title: Assessing the benefits of "gaze-down" display location in complex tasks.
abstract: BACKGROUND
  Location of the image display is one of several factors that influence perceptual processing and endoscopic manipulation in minimal access surgery. Previous studies have proved the benefits of the gaze-down stance, as compared with the conventional gaze-up stance. This study investigates the effect of the gaze-down stance on the performance of a task with varying manipulative and perceptual demands.
  
  
  METHODS
  The participants in this study were 20 medical students. Each student performed endoscopic touching tasks under standard conditions using the Dundee Projection System (DPS) display, positioned to provide gaze-up and gaze-down stances. To increase task complexity, two kinds of manual coordination (unilateral vs bilateral) and three endoscope positions (different positions of misalignment) were used. The outcome measures were task execution time and number of errors.
  
  
  RESULTS
  Overall, the gaze-down stance reduced time and errors, as compared with the gaze-up display. However, the benefit obtained from the gaze-down stance was more significant in the more difficult tasks (bilateral task and 90 degrees misalignments).
  
  
  CONCLUSIONS
  The gaze-down stance reduces task time and errors, as compared with a gaze-up stance. The reduction in time and errors is more appreciable as task complexity increases.
authors.affiliation: Surgical Skills Unit, University of Dundee, Ninewells Hospital, Dundee, DD1 9SY, UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Omar
authors.forename: N J
authors.initials: NJ
authors.lastname: Wade
authors.forename: S I
authors.initials: SI
authors.lastname: Brown
authors.forename: A
authors.initials: A
authors.lastname: Cuschieri
mesh_terms: D010535:Laparoscopy / Q000592:standards*; D013647:Task Performance and Analysis; D014785:Vision, Ocular