title: Real-Time Non-Intrusive Assessment of Viewing Distance during Computer Use.
abstract: To develop and test the sensitivity of an ultrasound-based sensor to assess the viewing distance of visual display terminals operators in real-time conditions.
  
  
  
  A modified ultrasound sensor was attached to a computer display to assess viewing distance in real time. Sensor functionality was tested on a sample of 20 healthy participants while they conducted four 10-minute randomly presented typical computer tasks (a match-three puzzle game, a video documentary, a task requiring participants to complete a series of sentences, and a predefined internet search).
  
  
  
  The ultrasound sensor offered good measurement repeatability. Game, text completion, and web search tasks were conducted at shorter viewing distances (54.4 cm [95% CI 51.3-57.5 cm], 54.5 cm [95% CI 51.1-58.0 cm], and 54.5 cm [95% CI 51.4-57.7 cm], respectively) than the video task (62.3 cm [95% CI 58.9-65.7 cm]). Statistically significant differences were found between the video task and the other three tasks (all p < 0.05). Range of viewing distances (from 22 to 27 cm) was similar for all tasks (F = 0.996; p = 0.413).
  
  
  
  Real-time assessment of the viewing distance of computer users with a non-intrusive ultrasonic device disclosed a task-dependent pattern.
authors: *MSc †PhD Department of Optics and Optometry, School of Optics and Optometry of Terrassa (MA, GC, EP-C, JG), and Department of Automatic Control, Terrassa School of Engineering (RP-M, BM), Universitat Politècnica de Catalunya · BarcelonaTech, Terrassa, Spain.
authors: Marc
authors: M
authors: Argilés
authors: Genís
authors: G
authors: Cardona
authors: Elisabet
authors: E
authors: Pérez-Cabré
authors: Ramon
authors: R
authors: Pérez-Magrané
authors: Bernardo
authors: B
authors: Morcego
authors: Joan
authors: J
authors: Gispets
mesh_terms: D000293:Adolescent; D000328:Adult; D003201:Computers; D004215:Distance Perception / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D020407:Internet; D008297:Male; D013997:Time Factors; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult