
    • A faster pace may increase productivity, but it may also increase error
    rates
    • Response time should be appropriate to the task
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    SRT Guidelines concluded:
    • Users should be advised of long delays
    • Modest variability in response time is acceptable
    • Unexpected delays may be disruptive
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    Summarize the important points
12. What we have discussed in week 2 ? Summarize some points.
13. Which is the most likely topic for today’s class ?
    Can you explain why ?
14. Which is the least likely topic for today’s class ?
    Can you justify your opinion ?