Preferred Declination of the Line of Sight
研究了人们在看视觉目标和任务时偏好的视线俯角，发现平均偏好俯角为-34度，且头部姿势和距离有显著影响，但任务类型无影响。
This research concerned the angle at which people prefer to look down at visual targets and tasks. Thirty-two subjects participated in a study with four different head positions, two visual tasks, and two target distances. The overall preferred mean angle in the midsagittal plane below the Frankfurt Plane was -34 deg. Head position had significant effects on angle: subjects sitting with their heads upright preferred an average declination of -29 deg, but -40 deg when supine. Target distance also significantly affected the line-of-sight angle, with subjects preferring targets at 0.50 m to be at -38 deg, but targets at twice that distance at -30 deg. The task did not influence the preferred angle.