Tactical checkpoint-hail/warn and suppress/stop

Distribution Statement A: Unclassified, Approved for Public Release


Tactical checkpoint- hail/warn and suppress/stop

Elizabeth Mezzacappa, Ph.D.; Charles Sheridan, MA; Robert DeMarco, MSBME; Kevin Tevis, BSME; Gladstone Reid, MSBME; Kenneth Short, Ph.D.; Nasir Jaffery, BSEE, MBA;

Gordon Cooke, MEME; John Riedener, MSSE ARDEC, Target Behavioral Response Laboratory, RDAR-QES-D, Building 3518

Picatinny Arsenal, New Jersey 07806

A. ABSTRACT Non-lethal weapons (NLWs) utility at checkpoints was investigated during daylight

conditions. Subjects drove on a course that simulated 1) a straight approach and 2) a serpentine approach to a checkpoint. Laser and multi-chromatic non-coherent (MCNC) light were evaluated for hailing and warning capabilities. Laser, MCNC light, and the windshield obscuration devices were evaluated for their suppression capabilities.

Results show that the natural response to the hail/warn devices was to continue driving straight ahead. When the light sources were used in conjunction with auditory instructions and signs, results show that there was no significant difference between the light sources and the subjects’ compliance rates. When instructions were given ahead of time as to the appropriate response to each of the light stimuli, fewer drivers followed the directions given in conjunction with the green laser. Suppression testing revealed that none of the stimuli was capable of inducing the driver to choose not to drive the serpentine course and none of the stimuli degraded navigational skills enough to cause contact or crashes with any barriers. There was a positive correlation between the degree of obscuration (number of paintball hits on the windshield) and the time to drive the serpentine course.

B. KEYWORDS non-lethal weapon, checkpoint, laser, light, driver behavior

C. NOMENCLATURE NLW non-lethal weapons MCNC multi-chromatic non-coherent GBD-III-C B.E. Meyers green beam designator N total number of cases Q(df) Cochran’s Q statistic with df degrees of freedom p p value, the probability of obtaining a test statistic that is at least as extreme as the one being reported, assuming that there are no differences between conditions F(v1, v2) F statistic with v1 and v2 degrees of freedom

http://en.wikipedia.org/wiki/Probability�

http://en.wikipedia.org/wiki/Test_statistic�



D. INTRODUCTION This paper reports the findings from four experimental investigations of the effectiveness of

tools and technologies that may be employed, or have been considered for employment, in military operations at tactical checkpoints in daylight conditions. The items under investigation included the B.E. Meyers green beam designator (GBD-III-C), high intensity red, green, and white light (Multi-Chromatic Non-Coherent (MCNC) light), and windshield obscuration. The laser and MCNC light were evaluated for their hailing and warning capabilities or, in other words, their ability to communicate a warning to a driver that is approaching a checkpoint. The laser, MCNC light, and the windshield obscuration were evaluated for their suppression capabilities (ability to suppress or stop a driver from proceeding towards the tactical checkpoint).

Effectiveness of devices for hailing and warning was measured by how reliably the stimuli

were perceived and understood, what percentage of the time the device caused compliance in a non-hostile driver, and time taken to comply with instructions. Effectiveness of devices for suppressing and stopping was measured by whether the stimuli were sufficiently averse to: (1) convince the driver to choose to stop, (2) impair the ability of driver to navigate or successfully operate the vehicle, or (3) impair the ability of the driver enough to cause a forced stop.

E. SETUP

1. Hail/Warn

The concrete test track was 250m in length and approximately 20m wide. Empty plastic traffic barriers were erected on the track to create three lanes on approach to the checkpoint. In this component, each participant acted as a non-hostile driver approaching a checkpoint. The participants started at the beginning of the route and traveled down a road toward the checkpoint. One of the four light conditions (laser or green, red, or white non-coherent light) was presented to the drivers en route. To maintain safe distances between the light devices and the human volunteers, the non-coherent light stimuli were delivered to subjects by commercially available spotlights mounted on barriers behind the channels and the laser source was mounted on a tripod at the Nominal Ocular Hazard Distance (47m) behind the hard barriers at the end of the track.

2. Suppress/Stop

The Suppress/Stop experiment used the same concrete test track in a different configuration. A wooden arch, traffic cones, and empty yellow plastic barriers were configured into a serpentine course that approached the checkpoint. In addition, a video camera set behind the barriers was used to record golf cart movements. Immediately after the subject drove over the sensor that was placed 10 meters before the wooden arch, one of the four conditions was triggered: green laser, non-coherent white light, paintball windshield obscurants, or a non-stimulus. Paintballs mounted in an array were used to simulate windshield obscurants for the



suppression of vehicles and were aimed in an attempt to completely cover the windshield of the vehicle.

F. Experimental Procedures

1. Subjects

All procedures were approved by the research ethics institutional review board prior to the study. Men and women (N=30) were recruited for the “Test Track: Driving with Lights and Sounds” and were paid $20 dollars per hour for the three to four hour experiment. Subjects were between 18 and 65 years old, healthy, and free of visual or auditory problems. After consenting, subjects were also carefully screened for visual and auditory deficiencies.

2. Experiment 1

Drivers initially drove in a straight path, traveling down the middle of the three-channel lane. Drivers were instructed not to attain any particular speed, but to drive as fast as they were comfortable with and to stop the cart after going through the lane. One of the four light conditions was presented 10m from the entrance of the channels. Drivers’ responses to the light condition were assessed under a 1.4-s laser exposures, or 1-s exposures of green, red, or white lights; the order of conditions was randomized and each light condition was presented twice. Because the stimuli order was randomized, time between exposures of the same stimuli were also randomized. The primary dependent variable was the percentage of subjects who stopped in response to each light condition. In addition, natural responses were observed, which included continuing straight through the middle channel, turning into the right channel, or turning into the left channel.

3. Experiment 2

Visual signs and auditory messages were paired with each of the light conditions. Subjects were instructed to follow the visual signs or auditory instructions (Right/Left/Stop) that they saw on the track, or to keep driving straight if they did not see or hear instructions. Drivers’ responses to the combined light condition (same as in Experiment 1) and the instruction sets presented while driving were investigated in a 4 (Light Condition) by 2 (Visual/Auditory) mixed model. Visual signs (Right/Left/Stop) were paired with each of the 4 light conditions from Experiment 1. Computer-controlled flip-up signs were presented while subjects were driving. Similarly, auditory messages (Right/Left/Stop) were paired with each of the 4 light conditions from Experiment 1. Loudspeakers broadcasted messages while subjects were driving. Sounds were kept below the safety threshold of 85dB, but were loud enough to be heard clearly in the cart, as verified each day using calibrated sound meters. The order of conditions was randomized and subjects experienced each condition twice. Again, because the stimuli order was randomized, the time between exposures of the same stimuli was randomized. The primary dependent variable was rates of subjects who complied in response to each stimulus. Light



condition and instruction conditions were compared for the rates of compliance. Thus if we assume people do not comply with messages that they do not understand, the resulting data reflects an understanding of the hail/warning communication.

4. Experiment 3

Drivers in this experiment utilized all three of the channels on the test track. The stimuli presented were a 1.4-s laser exposure or a 1-s exposure of green, red, or white light. However, for this experiment, subjects were informed ahead of time of what to do when presented with each stimulus. Instructions were to “Take Right Channel” when presented with white light, “Take Left Channel” when presented with green light (laser or non-coherent), or “Stop” when presented with a red light. The drivers were instructed to choose the middle lane in the absence of instruction, not to attain any particular speed but to drive as fast as they were comfortable with and to stop the cart after going through the lane. The order of conditions was again randomized and subjects experienced each condition twice. The primary dependent variable was the number of subjects who complied in response to each stimulus. Assuming that drivers do not follow instructions in situations where they do not perceive the stimuli, comparisons of driver’s reactions to the different stimuli will shed light on their relative perceptibility. As suggested in the introductory sections, perceptibility is a critical characteristic of hailing and warning technologies.

5. Experiment 4

In the Suppression component, subjects were exposed to 1.4-s laser, bright white light, or paintball obscurant stimuli prior to driving a serpentine course. The subject was exposed to each stimulus twice as well as a non-stimulus condition twice. All conditions were placed in random order. It was expected that the stimuli would degrade the ability to drive and degrade the ability to navigate the serpentine course.

Using the non-stimulus runs as a baseline, the suppressive effects of laser, non-coherent white light, and obscurant were compared. The primary dependent variables were whether or not the subject successfully reached the end of the serpentine course, the number of contacts with (bumps against) the yellow plastic barriers, velocity after application of stimuli, and time to complete the serpentine course. Effectiveness of the stimuli was assessed primarily through successful suppression of approach: inability to navigate car, stop on barriers, and willful stopping of vehicle.

G. RESULTS AND DISCUSSION

Behavioral data (entry into a channel or compliance with instruction) were analyzed with the Cochran’s Q test, a procedure appropriate in experiments involving repeated measures where the dependent variable can take on only two values (e.g., “entry or no entry” or “compliance or no compliance”). Time-based data (latency, time to complete course, or time from stimulus presentation to entry to course) were analyzed using a repeated measures within-subject design



General Linear Model regression using the baseline as the comparison condition. Spearman’s rho was used for non-parametric correlations.

1. Experiment 1

The response data for Experiment 1 were analyzed to examine the relationship among the type of light stimuli (green laser; green, white, or red non-coherent light) and driving response. Driving response was recorded as continuing straight through center channel, turning to drive through the right channel, or turning to drive through the left channel. No subjects stopped the vehicle in response to any stimuli.

The omnibus Q statistic indicated that there was a significant difference among the conditions of the experiment (Q(23) = 111.838, p<.0001). Post-hoc analyses did not reveal significant differences among the responses to any of the stimuli in either trial. The overall difference among conditions appears to be driven by the modal response to all conditions, which was to continue to drive straight through the center channel (61% on Trial 1, 56% on Trial 2). The results suggest that the typical response to all the stimuli is to continue on course. More importantly, they demonstrate that drivers are highly unlikely to stop in response to light stimuli without specific instructions to do so. Results from the correlation analyses did not reveal any association between ambient light and choice of channel.

Conclusion Experiment 1: Drivers are not likely to stop in response to lights without being clearly instructed to do so; the natural response is to continue on course. Warfighters should not expect that non-belligerent drivers will automatically know to stop in response to lights at checkpoints.

2. Experiment 2

The compliance data for Experiment 2 were analyzed to examine the relationships among type of stimuli (no stimulus; green laser; green, white, or red non-coherent light) and compliance with instruction (Figure 1). Sub-analyses looked at the compliance under visually-presented instructions versus audio instructions and trial for each stimulus.

The omnibus Q statistic indicated that there was a significant difference in compliance behavior among the conditions (Q(19) = 41.50, p<.0001). Post-hoc analyses of audio trials reveal that this difference was driven primarily by differences in compliance between the first and second audio instruction trial—regardless of associated light condition (Q(9) = 23.184, p<.006)—where first audio presentations of instructions were less likely to elicit compliance than second presentations. What makes this an even more important finding is that these subjects were aware that the use of auditory signals would be used during the experimentation, yet performance was not optimum on the first case. In an operational situation, where the driver of a vehicle would not be expecting an auditory signal, we might expect even lower performance levels on behalf of the driver during initial signaling. Analyses comparing compliance under different light conditions within the same mode of instruction and trial did not reveal any



differences. Correlation analyses did not reveal any associations between ambient light data and compliance with instructions.

These results indicate that there were no differences in the hailing and warning capabilities among the different light conditions. That is, none of the light conditions proved significantly better than any of the other light conditions with regards to rates of compliance with visual and audio instructions.

Conclusion Experiment 2: Drivers become better at understanding and then complying with instructions after repeated practice and experience at checkpoints. Therefore, Warfighters should expect that at a recently established or hasty checkpoint, drivers may not understand instructions and be unsure of what to do to comply. Non-compliance at a new checkpoint is less likely to signal hostile intent than at an older checkpoint. The converse also may be proposed - the longer a checkpoint has been in existence, the more likely that a non-compliant car contains hostile intent. In addition, escalation of force guidelines can be customized based on age of checkpoint, with longer distances assigned to relatively older checkpoints.

Figure 1. Percentage of subjects who complied under each experimental light stimuli conditions by instruction modality



3. Experiment 3

The compliance data for Experiment 3 were analyzed to examine the relationship between type of light (green laser; green, white, or red non-coherent light) and compliance to pre-instruction (Figure 2). The omnibus Q statistic indicated that there was a significant difference in compliance behavior among the condition (Q(7) = 27.606, p< .0001). These results were driven by a difference in compliance among stimuli both in the first trial (Q(3) = 15.00, p<.005) and in the second trial (Q(3) = 9.973, p<.02). The adjusted alpha was .025. The lowest rate of compliance was found in response to laser presentation. These results indicate that, compared with the other stimuli, subjects had more trouble seeing the laser light. Correlation analyses revealed a significant negative correlation between ambient light measures and compliance on both the first and second presentations of laser stimuli (Spearman’s rho= -.383, p<.05; Spearman’s rho= -.401, p<.05). The results indicate that the dimmer the light (the lower the ambient light levels), the easier to see the laser and comply with pre-instructions. At ambient light levels that were lower/dimmer than 14800 lux, there was 100% compliance (Figure 3).

Conclusion Experiment 3: In daylight laser light devices are more difficult to see than bright flashlights. In the daylight, bright flashlights are more effective than lasers for hailing and warning. Warfighters should avoid using lasers for hailing and warning drivers at checkpoints during these hours.

Figure 2. Number of pre-instructed persons who complied under each experimental light conditions



Figure 3. Compliance/non-compliance by level of ambient light.

4. Experiment 4

The data for Experiment 4 were analyzed using the repeated measures General Linear Model regression with stimuli (no stimuli, laser, bright white light, or obscurant paintball) and trial (first or second) as the independent variables. In one set of analyses, the dependent variable was time to complete the entire suppression course. In a second set of analyses, the dependent variable was the drive time from initiation of the stimuli to serpentine course entry. No subject hit the barrier on any trials. There were no significant effects of stimulus presentation on times to drive through serpentine course or times to drive from point of stimulus presentation to entry into the serpentine course. There was a significant effect of trial such that the second trial time through the serpentine course was significantly faster than the first (F(1, 29)=35.00, p<.0001). That is, while there were no significant differences in times through the serpentine course that were dependent on what stimulus was presented, subjects drove faster through the serpentine course



on later trials. Moreover, there were no relationships between ambient light measures and either time through course or time to entry of the serpentine course.

While there were no differences among the stimuli, finer analyses were carried out to examine the obscuration effects of paintball hits. In the first paintball trial, windshields were hit with a mean of 32.57 + 11.92 paintballs. In the second paintball trial, windshields were hit with a mean of 28.63 + 10.49 paintballs. Correlation analyses were performed to examine the relationship between number of paintballs on the windshield and time to complete the suppression course. There was a significantly large positive correlation between number of paintball hits and time to complete the course (First Trial, r = .58, p =.001 (Figure 4); Second Trial, r = .578, p=.001). These results indicate that the more paintballs that were on the windshield the slower the drivers went through the serpentine course, presumably because of the greater difficulty in seeing and navigating.

Conclusions from Experiment 4 : In the daytime and at distances required for safety reasons, the data indicate that that lasers are largely ineffective in suppressing drivers approaching checkpoints. None of the stimuli caused a crash or made drivers stop instinctively or intentionally. Warfighters should regard, with extreme caution, claims that any particular device will cause drivers to immediately stop. Windshield obscurants, however, do appear to be the most promising avenue of further research for suppressive effectiveness.

Figure 4. Time to complete suppression course by number of paintball hits to windshield.



H. THE WAY FORWARD

Making an impact on driver perceptions is the key to effectiveness of non-lethal weapons at entry control points. A non-lethal system that is both perceptible and understandable acts as a behavioral screen and can aid the Warfighter in distinguishing between non-hostile and hostile intent. That is, if the non-hostile driver can perceive and understand the hailing or warning device and the instructions, he or she will comply under typical circumstances. If a hostile driver can perceive and understand the hailing or warning device and instructions, he or she will not comply under typical circumstances. Non-lethal weapons that cannot be seen, heard, or understood are incapable of revealing hostile or non-hostile intent. If drivers cannot perceive the hailing or warning device or the instructions, compliance is unlikely, even by innocent persons that are highly motivated to comply. Non-lethal weapons that cannot be seen, heard, or understood will fail to induce non-hostiles to comply with Warfighter instructions. In contrast, taking away perception (specifically, taking away the ability for the driver to see) appears to be the most effective method for suppression with non-lethal weapons at entry control points. Non-lethal weapons that operate on methods of obscuration warrant further investigation. In conclusion, based on these and other results from our laboratory, future developmental work on novel devices must include investigation of human perception, cognition, and behavior in response to non-lethal stimuli.



Figure 5. Percentage of subjects who complied under each experimental light stimuli conditions by instruction modality



Figure 6. Number of pre-instructed persons who complied under each experimental light conditions



Figure 7. Compliance/non-compliance by level of ambient light.



Figure 8. Time to complete suppression course by number of paintball hits to windshield.

Documents

Tactical checkpoint-hail/warn and suppress/stop