Ocular vergence and visual-accommodation data were collected. in a preliminary investigation involving simulated monocular and binocular helmet-mounted display (HMD) configurations with varying scenic backgrounds and attentional instructions. A binocular eyetracking system was used to objectively measure vergence and accommodation. Photographic slides aligned and positioned at optical infinity were used to simulate HMD symbology and out-of-the-cockpit scenery. The accuracy of ocular vergence and the relative distance of visual accommodation were affected by the HMD configuration (binocular, monocular, one-eye-occluded), the content of the scenic background (clouds or mountains), the focus of attention (symbology or background), and the ocular characteristics of the observer (distance of the dark-vergence and -focus).