Head Movements as a Function of Field-of-View Size on a Helmet-Mounted Display

Measurements were made of subjects' head movements as they found and memorized the position of targets located around them. Four factors were manipulated: the size of the field-of-view (FOV) with which they could view the targets, the number of targets, the background against which the targets were presented (blank or terrain), and the search instructions (slow or fast). The targets and terrain were viewed on a binocular helmet-mounted display. The dependent variables included measures of the amount of head displacement and head velocity. In the slow search trials, small FOVs produced significantly more head displacement and lower head velocities than did the large FOVs. In the fast search trials, head velocity increased with increasing FOV. The results are interpreted in terms of the disruptive effects of small FOVs on the efficient use of coordinated head and eye movements to acquire spatial information.