Ergonomics User interfaces Jaana Holvikivi 2014

The Discipline of Ergonomics Ergonomics (or human factors) is  the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and  the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance. International Ergonomics Association: Helsinki Metropolia University of Applied Sciences

Ergonomics  Derived from the Greek ergon (work) and nomos (laws) to denote the science of work,  ergonomics is a systems-oriented discipline  ergonomics promotes a holistic approach in which considerations of physical, cognitive, social, organizational, environmental and other relevant factors are taken into account Helsinki Metropolia University of Applied Sciences

Human-machine systems Ergonomics is the study of the interaction between people and machines. Systems can be improved by:  designing the user interface to make it more compatible with the task and the user  changing the work environment to make it safer and more appropriate to the task  changing the task to make it more compatible with user characteristics  changing the way work is organized to accommodate people’s psychological and social needs Helsinki Metropolia University of Applied Sciences

Domains of specialization  Physical ergonomics is concerned with human anatomical, anthropometric, physiological and biomechanical characteristics as they relate to physical activity. Relevant topics include  working postures,  materials handling,  repetitive movements,  work related musculoskeletal disorders,  workplace layout,  safety and  health. Helsinki Metropolia University of Applied Sciences

Domains of specialization  Cognitive ergonomics is concerned with mental processes, such as perception, memory, reasoning, and motor response, as they affect interactions among elements of a system. (Relevant topics include mental workload, decision-making, skilled performance, human-computer interaction, human reliability, work stress and training.)  Organizational ergonomics is concerned with the optimization of sociotechnical systems, including their organizational structures, policies, and processes. Helsinki Metropolia University of Applied Sciences

General ergonomics checklist 1.Job analysis 2.Work organization 3.Workspace design 4.Physical demands 5.Mental demands 6.Human-machine interaction 7.Work environment 8.Workforce characteristics 9.Job stress 10.Occupational background (abbreviated from Bridger, p ) Helsinki Metropolia University of Applied Sciences

General principles for control – display integration PrincipleDescription ImportanceMost important items must be in the most advantageous positions Frequency of useMost frequently used items must be in the most advantageous positions FunctionUse grouping principles to group items by function Location compabilityLocate control near their corresponding displays Conceptual compabilityLayout and use of controls should be consistent with user/ popular stereotype Sequence in real tasksUse link analysis to optimize layout in relation to the sequence of movements Effort balanceShare workload between dominant and nondominant hands Helsinki Metropolia University of Applied Sciences

Mental workload Consequences of mental strain (ISO 10075)  Warming-up effect  Mental fatigue, fatigue-like states:  monotony,  lack of vigilance,  mental satiation (strong rejection) Helsinki Metropolia University of Applied Sciences

Factors affecting mental workload (Bridger p. 482)  ambiguity of the goal  competing goals  unclear serving strategy (priorities)  task complexity (too low, too high)  adequacy of information  signal discriminability  redundancy  parallel versus serial processing  time-sharing (switching attention between tasks) Helsinki Metropolia University of Applied Sciences

Factors affecting mental workload (cont.)  delays in system response  mental models  recognition vs recall  controllability  error tolerance  environmental design  social interaction  time pressure Helsinki Metropolia University of Applied Sciences

Some characteristics of poor performance resulting from excessive work demands (p. 484)  slower reaction time  increased time to complete task  increased forgetfulness  inability to concentrate  lapses of attention  missing or misinterpreting signals  omitting steps in a procedure Helsinki Metropolia University of Applied Sciences  increased need for instruction  narrowing of attention  erratic operation of controls  mistiming of actions  making unnecessary responses  carrying out irrelevant tasks

General principles of software ergonomics Appropriate software 1.is suitable to the task 2.is easy to use and adaptable 3.provides feedback on system performance 4.works at the user’s own pace 5.does not “spy” on the user. Helsinki Metropolia University of Applied Sciences

1. Software is suitable to the task  it presents users with no unnecessary obstacles or problems  is not necessarily complex or elaborate  supports the user in the effective and efficient completions of the task  present the user only with the information related to the completion of the task while the task is being carried out Helsinki Metropolia University of Applied Sciences

2. Software is easy to use and adaptable  is easy to master  input and output formats are appropriate to the task requirements and user goals  actions that can be allocated to the interface software are carried out automatically without user involvement (e.g. default values)  uses dialogue appropriate to the user’s ability  has an interface adaptable to different skill levels  minimizes consequences of error: lost data are recoverable & “undo button” Helsinki Metropolia University of Applied Sciences

3. Software provides feedback on system performance  timely error messages  appropriate level of information  task dependent help on request Helsinki Metropolia University of Applied Sciences

4. Software works at the user’s own pace  user “drives” the system  system displays all keystrokes when they are made  system response time and response time variability is minimized  during performance of a task in which data are changed, the original data remain accessible until no longer required by the tasks Helsinki Metropolia University of Applied Sciences

5. Software does not “spy” on the user  no covert monitoring of user performance  users are informed of any recording of their input  emphasis on quality rather than quantity Helsinki Metropolia University of Applied Sciences

Computer hassles By RA Hudiburg, 1998 Test your computing stress:  Listed below are a number of ways in which a person can feel hassled by computers and computer technology. Respond to each hassle by circling a 0, 1, 2, or 3 to indicate how SEVERE the hassle has been for you during the past TWO MONTHS.  SEVERITY:  0 - not at all ; 1 - somewhat severe; 2 - moderately severe ; 3 - extremely severe 19

HASSLES 1. computer system is down 2. lost in the computer 3. poorly documented software 4. computer hardware failure 5. computer keyboard lockup 6. programming error 7. illegal input message 8. updated software requirements 9. poor user/computer interface 10. slow program speed 11. slow computer speed 12. poorly written computer documentation 13. incompatible software program 14. incomprehensible computer instructions 15. outdated computer skills 16. increased time demands 17. electrical surges - data are lost 18. lost data 19. lost program 20. crashed program 21. crashed system/ lockup 22. damaged storage media - disks, tapes 23. need to update skills 24. keyboard typing errors 25. need to learn new software 26. forgot to save work 27. keyboard paralysis 28. uninformative computer conversations 29. violent language of computers 30. too much computer information 31. too little computer information 32. software confusion 33. lack of help with a computer problem 34. lack of computer expertise 35. increased computer use expectations 36. lack of computer application software 37. obsolete computers 20