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Human Activity / Assistive Technology (HAAT) Model

Mod1 Outline Rehab Science Clinical Rehab Rehab Terms HAAT Model Rehab Optim Telehealth
Part 4 (HAAT Model): | Outline | AT Definition | AT & Society | HAAT Model |


human activity assistive technology model, as a 3-section pie chart

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

  • HAAT (Human Activity - Assistive Technology) model: adds AT and broadens context
    • HAAT model targets people with disabilities who are faced with an activity in a given context, and may use ATs to gain access to the benefits of the activity and/or to facilitate performance
  • 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 a result
      • Important to observe and measure as objectively as possible
    • Assessment is the active process of determining the worth of observations (e.g., validity), then making appropriate measurements in a specific context
  • "System" can include both human and AT
    • "System" performance versus "human" performance (e.g., AT can assist/enable)
    • 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 (for participation)
    • 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
  • 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
      • Example for motor control: 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, often 2 directions) or bicausal (2-way)
        • Unicausal (to user - display; from user - control)
        • Bicausal & "Extended Physiological Proprioception" (EPP) - the concept that bicausal interfaces can, through practice, become a natural "extension" of the person (e.g., body-powered arm prosthetic, tennis racquet, pencil, certain hand tools)
      • Examples of interfaces:
        • seating/positioning devices
        • hand tools (eating, remote control, power drill, etc)
        • control-display interfaces for computers and appliances (eye-hand)
    • 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 and Environment 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 to 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 over time)

HAAT model, with focus on assistive technology components: interfaces, processor, activity output


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