Robert DeMarco

Ambulatory monitoring of physiology and behavior utilizing the PDA platform

Training prepares civilian first responders and military personnel to handle the many aspects of their mission to the best of their capability. For training to be the most effective, it should be as realistic as possible and elicit the stress response. Stress, however, is not measurable by a simple variable or recording. A stress response measurement requires the collection of physiological, behavioral, neuropsychological, and self report variables simultaneously. These are most valid when recorded or documented in real-time to the stress itself. To facilitate the recording of a stress profile, a handheld computer platform (HP-IPAQ) was developed. The HP-IPAQ with the PocketPC operating system running LabVIEW software offers the best flexibility for the interfacing of sensors and physiological amplifiers. The interactive human interface allows for the collection of self-report and other neuropsychological assessments. To test system designs, civilian and military trainees participated in various scenarios. Our system for simultaneous data collection of physiological and behavioral variables shows promise for field applications.

Effects of a single green flash versus a white flash of light on saccadic oculomotor metrics

White light encompasses all wavelengths of the visible optical spectrum while variations of green light cover only a fraction. Saccades comprise a considerable portion of ocular activity and have been used for research in neurology, cognitive processing, reading, and weaponry design. The goal of this experiment was to study how different energies of light affect the saccadic oculomotor system. This was tested by white and green photic stimulation in eleven and eight subjects respectively as they visually attempted to locate a target. The subject was presented with a target: 15 degrees to either the right or left from the midline with no photic stimulus (control), 15 degrees to the right or left accompanied by a photic stimulus at: midline, 15 degrees to the left, or 15 degrees to the right. Data were collected using the Skalar infrared limbic tracking system and a custom LabVIEW program. Dynamics were quantified with a latency analysis and the time to acquire /spl plusmn/ one degree of the target analysis using MatLAB. Results show that an increase in latency occurs during target location accompanied by a photic stimulus compared to target location accompanied by no photic stimulus, and that green light has a more robust effect on saccadic metrics than white light.

The dynamics of convergence insufficiency

Many people are hindered by vision dysfunctions. One of the most prominent vergence dysfunctions in society is convergence insufficiency (CI) affecting 7% of the population. This study inspects the dynamics of convergence movements in both CI and normal binocular vergence subjects. Two stimulus types, a four degree and six degree step, were presented to an subjects. The goal was to determine if the dynamics of CI subjects were different compared to subjects with normal binocular vergence. Using the main sequence analysis, data show the dynamics of CI subjects were in the normal range as those who had normal binocular vergence, but were on the lower end. This study shows the dynamics of Cl subjects, whom have not had vision therapy, are slower when initiating a convergence movement.

The use of a videogame for assessing sensory-motor and cognitive interference effects in humans

Light is a reliable visual distracter. Our research program is geared toward documenting the parameters by which different forms of light cause distraction in basic sensory-perception processes, motor abilities, and mental capabilities (sample classification, sample identification, trail markings short-term memory, etc.) Unlike the standardized assessment tests commonly used, we theorized that a videogame-type task would allow for multiple-trial measurements in tasks similar to what is assessed in the Wechsler Abbreviated Intelligence Scale. To determine if the commercial video game Police Trainer could be used as the videogame research tool we correlated measures of short-term memory (Wechsler Abbreviated Intelligence Scale) and sensory-motor processing (Grooved Pegboard) with tasks played In the game. We found that scores on specific tasks increased at different rates depending on the task complexity (simple visual-motor versus class identification or short-term memory). We concluded that the use of this videogame has utility as an active-assessment tool especially in studies where additional attention or cognitive load manipulations (such as visual or auditory distracters) are of primary interest We have now proceeded in implementing the video game into a light-distracting experiment. White light is presented. as the visual distracter from several angles, in reference to the games screen. As participants play the assigned tasks, an occasional 1 s flash of light is presented. Accuracy and latency to respond to the game-task is measured on the light-exposure trials versus the no-exposure trials. Behavioral reactions to the light stimuli were recorded using mini cameras in the room and on the game. Pilot data from the light exposure trials are presented.

Integrating biomedical engineering design into the freshman curriculum

A new freshman design course provides the opportunity to motivate incoming students with a contemporary problem. A design project, based on surgical robotics integrates mechanical, electrical and computer technologies with issues in medical practice.

Brief intermittent light stimulation disrupts saccadic oculomotor control

Purpose:  This study sought to determine the effect of very brief, single and multiple pulses of light on spatial and temporal aspects of saccadic eye movements.

Suppression: sound and light interference with targeting

Civilian law enforcement and military operations on urban terrain (MOUT) regularly enter into unknown situations where some unidentified subset of the populace may possess armaments that may be used against them. Ultimately, the most relevant test of the effectiveness of non-lethal energies in these situations is their ability to interfere with the targeting of those weapons on the friendly forces. It is also the test that offers the most immediate and tangible reward in the prevention of personnel injuries. Perceptual interference (e.g., light-induced flash blindness) or distractions from loud noises may contribute to targeting interference. How much do various energies or perceptual interventions actually interfere with targeting? We have devised a program of experimentation that allows for the pure and precise measurement of interference with the targeting process by any of a broad range of energies and stimuli. Our primary focus has been on sound and light interference with targeting, and experiments toward that purpose are described here. As expected, targeting accuracy decreased and targeting latency increased as the distance from fixation point to the target increased. The light flash interfered more with shots at more distant targets. Furthermore, as the angle between the fixation point and the flash increased, targeting latency increased but targeting accuracy was unaffected. Thus, light interference is greatest when the flash is not at the point of fixation. These studies suggest that foveal flashes are less disruptive than peripheral flashes, and that disruption increases as targeting task demands increase.

Blunt impact as deterrent: human approach-avoidance behaviors and other stress responses studied within a paintball gaming context

Blunt impact munitions are often used by civilian law enforcement and in military operations on urban terrain (MOUT) missions to dissuade individuals and groups from approaching valued assets. The use of blunt munitions (rubber-ball or sponge) is predicated on their effectiveness as aversive stimuli; the effectiveness is weighed against the risk of serious injury or death. However, little empirical evidence supports effectiveness. Here, we use a paintball gaming context to study the effects of blunt impact on performance and approach behaviors. Volunteers individually traversed a course in which targets offer the opportunity to gain for accuracy. While completing the targeting task, subjects were bombarded with paintballs, which progressively became more numerous and the impact more intense as the subjects neared goal locations. Initial data suggest that over 30 blunt impacts by paintballs delivered at 280 ft/sec over 30 to 100 ft are insufficient to overcome intrinsic and extrinsic approach motivations or impair targeting or advance performance in an overwhelming majority of subjects. Our apparent ceiling effect was surprising. A sub-comparison of the few subjects who stopped the game before the end with those who did not suggests that personality factors influence the effectiveness of blunt impact as a deterrent. While paintballs differ from traditional blunt impact munitions on a number of physical characteristics, impact that was sufficient to repeatedly bruise volunteers was not an effective deterrent.

360/spl deg/ sound and light interference targeting system

Sound and light stimuli elicit a considerable portion of human sensory activity and are utilized in psychophysics and neurology research. The engineering objective was to develop an automated system able to determine how sound and light interference affect the accuracy of the human targeting system in a three-dimensional space. This was achieved by development of a hardware and software system, sound and light interference targeting or SLIT, which presented the subject with a sound or light target, preceded by a sound or light interference. Sony/spl copy/ Xpl5d 4-way speakers presented sound interference and sound targeting. The Martin/spl reg/ MiniMAC Profile operated as a source of light interference, while a red laser served as a light target. Data were collected via the Ascension Flock of Birds tracking system and a custom National Instruments/spl reg/ LabVIEW/sup /spl trade// 7.0 program. The developed SLIT system enables the tracking of virtual shots from a fired simulation gun in 360 degrees of direction within a cylindrical environment.

Virtual targeting in three-dimensional space

Methods of measuring human gun shot accuracy include tracing real or virtual shots. Issues in utilizing real shots in shot accuracy experiments involve intermittently halting the study to restore the integrity of the apparatus and reduced safety due to fired projectiles. A videogame is an existing form of a virtual targeting system employing a light gun. However, this device limits users to two dimensions. A tracking system was developed to monitor gun movement and firing in three-dimensional space. Two test protocols examined the reliability of the system. The first tested the repeatability of the system while the second verified the accuracy of the system. For 25 targets, with n=9 for each target, the first test revealed average distances missed for x, y and z of 0.08 inches, 0.05 inches and 0.05 inches respectively. The second test determined a system error rate of 0.1 inches. The system provides the ability to determine shot accuracy and location, given specific targets.