Principles and Practice of Assistive Technology - Today: The Human User (I) - Activity-Limiting Disabilities and Information Processing Model

Sep 5, 2026

Lecture notes on Activity-Limiting Disabilities within assistive technology design, selection, and use, focusing on the human user as an “AT operator.” The material quantifies prevalence and highlights uneven impact across populations, then introduces an information processing model for users with disabilities. It outlines strategy for AT system designers, mapping what users can do, cannot do, and will do, and details sensory and central processing functions. Terminology and capability-versus-deficit examples cover visual, auditory, and somatosensory senses, concluding with implications for AT design and potential supports such as corrective lenses.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

Activity-Limiting Disabilities

Prevalence and socioeconomic impact

Activity, cost, and distribution overview

Human User Framework (AT Operator)

Information processing model

Implications for AT design, selection, use

Strategy for AT System Designer

Remaining function vs. lost function

Intrinsic enablers: sensors, central processing, effectors

Terminology and Senses

Proprioceptive, exteroceptive, interoceptive

Kinesthetic and vestibular senses

Sensory Function and AT Use

Exteroceptive data acquisition

Proprioceptive data acquisition

Limitations: sensitivity and range

Visual, Auditory, and Somatosensory Functions

Visual scanning, tracking, acuity, range

Auditory thresholds and hearing loss deficits

Somatosensory feedback and deficits

Posture, Position, and Integration

Sensory integration for effective AT use

Example: prismatic lenses for mismatch

Central Processing Functions

Perception, cognition, psychosocial factors

Motor control and motor planning

10/1/2012 6.S196 / PPAT: Principles and Practice of Assistive Technology Today: The Human User (I) [C&H Ch. 3] Monday, 1 Oct. 2012 Prof. Seth Teller Activity-Limiting Disabilities • Widespread – Tens of millions of Americans have a limitation that affects a major life activity (e.g. working, attending school, managing a household) • Unevenly distributed – Disproportionately affect minorities, elderly, and those with lower socioeconomic status • Expensive – Disability-related costs exceed hundreds of billions of dollars annually in the U.S. alone 10/1/2012 Today • Introduction of “Information processing model” of a human user with a disability • Consideration of how disabilities affect human performance model • Implications of disabilities for design, selection and use of assistive technologies Review: HAAT Model • Someone doing something, somewhere, involving the use of an assistive technology Today’s focus: implications of disabilities for AT design, selection, use 10/1/2012 Strategy for AT System Designer • Focus on remaining (not on lost) function • Determine what user can do (skills)… what user cannot do (limitations)… and what user will do (motivation) • Intrinsic enablers of human performance: – Sensors – Central processing – Effectors • Elements of information processing model Information Processing Model Central Processing Perception ~~ ~~ Cognition ~~ ~~ Psychosocial ~~ ~~ Motor Control Memory Effectors 10/1/2012 Terminology • Proprioceptive sense – Relation of body parts, strength of effort • Exteroceptive sense – Sensation of the world external to the body • Interoceptive sense – Sensation of pain, hunger, movement of organs • Kinesthetic sense – Sensation of motion of the body parts • Vestibular sense – Sensation of balance and spatial orientation Sensory Function and AT Use • Obtain data from environment – Exteroceptive systems – Visual, auditory, tactile sensory systems – Levels of light, sound, mechanical pressure • Obtain data from body – Proprioceptive, kinesthetic, vestibular systems – Body motion, limb motion, head orientation • Limitations: – Sensitivity (minimum detectable levels) – Range (variation in size, amplitude, magnitude) 10/1/2012 Visual Function • Visual scanning – Finding a target in a field of several targets • Visual tracking – Following during target or head/body motion • Visual acuity – Distinguishing a small or low-contrast target • Visual range – Visual attention as the target location (in the visual field) or depth (in the scene) varies Capabilities and Deficits • Visual acuity – Object size, color, contrast; inter-object spacing – Inability to detect/distinguish items, background • Visual field and range – Ordinary range > 165o to either side of midline – Loss in visual field(s), achievable range of gaze • Tracking, scanning, vergence, accommodation – Focus on target as it moves laterally or in depth – Inability to stabilize, transfer gaze to new target • Implications for AT design, use? 10/1/2012 Auditory Function • Auditory thresholds – Audible sound amplitude (dB w. r.t. reference) – Audible sound frequency (Hz) • Deficits in degree and type of hearing loss – Loss of input information (from environment) – Loss of feedback (from user’s own speech) • Important in consideration of context – Use in a quiet vs. loud environment – Power, form factor considerations • Other implications for AT design, use? Somatosensory Function • “Where body ends and the world begins” • Peripheral sense, feedback to motor system – Pressure – Hot-cold – Tactile – Kinesthetic • Deficits can result in tissue damage – Especially important for seating/cushion systems • Other implications for AT design, use? 10/1/2012 Sensing for Posture and Position • Posture and body position control are fundamental to effective

FAQs

How do Activity-Limiting Disabilities influence assistive technology design?

They shape how users perceive information, process it, and execute motor control. The notes stress implications for design, selection, and use of assistive technologies based on disability-driven performance limits.

What strategy should an AT system designer follow?

Focus on remaining (not lost) function, determine what the user can do (skills), cannot do (limitations), and will do (motivation). This supports an AT system aligned with user capabilities.

Which sensory functions are covered to explain AT use?

The lecture covers visual function (scanning, tracking, acuity, range), auditory function (thresholds and hearing loss deficits), and somatosensory function (pressure, hot-cold, tactile, kinesthetic). It also discusses limitations such as sensitivity and range.

Sep 5, 2026

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