title: Visually guided tracking on a handheld device: can it be used to measure visuomotor skill in shift workers?
abstract: OBJECTIVE
  We introduced a new visually controlled tracking task that can be assessed on a handheld device in shift workers to evaluate time-of-day dependent modulations in visuomotor performance.
  
  
  BACKGROUND
  Tracking tasks have been used to predict performance fluctuations depending on time of day mainly under laboratory conditions. One challenge to an extended use at the actual working site is the complex and fixed test setup consisting of a test unit, a monitor, and a manipulation object, such as a joystick.
  
  
  METHODS
  Participants followed an unpredictably moving target on the screen of a handheld device with an attachable stylus. A total of 11 shift workers (age range: 20-59, mean: 33.64, standard deviation: 10.56) were tested in the morning, the evening, and the night shift in 2-hr intervals with the tracking task and indicated their fatigue levels on visual analogue scales. We evaluated tracking precision by calculating the mean spatial deviation from the target for each session.
  
  
  RESULTS
  Tracking precision was significantly influenced by the interaction between shift and session, suggesting a clear time-of-day effect of visuomotor performance under real-life conditions. Tracking performance declined during early-morning hours whereas fatigue ratings increased.
  
  
  CONCLUSIONS
  These findings suggest that our setup is suitable to detect time-of-day dependent performance changes in visually guided tracking.
  
  
  CONCLUSIONS
  Our task could be used to evaluate fluctuations in visuomotor coordination, a skill that is decisive in various production steps at the actual working place to assess productivity.
authors.forename: Patricia
authors.initials: P
authors.lastname: Hölzle
authors.forename: Christian
authors.initials: C
authors.lastname: Tatarau
authors.forename: Joachim
authors.initials: J
authors.lastname: Hermsdörfer
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D034201:Computers, Handheld; D005260:Female; D006225:Hand / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016272:Occupational Health; D013647:Task Performance and Analysis; D013996:Time and Motion Studies; D055815:Young Adult