Preferred line of sight angle

Abstract

Recent experiments with 16 male and 16 female subjects indicated that they like to look down rather steeply at an average of −29^° below horizontal, s.d. 11·6^°, when sitting with trunk and head upright. This angle is steeper when the visual target is at 0·50 m distance (−33^°±11·3^°) but flatter when the target is at 1·00 m (−24^° ± 10·4^°). When head and trunk are reclined to 105^° behind horizontal, the overall angle of the preferred line of sight is reduced to −20^° ±11·7^° below horizontal, with −23^° (± 12·5^°) at 0·5 m and −16^° (±9·6^°) below horizontal at 1·0 m target distance. These preferred visual angles did not depend on the visual task. The finding that people look down much more steeply than listed in most human engineering design guides has obvious implications for the layout of workplaces where the task has a strong visual component, e.g. at computer workstations.

Keywords:

• Vision
• Posture
• Line of sight
• Eye rotation
• Computer workstation