Maxwell J. Wells

Virtual Chess: Meaning Enhances Users' Sense of Presence in Virtual Environments

A mooring anchor made up of a solid, heavy, cylindrical body from which extend rigid upper and lower cross arms that have flukes at the outer ends. The cross arms are spaced at ninety degree intervals around the circumference of the body. The upper cross arm is located appreciably higher on the body than is the lower cross arm. An eye affords a convenient means of attaching a chain or cable. This anchor is intended to provide a good means of anchoring buoys to bottoms that are either of sand or mud. It has no moving parts.

Foreground/Background Manipulations Affect Presence:

A possible relation between vection and presence is discussed. Two experiments examined the hypothesis that “presence” is enhanced by manipulations which facilitate interpreting visual scenes as “background.” A total of 39 participants in two experiments engaged in a pursuit game while in a virtual visual environment generated by an HMD and rated their experience of “presence” on 5 questions. Experiment 1 compared two viewing conditions: visual scene masking at the eye and a paper mask mounted on the screen with the same 60° FOV, and showed that presence was enhanced by eye masking relative to screen masking. Experiment 2 replicated these findings with a double-blind experimental design.

Exploring the Influence of a Virtual Body on Spatial Awareness

A virtual reality study explored the potential for a virtual body (VB) to enhance a participants spatial awareness of a virtual environment (VE) by providing an invariant, subtle point of reference for object positioning. The study used the ecological metric of perceived reachability as the manifestation of spatial awareness. Nine subjects entered a VE and performed a maximum virtual reach estimation task in which VB configuration (full-body, hand-only, no-body) and target height (low, medium, high) were manipulated. Estimations of reach were more significantly accurate for low target heights. This seemed most attributable to the influence of the more richly patterned visual background for that condition. A complex interaction between VB configuration and target height indicates that the specific VB used may impact observed performance. Subjective comments also indicate a perceived utility of a full-body virtual body as a reference point for spatial tasks. Results are discussed in regard to potential design implications and future research opportunities.

Using Target Replacement Performance to Measure Spatial Awareness in a Helmet-Mounted Simulator

Measurements were made of the ability of 20 subjects to acquire 3, 6 or 9 stationary visual targets and then replace them after they had been removed. The targets were viewed with various sized fields-of-view (FOVs) using a Visually Coupled Airborne Systems Simulator (VCASS), which was mounted on the head and which used head position information to provide space-stabilized computer-generated images. Targets were presented with a blank background or a terrain background. Subjects were instructed to use as much time as they required or to be as quick as possible searching for the targets. Mean times to search for the targets were faster with the larger FOVs and faster with fewer targets. Replacement accuracy was not sensitive to the FOV but decreased with increasing number of targets. Search times were slower, but replacement accuracy was greater with a terrain background than with a blank background. In the fast search conditions, the number of guessed target replacements decreased with decreasing numbers of targets and increasing FOV. It is concluded that target replacement performance was sensitive to manipulation of the independent variables and as such is a potentially useful metric of spatial awareness.

The Effect of Increasing Task Complexity on the Field-of-View Requirements for a Visually Coupled System

Ten subjects performed a task on a head-coupled simulator using various sized fields-of-view (FOVs). The task required them to visually acquire, remember the location of, monitor and shoot 3 or 6 objects. In addition they were required to perform a secondary tracking task. Performance at monitoring and shooting the objects decreased with decreasing FOV size and increasing number of objects. Secondary task performance also decreased with decreasing FOV. The ability to recall the location of objects was unaffected by changes in FOV size. However, tracking performance was degraded while subjects used smaller FOVS to find and learn the location of objects. The results indicate that although visual search performance can be maintained with small FOVs, it is done in a manner which may compromise performance at other tasks.

The Effects of Head and Sensor Movement on Flight Profiles during Simulated Dive Bombing

A dive bombing mission was performed in a simulator by 5 experienced USAF pilots. Their view out of the cockpit was provided by an aircraft-fixed or head-steered sensor. Despite significant differences in performance with the two sensors, the mean flight profiles flown with each sensor were similar. However, with the head-steered sensor, some subjects made consistently different head movements. The same subjects also flew different flight profiles. These subjects exploited the mobility of the head-steered sensor to make large amplitude head displacements during ascent. As a result, they sighted the target earlier. It is shown that these early-sighting subjects made changes to their flight profiles during ascent which allowed them, during descent, to aim their aircraft at the target earlier, while higher. Consequently, the early-sighting subjects released their bombs significantly higher than the late-sighting subjects (high bomb release is beneficial to aircraft survival).

Comparison of head-steered and aircraft-fixed infrared imagery for employing the AGM-65 Maverick missile

Eight veteran USAF fighter pilots, experienced with AGM-65 Maverick air-to-ground missiles, flew a night, low-level ground attack mission in a flight simulator equipped with a helmet-mounted display (HMD). The mission was performed by delivering five Maverick missiles against ground vehicles using either an aircraft-fixed forward-looking infrared (FLIR) sensor image on a head-up display (HUD) or a head-steered FLIR as the missile aiming device. Additionally, the pilots employed their weapons by two methods: fixing and launching missiles singly or in varying numbers (multiple method). The purpose of the experiment was to determine what, if any, advantage there is to employing the AGM-65 using the HMD FLIR image to slew the missile seeker onto the target versus the conventional method of using the FLIR image displayed on the HUD. With a head-steered sensor (and fixing and launching weapons singly) subjects released their weapons quicker (14.6 second interval between launches vs. 17.1 sec.), at a higher altitude (1739 feet vs. 1603 ft.), and slightly farther from the target (3.42 nautical miles vs. 3.37 nm). Furthermore, data indicated the pilots looked farther off-boresight when searching for and locking the weapon onto a target, thereby more effectively using the full field-of-regard of the missile seeker. The participants also contributed their opinions of the advantages and disadvantages of the two mechanizations.

Interview: A Software Tool for Interface Design

Interview is a software tool for designing, specifying and visualizing human-machine interfaces. The design of the tool began with two premises. The first is that, in order to adequately specify an interface, a designer must consider the inputs, outputs, and states of the system for which the interface is being designed. In this context, inputs refer to user-to-system communications, as mediated through buttons, keyboards, etc. Outputs refer to system-to-user communications, as mediated by displays, or other feedback. States refer to discrete conditions, either real or conceptual, in which the system may be at a given time. The second premise is that good, clear diagrams play an essential part in designing complex systems. Given appropriate diagramming techniques, it is much easier to describe complex activities and procedures in diagrams than in text. A picture can be worth more than a thousand words, because it is concise, precise, and clear. It does not allow the sloppiness and possibilities for misinterpretation that are common in text specifications.