(Delleman 2004), therefore, working in this manner is likely to result in discomfort
in the neck. Using a document holder that presents source material at the same height
and at the same distance as the screen has been shown to reduce postural loading
on the neck muscles considerably (Pheasant and Haslegrave 2006). It is also worth
keeping in mind that documents located on the desk surface are presented at a different
viewing distance from that of the screen. Therefore, each time the user looks
from the document to the screen and back again they have to refocus their eyes. Such
refocusing increases the workload for the eyes and many users might experience eye
fatigue or headaches as a result.