Context for Relating AT, Functional Needs, & Human Performance: Human Activity Assistive Technology (HAAT) Model (pp. 46-75 in Cook & Hussey)

• Human Performance may be viewed as "the result of a pattern of actions carried out to satisfy an objective"
  • Behavior is the pattern of actions (appropriate or inappropriate) leading to the result
  • Important to observe and measure as objectively as possible
  • Assessment is the active process of determining the worth of observations and measurements in a specific context
• "System" can include both human and AT
  • "System" performance versus "human" performance (e.g., AT can assist/enable)
    • Documenting the role of AT in performance and outcomes is a research/ clinical challenge
    • Side note: the ATOMS (Assistive Technology Outcomes Measurement System) project centered at UWM is working to come up with better metrics for documenting AT outcomes
  • Often useful to consider information flow within subsystems (e.g., displays, controls)
• Activities -- Recognize/specify the Need (or desire)
  • Functional result of human performance
  • Activities are determined or related to life roles
  • Activity accomplished by completing a set of tasks
  • Activity carried out within a context (environmental setting, social/cultural context, physical context)
  • Classification of activity performance areas: self-care, work/school, play/leisure
• "Human-Activity-Context" model commonly used in human factors engineering, ergonomics, psychology
  • HAAT model targets people with disabilities who are faced with an activity in a given context, and may use ATs to facilitate performance
• HAAT model: adds AT and broadens context
• Human as "Intrinsic Enabler"
  • "Human operator" with underlying abilities to perform activities/tasks
  • Classification into:
    • Sensory input, central processing, effectors
      • central: perception, cognition/memory, motor control (p. 82)
    • Example for motor control (p. 123): Speed-accuracy tradeoff (Fitts' Law), reaction time
  • Ability as basic trait a person brings to a new task
  • Skill is a level of proficiency (in performance)
    • "Learning" often involves breaking activity into tasks to master
  • Basic performance areas: self-care, work/school, play/leisure
• AT's as "Extrinsic Enablers"
  • Human-Technology Interface
    • may be unicausal (1-way, e.g., display, some controls) or bi-causal (2-way, e.g., body-powered below-elbow prosthetic, tennis racquet, pencil)
      • "Extended Physiological Proprioception (EPP" - bicausal interfaces that, through practice, become a natural "extension" of the person
    • Examples of interfaces: seating/positioning devices; control-display interfaces for computers and appliances ...
  • AT "Processors" - translate info and forces received from human into signals that are used to control activity output
  • Activity Outputs of the AT, for augmentation or replacement of human performance (from AT to activity)
    • communicating, moving self, manipulating objects
  • Environmental Interface (i.e., "HAAT System" boundary)
  • Examples very broad: mobility, augmentative communication, manipulation, sensory aids, ...
• Designing AT for Successful "Outcomes" Using HAAT Model
  • Motivation: "Outcomes" assessment becoming more and more a critical "driver" of service delivery
  • Consider performance of "system"
    • Often focus is on AT-Human interaction (interface design) and integration
    • Allocation (distribution) of functions between human and AT
    • Flexible allocation: consumer can vary degree of participation in the activity based on skills and needs (may increase or decrease over time)
  • Effectiveness - impact of "product" on consumer's life & needs ("Does it work?")
    • also must consider effects of errors (random, regular/periodic), e.g., loss of information, injury, embarrassment
  • Efficacy - ability of produce a desired result or effect ("Can it work?")
  • In addition to HAAT, there may also be constraints imposed on system performance
• Use in Typical Clin Rehab Engineering Design "Process"
  • Assess needs, goals (related to desired activities), skill
  • Determine AT system characteristics
  • Conceive design plan, system
  • Develop/deliver (and perhaps provide training)
  • Evaluate with client (perhaps iterate)

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