Understanding Interaction: Errors, HCI Laws, and Ergonomics in Human-Computer Interaction, Study notes of Information Technology

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ERRORS, HCI LAWS, &

ERGONOMICS

Week 4 – What Do We Know About Interaction? Tuesday (7/12)

OVERVIEW OF TODAY’S CLASS

• (^) Ergonomics: A Practical Introduction
  • (^) HW#3 – Ergonomics of Computer Usage
• (^) Review
• (^) Errors
  • (^) Slips and mistakes
• (^) HCI Laws
  • (^) Power Law of Practice, Hick’s Law, Fitts’ Law
• (^) Group Activity: Fitts’ Law Quizzo

WHY ERGONOMICS?

• (^) Musculoskeletal disorders (MSDs), often referred to as ergonomic injuries, accounted for 28% of all workplace injuries and illnesses requiring time away from work in 2009. (Occupational Safety and Health Administration, OSHA)
• (^) Ergonomic injuries cost an average of $12.7 billion annually for workers compensation. (Liberty Mutual Insurance, 2008)
• (^) 76% of American households have one or more computers; 52% own a laptop. (Pew Internet & American Life Project, 2010)

ERGONOMIC RISKS

• (^) Computer work presents ergonomic risks due to:
  • (^) Fixed and often awkward postures that are often maintained for too long.
  • (^) Repetitive and sometimes forceful movements.
  • (^) Compression on hard or sharp edges of work surfaces.
  • (^) High pace of movements that does not allow sufficient recovery time from the effects of these movements.
• (^) Computer ergonomic hazards are related to workstation design, job design and work practices, repetitive motion, posture, etc.

REDUCE YOUR RISK AND PREVENT INJURY

• (^) Positioning the Screen
• (^) Positioning Reference Documents
• (^) Mouse Use and Position

WORKSTATION SETUP

HW#

• (^) Submit checklist in class on Thursday
• (^) Submit written summary to Blackboard Assignments folder by 9:15am on Thursday (7/14) - (^) Don’t forget the academic honesty statement!

REVIEW What have we learned so far?

WEEK 2: WHAT IS GOOD DESIGN?

• (^) When people make errors with technology, they often blame themselves; in reality, most errors are the result of bad design. - (^) If people can’t figure out what to do, there is a gulf of execution - (^) If people can’t figure out if they did the right thing, there is a gulf of evaluation
• (^) Good design uses knowledge in the world to take advantage of the speed and efficiency of users’ STM and help them recognize what to do.
• (^) However, designers can also use knowledge in the head to take advantage of the storage capacity of users’ LTM and help them recall what to do.

WEEK 3: WHAT DO WE KNOW ABOUT USERS?

• (^) Users’ attention is selective, limited and influenced by the importance of stimuli. - (^) Take advantage of what we know about cognition by using Gestalt Principles of Perception to visually organize information.
• (^) Users develop mental models to represent their underlying understanding of how a system works.
• (^) To help users develop more accurate models, designers can use constraints to limit the number of possibilities.
• (^) Novices become experts via exploratory , automatic , and/or transfer of learning.

TWO TYPES OF ERRORS

• (^) People make errors routinely, especially when it comes to using technology.
• (^) Errors come in two forms:
  • (^) Slips result from automatic behavior
    • (^) Form the right goal but perform the wrong action
  • (^) Mistakes result from conscious deliberations
    • (^) Form the wrong goal

SLIPS

• (^) You know how to complete the task but you somehow get off track while doing it - (^) Show up frequently in skilled behavior - (^) Typically due to lack of attention - (^) Remember, attention is selective and limited! - (^) Usually easy to detect
• (^) 6 types of slips:
  • (^) Capture errors
  • (^) Description errors
  • (^) Data-driven errors
  • (^) Associative activation errors
  • (^) Loss-of-activation errors
  • (^) Mode errors

SLIPS: DESCRIPTION ERRORS

When the correct action is performed on the wrong object.

• (^) Typically occur when the intended action has much in common with other possible actions, especially when the right and wrong objects are physically near each other.
• (^) Everyday examples:
• (^) Pouring orange juice into your cereal
• (^) Throwing laundry into the toilet
• (^) Technology examples:
• (^) Pressing “Cancel” instead of “OK”
• (^) Putting your password into the username box

SLIPS: DATA-DRIVEN ERRORS

When actions are driven by the arrival of attention-grabbing sensory data.

• (^) Typically occur when an intended action is automatic; external data can be unconsciously processed to interfere with the intended action.
• (^) Everyday example:
• (^) Start going straight when the turn arrow lights up green
• (^) Saying the name of a nearby object instead of what you intended
• (^) Technology example:
• (^) Putting the name of the person you’re talking to in the “to” field instead of the person you’re e-mailing
• (^) Clicking the “OK” button on a pop-up window without reading what it says