Comparison of Army Hand and Arm Signals to a Covert 

Tactile Communication System in a Dynamic Environment 

by Rodger A. Pettitt, Elizabeth S. Redden, and Christian B. Carstens 

ARL-TR-3838 August 2006 

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Army Research Laboratory 

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ARL-TR-3838 August 2006 

Comparison of Army Hand and Arm Signals to a Covert 

Tactile Communication System in a Dynamic Environment 

Rodger A. Pettitt, Elizabeth S. Redden, and Christian B. Carstens 

Human Research & Engineering Directorate, ARL 

Approved for public release; distribution is unlimited.
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 Comparison of Army Hand and Arm Signals to a Covert Tactile Communication 

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 Rodger A. Pettitt, Elizabeth S. Redden, and Christian B. Carstens (all of ARL) 

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14. ABSTRACT 

This study was conducted jointly by the U.S. Army Research Laboratory and the University of Central Florida. The purpose of 

this experiment was to evaluate Soldiers’ abilities to interpret and respond to tactile commands compared to their abilities to

interpret and respond to standard visual hand and arm signals given from leaders in front of and behind them during movement. 

The tactile belt, developed by UCF, consists of eight tactors (tactile drivers) arranged equidistant around the Soldier’s waist. 

Individual or multiple tactors can be activated by an operator using a remote wireless control system. Infantry Soldiers, wearing 

their standard uniforms and body armor, negotiated a woodland individual movement technique (IMT) obstacle course while 

simulating a combat patrol. Tactile and visual hand and arm signals were sent to the Soldiers as they negotiated the course. 

The accuracy of signal interpretation and response times was recorded. The tactile signal patterns were intuitive and easy for

the Soldiers to understand; less than 10 minutes’ training was required for the Soldiers to become accurate in interpreting the

four tactile signals used during the experiment. Results demonstrated that Soldiers performing IMT were able to receive, 

interpret, and accurately respond to the tactile commands faster than when the information was passed by leaders in the front of 

a wedge formation and leaders in the back of a wedge formation using conventional hand and arm signals. Soldiers also 

commented that they were better able to focus more attention on negotiating obstacles and on area situational awareness when 

receiving tactile signals than when maintaining visual contact with their leaders in order to receive standard hand and arm 

signals. 

15. SUBJECT TERMS

 hand and arm signals; tactile communication system; tactile signals 

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 Rodger A. Pettitt 

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Standard Form 298 (Rev. 8/98) 

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iii 

Contents 

List of Figures v

List of Tables v

Executive Summary 1

1. Introduction 3

1.1 Statement of the Problem ................................................................................................3 

1.2 Objectives........................................................................................................................4 

2. Method 4

2.1 Overview .........................................................................................................................4 

2.2 Participants ......................................................................................................................4 

2.2.1 Pre-test Orientation and Volunteer Agreement ...................................................5 

2.2.2 Medical Review and Screening...........................................................................5 

2.2.3 Demographics......................................................................................................5 

2.3 Instruments and Apparatus..............................................................................................5 

2.3.1 Tactile System .....................................................................................................5 

2.3.2 IMT Course .........................................................................................................6 

2.3.3 Questionnaires .....................................................................................................8 

2.4 Procedures .......................................................................................................................8 

2.4.1 Training ...............................................................................................................8 

2.4.2 IMT Course Trials ...............................................................................................9 

2.5 Experimental Design .....................................................................................................10 

2.5.1 Independent Variable ........................................................................................10 

2.5.2 Dependent Variables .........................................................................................11 

2.6 Limitations.....................................................................................................................11 

3. Results 11

3.1 Demographics................................................................................................................11 

3.2 Training .........................................................................................................................11 

3.3 Woodland IMT Course Trials .......................................................................................12 

3.4 Soldier Questionnaire Responses ..................................................................................19 

4. Conclusions 20
iv 

5. Recommendations 21

6. References 22

Appendix A. UCF Contractor’s Report (with minimal correction) 23

Appendix B. IMT Course Layout 29

Appendix C. Soldier Questionnaire Results 31

Distribution List 37 
v 

List of Figures 

Figure 1. Distribution of mean response times (seconds)............................................................ 12 

Figure 2. Distribution of logarithmic mean response times (seconds). ....................................... 13 

Figure 3. Mean response times as a function of signal modality and obstable type.................... 16 

Figure 4. Failures to detect command as a function of signal modality and obstacle type. ........ 18 

Figure 5. Incorrect responses as a function of signal modality and obstacle type....................... 18 

Figure 6. Mean ratings of ease of signal detection. ..................................................................... 19 

Figure A-1. Photograph of a single tactor, model C2, manufactured by Engineering 

Acoustics, Inc........................................................................................................................ 24 

Figure A-2. Three tactile displays belt assemblies are shown above along with their tactor 

controller boxes (TCBs)........................................................................................................ 24 

List of Tables 

Table 1. Treatment assignments. ................................................................................................. 10 

Table 2. Mean response times...................................................................................................... 13 

Table 3. Mean logarithmic response times .................................................................................. 13 

Table 4. Ensuing comparisons, mean logarithmic response times. ............................................. 14 

Table 5. Correlations with mean logarithmic response times, n = 719 observations. ................. 14 

Table 6. Mean response times as a function of obstacle type...................................................... 14 

Table 7. Ensuing comparisons, mean logarithmic response times as a function of obstacle 

type........................................................................................................................................ 15 

Table 8. Mean and SD response times as a function of signal modality and obstacle type. ....... 15 

Table 9. Summary of repeated measures ANOVAs, logarithmic response times as a 

function of signal modality within each obstacle type.......................................................... 16 

Table 10. Ensuing comparisons, signal modalities within obstacle type..................................... 17 

Table 11. Proportion of correct responses. .................................................................................. 17
vi 

INTENTIONALLY LEFT BLANK
1 

Executive Summary 

This study was conducted by the U.S. Army Research Laboratory’s Human Research and 

Engineering Directorate with a state-of-the-art tactile prototype display developed by the 

University of Central Florida. The purpose of this experiment was to evaluate Soldiers’ abilities 

to interpret and respond to tactile commands compared to their abilities to interpret and respond 

to standard visual hand and arm signals given from leaders in front of and behind the Soldiers 

during movement. The evaluation was conducted with infantry Soldiers who negotiated a 

woodland individual movement technique (IMT) obstacle course while simulating a combat 

patrol. Tactile and visual hand and arm signals were sent to the Soldiers as they negotiated the 

course while wearing their standard uniforms and body armor. Accuracy of signal interpretation 

and response times were documented. 

The tactile signal patterns were found to be intuitive and easy for the Soldiers to understand. 

Very little training time (less than 10 minutes) was required for Soldiers to become accurate in 

interpreting the four tactile signals used during the experiment. Results demonstrated that 

Soldiers performing IMT were able to receive, interpret, and accurately respond to the tactile 

commands faster than when the information was passed by leaders in the front of a wedge 

formation and leaders in the back of a wedge formation using conventional hand and arm signals. 

Soldiers also commented they were better able to focus more attention on negotiating obstacles 

and on area situational awareness when receiving tactile signals than when maintaining visual 

contact with their leaders in order to receive standard hand and arm signals. 
2 

INTENTIONALLY LEFT BLANK
3 

1. Introduction 

1.1 Statement of the Problem 

The potential for information overload in dismounted Soldier organizations becomes greater as 

Army systems increase in complexity. The challenge for the dismounted infantryman is to monitor 

visual and auditory communication networks while maintaining situational awareness (SA) of his 

local environment. Concurrent performance of scanning and communication tasks has been shown 

to produce very high workload (Mitchell, Samms, Glumm, Krausman, Brelsford, & Garrett, 2004). 

One of the reasons why the Situational Understanding as an Enabler for the Unit of Action 

Maneuver Teams (SU) Army Technology Objective (ATO) was developed was to address the 

issues associated with information display for the dismounted Soldier. The ATO supports research 

focused on reducing the potential mental workload of Soldiers who often perform multiple tasks 

simultaneously. A primary theoretical basis for the ATO is Multiple Resource Theory (MRT) 

which appears to be a useful basis for designing interfaces for applications in which individuals 

perform several tasks at the same time (Wickens, 1991). 

Display interventions have been particularly effective in situations when individuals have multiple 

demands for attention. MRT suggests that distributing tasks and information across various 

sensory modalities might be an effective display intervention. MRT proposes that humans have a 

finite capacity for processing information (Wickens, 1991). Off loading some of the information 

to other modalities can reduce dual task interference, which should lead to more efficient 

processing and improve task-sharing performance (Sklar & Sarter, 1999). In situations when 

demands on audition and vision are high1, it may be beneficial to include the tactile communication modality for intra-squad communication. Recently, tactile displays have shown promise when 

used as communication systems for pilots and astronauts to aid in spatial orientation by providing 

directional cues (Gilliland & Schlegel, 1994; Jones & Nakamura, 2003), as navigational aids (van 

Erp, 2005; Elliott, Redden, Krausman, Carstens, & Pettitt, 2005), as target cues (Glumm, Kehring, 

& White, in process), and as alerts for display operators (Krausman, Elliott, Redden, & Petrov, 

2005). Tactile displays may have the capacity to communicate even more complex messages. 

Challenges are involved in conveying battlefield information to the dismounted Soldier in a 

manner that enhances his ability to manage the information and thus increase his or her SA. The 

research cited suggests that allocating information and tasks among different senses may lessen 

channel bottlenecks and processing limitations, thus enhancing the information management and 

situational understanding of Soldiers. With proper implementation, the use of tactile displays for 

the Soldier could reduce demands on and interference with the Soldiers’ visual and auditory 

 1

Such as a dismounted Soldier listening to sounds announcing the enemy’s approach while looking for signs of 

enemy ambush.
4 

channels, thereby improving overall performance. The present study is an investigation of the 

efficacy of translating infantry hand and arm signals into a vocabulary of tactile commands. The 

following issues were addressed: Can Soldiers easily distinguish one tactile command from 

another? Can they quickly learn a limited vocabulary of tactile signals? How well and how 

quickly can they understand and respond to tactile commands while performing individual 

movement techniques (IMT) in a dynamic environment? 

1.2 Objectives 

• Are the Soldiers able to interpret and respond to tactile commands as efficiently as they can 

interpret and respond to hand signal commands in a dynamic environment? 

• Does the use of the tactile system impair the ability of the Soldiers to complete the 

obstacles on the woodland IMT course? 

2. Method 

2.1 Overview 

The purpose of this experiment was to provide an evaluation of a covert tactile communication 

system. The system used in this experiment was designed by researchers at the University of 

Central Florida (UCF) to communicate a variety of commands corresponding to standard Army 

hand signals. Soldiers were given commands by hand and arm signals or by covert tactile 

signals while they moved through a woodland IMT course. Soldiers wore their fighting loads, 

including interceptor body armor (IBA) without ceramic insert plates, and carried simulated 

personal weapons (M4 carbines). After being trained to use the system, each Soldier completed 

the IMT course three times while receiving tactile signals, hand and arm signals from a leader in 

front of the Soldier, and hand and arm signals from a leader behind the Soldier. The systems 

were compared for objective performance data, data collector observations, and answers to 

Soldier questionnaires. 

2.2 Participants 

Thirty Soldiers from the Infantry Training Brigade (ITB), Fort Benning, Georgia, participated in 

the assessment. The assessment was conducted over a 3-day period. It was made clear that 

Soldier participation in the study was voluntary. To ensure the voluntary nature of participation, 

copies of the consent form were provided to all participating subjects who were then given an 

opportunity to review the assessment objectives. Their questions were answered by the 

investigators, and they were asked to sign consent forms indicating their informed voluntary 

consent to participate. The Soldiers were informed that if they chose not to participate, they 
5 

could convey that choice privately to the assessment manager who would have informed that 

Soldier’s unit supervisor, without elaboration, that the Soldier did not meet study criteria. Had 

any designated subject chosen not to participate in any of the exercises, the unit would have been 

asked to recruit another volunteer. All tasks used for this study were a normal part of the 

Soldier’s job. The Soldiers completed this assessment using the tactile system while wearing 

their Army combat uniform (ACU) and standard fighting load. They carried a training device 

simulating the M4 during the IMT course. 

2.2.1 Pre-test Orientation and Volunteer Agreement 

The Soldiers were given an orientation about the purpose of the study and their participation. 

They were briefed about the objectives and procedures for each exercise, as well as the 

equipment they were required to use throughout the investigation. They were also told how the 

results would be used and the benefits the military could expect from this investigation. Any 

questions the subjects had regarding the study were answered. In addition, a volunteer 

agreement affidavit was explained and its contents were verbally presented. The Soldiers were 

then given the volunteer agreement affidavit to read and sign, and they all signed. 

2.2.2 Medical Review and Screening 

At the outset of the assessment, the investigators asked the Soldiers if any of them had a medical 

profile or history that would jeopardize them if they participated in the study. Soldiers were also 

asked to complete a medical status form. 

2.2.3 Demographics 

Demographic data were taken for each Soldier. Data concerning their physical characteristics, 

infantry experience, and training were included in the demographic data form. 

2.3 Instruments and Apparatus 

2.3.1 Tactile System 

The tactile system used during this experiment was developed by the UCF under a Defense 

Advanced Research Projects Agency (DARPA) contract (number DAAE0703CL143). UCF 

assembled a team of scientists, product designers, builders, programmers, and Soldiers who 

employed their knowledge of human physiology and battlefield tactics to construct a tactile 

display system that is reliable and easy to use. This system is capable of remotely conveying 

covert signals, cues, and messages by touch. Each system consists of a tactile display worn 

around the waist with a receiver unit that was stowed in the cargo pockets of the Soldiers during 

negotiation of the obstacle course. The display itself consists of eight tactile drivers (tactors) that 

create a strong localized sensation on the body. The tactors can be activated individually, 

sequentially, or in groups to provide a specific sensation or to create unique patterns of vibration 
6 

analogous to standard Army hand signals that are used when Soldiers are in visual contact. The 

control unit receives wireless signals and converts them into recognizable patterns of vibration. 

A more detailed description of the tactile system is presented in the contractor’s report in 

appendix A. 

For this experiment, the system used a personal digital assistant (PDA) with programmed buttons 

to initiate transmission for four basic commands as tactile patterns designed to be analogous to 

standard Army hand signals. The four commands used in this experiment (attention, halt, move 

out, and rally) represent only a few of the many commands and types of information that can be 

conveyed by the system (see the contractor’s report in appendix A for a detailed description of 

the tactile signals). The tactile representations of these signals were designed in a collaborative 

effort of scientists at UCF and a consultant group of subject matter experts (SMEs) consisting of 

former U.S. servicemen. These sequences were then slightly modified in laboratory testing at 

UCF and developed for this field test. 

2.3.2 IMT Course 

The IMT course requires Soldiers to use most urban and non-urban tactical maneuvers and IMT. 

It requires Soldiers to execute a variety of individual movements and assume a variety of 

positions while maneuvering through, over, under, and around obstacles. The primary advantages 

of using this course rather than actual terrain are control, standardization, and repeatability. The 

obstacles were categorized according to the activity the Soldier was performing at the time he was 

given a command. The four obstacle types were patrolling, crawling, firing, and climbing. 

Soldiers initially walked through the course, and each obstacle and position was explained before 

the first record trial was run. In addition, all Soldiers completed one familiarization trial wearing 

their uniform, standard fighting load, and tactile belt and carrying their assigned weapon. 

Appendix B contains a sketch of the course. A description of each event and instructions for 

executing the event are provided next. 

• Starting Point. (Patrolling) The starting point is clearly marked with a white line that spans 

the width of both lanes on the course. The course requires the Soldier to begin in the 

upright standing position with his weapon held at “port arms”. On the command “go” from 

the data collector, the trial begins and the Soldier moves approximately 30 meters to 

obstacle A. Once the course is started, he follows his team leader at a distance of 

approximately 10 meters through the entire course, executing each obstacle along the way, 

until the end is reached. 

• Obstacle A, Pipe Crawl. (Crawling) The pipe is 6 m long and 1 m in diameter and is made 

of corrugated steel. It has a ridged surface, and Soldiers wear elbow and knee pads to 

avoid injury. The Soldier moves as quickly as possible to complete the obstacle without 

causing injury to himself or damage to his equipment. Once through the pipe crawl, the 

Soldier moves to obstacle B. 
7 

• Obstacle B, Zigzag. (Patrolling) The zigzag is 1.6 m tall, 14 m in length, and 

approximately 1 m in width. It consists of three turns (approximately 90 degrees each) 

within the lane. The framework is constructed of wood with mesh wire installed between 

the two lanes and on the outside framework of each lane. The zigzag requires the Soldier 

to proceed through the obstacle as quickly as possible without causing any injury to himself 

or damage to his equipment. Once through the zigzag, the Soldier moves around the first 

bend to obstacle C. 

• First Turn. (Patrolling) On the first turn, the Soldier follows a 180-degree bend in the 

course which ends at the 2-foot wall kneeling firing position. 

• Obstacle C, 2-foot Wall Kneeling Firing Position. (Firing) Upon entering the station, the 

Soldier assumes a kneeling supported firing position. Once completed, the Soldier moves 

to obstacle D. 

• Obstacle D, Mound. (Patrolling) The mound is approximately 10 m long, 2 m wide, and 

3 m tall with a 30-degree sloped incline and decline along the route of movement. The 

Soldier ascends and descends the mound and then moves to obstacle E. 

• Obstacle E, Prone Unsupported Firing Position Station. (Firing) The prone unsupported 

firing position station is 2 m long by 1 m wide. The Soldier enters the station and assumes 

a prone unsupported firing position. Once completed, the Soldier moves to obstacle F 

• Obstacle F, Low Crawl. (Crawling) The low crawl is 13 m long and 3 m wide with an 

overhead cover of mesh wire approximately 0.6 m off the ground. The Soldier completes 

the obstacle as quickly as possible using correct low crawl techniques. After completing 

the low crawl, the Soldier proceeds around the second turn to obstacle F. 

• Second Turn. (Patrolling) On the second turn, the Soldier follows a 180-degree bend in the 

course which ends at the combat roll. 

• Obstacle F, Combat Roll. (Firing) Each lane of the combat roll station is about 6 m long 

and 1 m wide. The Soldier hastily assumes the prone position immediately after entering 

the station. He then executes a full combat roll to the left or right, pushes off the ground 

using the butt stock of the weapon, executes a 3- to 5-second rush, and returns to the prone. 

The Soldier then executes a full combat roll to the left or right, pushes off the ground using 

the butt stock of the weapon, and moves to obstacle G. 

• Obstacle G, High Crawl. (Crawling) Each lane of the high crawl is 13 m long and 3 m 

wide with an overhead cover of mesh wire approximately 1 m off the ground. The Soldier 

moves as quickly as possible, using correct high crawl procedures, to negotiate the full 

length of the obstacle. Once through the high crawl, the Soldier moves to obstacle H. 

• Obstacle H, Kneeling Firing Position Station. (Firing) The kneeling firing position station 

provides a wooden support 2 m wide, 1 m tall, and 13 cm deep for the Soldier to support 
8 

the weapon against during target acquisition and engagement. Upon entering the station, 

the Soldier assumes a kneeling supported firing position. Once completed, the Soldier 

moves to obstacle I. 

• Obstacle I, High Wall. (Climbing) The high wall is made of wood, is 1.4 m tall, 1.8 m 

wide, and 13 cm deep. The Soldier climbs over the obstacle without causing any personal 

injury or damaging equipment while maintaining control of the weapon at all times. Once 

the high wall is cleared, the Soldier moves to obstacle J. 

• Obstacle J, Prone Supported Firing Position Station. (Firing) The prone firing position 

station is 2 m long by 1 m wide with sandbags provided to support the weapon. The 

Soldier enters the station and assumes a prone supported firing position. Once completed, 

the Soldier moves to obstacle K. 

• Obstacle K, Urban Wall Window Kneeling Firing Position. (Firing) The Urban wall 

replicates several urban obstacles. Upon reaching the wall, the Soldier assumes a kneeling 

firing position at the opening that represents a window. Once completed, the Soldier 

proceeds to obstacle L. 

• Obstacle L, Urban Wall Ladder. (Climbing) At Obstacle L, the Soldier climbs a ladder 

over the top of the urban wall and climbs down the ladder on the opposite side of the wall 

and moves to obstacle M. 

• Obstacle M, Stairs. (Climbing) The stairs are made of wood. Five steps lead up to a 

platform and five steps lead down. Once the stairs are completed, the Soldier moves to the 

end point. 

• End Point. (Patrolling) The Soldier moves approximately 30 meters and completes the 

IMT course. 

2.3.3 Questionnaires 

Questionnaires were designed to elicit Soldiers’ opinions about their performance and 

experiences for each iteration while they wear the tactile system. The questionnaires were 

designed to enable Soldiers to rate the ease of receiving and understanding visual and tactile 

communications while negotiating obstacles and their overall experience with the tactile system. 

Questionnaires were administered to each Soldier at the completion of each iteration. 

2.4 Procedures 

2.4.1 Training 

Before beginning training, the Soldiers received a roster number, which was used to identify them 

throughout the assessment. A UCF representative presented a course on the use and fit of the 
9 

tactile system and the tactile signal interpretation. Approximately 7 to 10 minutes of 

familiarization with the tactile system were given to Soldiers before they completed the obstacle 

course. Familiarization for every Soldier consisted of approximately 17 repetitions of the four 

tactile signals: three repetitions without fighting loads, four times with fighting loads, and two 

times each with fighting loads in the kneeling, prone, combat roll, walk, and run positions/actions. 

Just before the Soldier started the obstacle course, a researcher presented and reviewed each tactile 

signal again to ensure that the Soldier understood the signals. A representative from the U.S. 

Army Research Laboratory’s Human Research and Engineering Directorate also presented a 

refresher course on hand and arm signals. Soldiers were trained until they were 100% accurate on 

all signals. Each Soldier was retested on all the signals before each obstacle course iteration to 

ensure that learning decay had not taken place. Upon completion of the training, the Soldiers were 

given a questionnaire designed to assess their perception of the training adequacy. 

The requested Soldiers were in a military occupational specialty (MOS) that requires performance 

of mobility and portability maneuvers (movement to contact and assault maneuvers), and 

movement as a dismounted element that is associated with their profession (Department of Army, 

1999). No specialized experience was required. However, the Soldiers were shown how to 

negotiate the IMT course safely and were trained in specific procedures as required. Additionally, 

the Soldiers walked through the course at a slow speed to better familiarize them with the course, 

as well as reduce Soldier risk during actual course execution. Before the record trials were run, 

Soldiers participated in a practice trial on the obstacle course, during which, hand and arm signals 

and tactile signals were sent. 

2.4.2 IMT Course Trials 

Soldiers completed three iterations of the IMT course according to the matrix shown in table 1. 

During each iteration, Soldiers wore the tactile system and were led through the IMT course by a 

team leader and were followed by a squad leader. These positions are consistent with a Soldier 

acting as a member of a squad in a wedge formation. The team leader was designated to 

communicate visual hand and arm signals from the front and the squad leader from the rear. 

Tactile commands were communicated to the Soldier by a controller operating the control unit. 

The controller operating the control unit stayed within 10 to 15 meters of the Soldier as he 

moved through the course. A data collector recorded the time from the command’s initiation 

until it was acknowledged by the Soldier and whether the correct response was given. Before 

negotiating the course, Soldiers were briefed that signals could be received at any point during 

the course from the team leader (front), squad leader (rear), or through the tactile belt. Soldiers 

were instructed to tell the data collector the meaning of the signal when a signal was received 

visually or tactilely. Soldiers were also instructed to maintain a 10- to 15-meter interval from the 

team leader while moving through the course. As a visual distraction task, Soldiers were told to 

look for Special Forces, Airborne, and Ranger tabs which were placed at various locations on the 

course and to scan the woods for targets. At the completion of each course trial, a subjective 
10 

questionnaire was administered. In addition, data collector observations were recorded for each 

trial. 

When Soldiers were not running the IMT course, they were kept out of view of the course so that 

they did not learn the sequence and location of signals. 

Table 1. Treatment assignments. 

Obstacle 

Activity 

Type Signal 

Communication 

Condition 

Pipe Crawl Crawl HALT Tactile 

1st Turn Patrol ATTENTION Rear H & A 

Prone Unsupported Fire ATTENTION Front H & A 

2nd Turn Patrol MOVE OUT Tactile 

High Crawl Crawl RALLY Rear H & A 

High Wall Climb MOVE OUT Tactile 

Urban Window Fire HALT Rear H & A 

Stairs Climb RALLY Front H & A 

Iteration 2 

Obstacle 

Activity 

Type Signal 

Communication 

Condition 

Zigzag Patrol ATTENTION Front H & A 

2ft Wall Kneel Fire ATTENTION Rear H & A 

Low Crawl Crawl RALLY Front H & A 

Combat Roll Fire HALT Tactile 

High Crawl Crawl HALT Rear H & A 

High Wall Climb RALLY Rear H & A 

Urban Wall Climb MOVE OUT Front H & A 

End Patrol ATTENTION Tactile 

Iteration 3 

Obstacle 

Activity 

Type Signal 

Communication 

Condition 

Start Point Patrol MOVE OUT Front H & A 

Pipe Crawl Crawl HALT Front H & A 

Hill Patrol MOVE OUT Rear H & A 

Low Crawl Crawl RALLY Tactile 

Kneeling Fire HALT Front H & A 

Prone Supported Fire ATTENTION Tactile 

Urban Wall Climb RALLY Tactile 

Stairs Climb MOVE OUT Rear H & A 

2.5 Experimental Design 

2.5.1 Independent Variable 

The independent variables were the signal modality (tactile signals, hand and arm signals from 

the front, and hand and arm signals from the rear) and the obstacle type (patrol, fire, crawl, or 

climb). 
11 

2.5.2 Dependent Variables 

The dependent variables for the IMT trials were 

• Data collectors’ observations of the Soldiers completing the IMT course. 

• Whether the Soldier responded to the command. 

• Whether the Soldier made the correct response to each command. 

• Time from the initiation of command to the Soldiers’ response to the command. 

• Soldiers’ overall ratings of the IMT course negotiation with the tactile system. 

2.6 Limitations 

The IMT course made it much easier to see the hand and arm signals than if the experiment had 

been conducted in wooded terrain where vegetation and terrain features could have masked the 

leaders more. However, the IMT course made conditions identical for each run. Also the 

experiment was conducted only during daylight conditions, which made it easier to see hand and 

arm signals than if the experiment had been conducted at night. The fact that the Soldiers wore 

IBA without ceramic insert plates could have influenced the ease of tactile communication; the 

plates may have interfered with tactile signal detection and interpretation. 

3. Results 

3.1 Demographics 

Thirty enlisted personnel in the ranks of E-1 through E-4 served as the experimentation Soldiers. 

All the Soldiers had an infantry MOS of 11. Their average time in service was 10 months. 

Soldiers’ heights ranged from the 8th to the 96th percentile and their weights ranged from the 1st 

to the 99th percentile. Detailed demographic results are provided in appendix C. 

3.2 Training 

Very little time was required to train the Soldiers to become accurate in interpreting the tactile 

signals and for refresher training on the hand and arm signals. Soldiers became proficient after 

approximately 7 to 10 minutes of individual training on the tactile signals and rated them as 

easier to learn than the hand and arm signals. All the Soldiers rated the training as being “good” 

to “extremely good”. Detailed training questionnaire results are included in appendix C. 
12 

3.3 Woodland IMT Course Trials 

Because of a floor effect in the time to respond to signals (the lowest possible time is 0.1 second), 

the data are highly skewed. This is illustrated in the average response times for all conditions 

combined as shown in figure 1. 

Analysis of variance (ANOVA) is based on the assumption that the data are approximately 

normally distributed, i.e., the distribution would look like a bell curve. When the data set is 

markedly skewed, it is common practice to do a logarithmic (log10) transformation to achieve a 

better approximation of normality. Figure 2 shows the distribution of the mean response times 

after the logarithmic transformation. It is clear that the logarithmic transformation was 

successful in producing a better approximation of a normal distribution. 

All ANOVAs and ensuing comparisons reported here were done with the logarithmic transformed 

data. However, when the statistics were run on the logarithmic transformed data and the untransformed data, the results were virtually identical in all cases. 

0%

5%

10%

15%

20%

25%

30%

35%

40%

<2 2-

2.99

3-

3.99

4-

4.99

5-

5.99

6-

6.99

7-

7.99

8-

8.99

9-

9.99

>9.99

sec

% Figure 1. Distribution of mean response times (seconds). 

Tables 2 and 3 show the mean response times across the three IMT iterations for the three 

methods of signaling. For purposes of analysis, failures to respond to signals were coded as 

response times of 20 seconds. 
13 

0%

5%

10%

15%

20%

25%

<.2 .2-

.29

.3-

.39

.4-

.49

.5-

.59

.6-

.69

.7-

.79

.8-

.89

.9-

.99

>.99

log10sec

%

Figure 2. Distribution of logarithmic mean response times (seconds). 

Table 2. Mean response times. 

Signal Modality Mean SD 

Hand signals -- rear 4.65 2.02 

Hand signals -- front 2.93 1.17 

Tactile signals 1.81 0.64 

SD = standard deviation 

Table 3. Mean logarithmic response times 

Signal Modality Mean SD 

Hand signals -- rear 0.63 0.17 

Hand signals -- front 0.44 0.14 

Tactile signals 0.24 0.12 

A repeated measures ANOVA was performed on the logarithmic transformed scores (see table 3). 

This analysis yielded a statistically significant effect for signal modality: F(2,58) = 80.3, p < 0.001, 

ηp

2

 = 0.735. Ensuing pairwise comparisons were done with Holm’s Sequential Bonferroni 

correction to control for family-wise error (see table 4). These ensuing comparisons show that 

response times were significantly faster with the tactile signals than with the hand signals and that 

response times were significantly faster when the hand signals came from the Soldier’s front rather 

than the rear. 
14 

Table 4. Ensuing comparisons, mean logarithmic response times. 

Comparison df t Obtained p Required p 

Rear versus Front 29 5.92 < .001* 0.05 

Rear versus Tactile 29 12.03 < .001* 0.0167 

Front versus Tactile 29 7.25 < .001* 0.025 

*p < .05, two-tailed

In order to examine the possibility that extraneous variables might have influenced response 

latency, logarithmic response times were correlated with the following variables: 

• Iteration: 1, 2, or 3 

• Order of signal within iterations: 1 through 8 

• Type of Obstacle: Fire, Patrol, Crawl, or Climb 

• Command: Halt, Attention, Move out, Rally 

• Signal modality: Hand – rear, Hand – front, Tactile 

Table 5 shows the bivariate correlations between each of these variables and logarithmic 

response times. 

Table 5. Correlations with mean logarithmic response times, n = 719 observations. 

Bivariate Correlations Obstacle Partialed Out 

Variable r p r p 

Iteration 0.01 0.87 - - 

Order 0.13 < .001 0.05 0.138 

Obstacle 0.22 < .001 - - 

Command 0.17 < .001 0.02 0.522 

Modality 0.46 < .001 0.47 < .001 

In addition to “signal modality,” the extraneous variables of “order,” “obstacle,” and “command” 

each had small but statistically significant correlations with logarithmic response time. Of these 

extraneous variables, “obstacle type” had the highest correlation with response latencies. The 

effect of obstacle type is shown in table 6. A repeated measures ANOVA indicates that there 

was a statistically significant difference in logarithmic response latencies among the four types 

of obstacles: F(3,87) = 12.8, p < 0.001, ηp

2

 = 0.307. 

Table 6. Mean response times as a function of obstacle type. 

Obstacle Type Mean SD 

Firing 2.38 0.84 

Patrolling 2.76 1.10 

Crawling 3.25 2.40 

Climbing 4.13 1.84 
15 

Ensuing pairwise comparisons (table 7) indicate that responses were slowest when the Soldiers 

were engaged in climbing events and that when the Soldier was in a stable firing position, he 

responded faster than when he was crawling or climbing. 

Table 7. Ensuing comparisons, mean logarithmic response times as a function of obstacle type. 

Comparison df t Obtained p Required p 

Crawl versus Fire 29 2.70 0.012* 0.0167 

Crawl versus Climb 29 2.80 0.009* 0.0125 

Crawl versus Patrol 29 0.95 0.348 0.05 

Fire versus Climb 29 6.49 < .001* 0.0083 

Fire versus Patrol 29 1.73 0.094 0.025 

Climb versus Patrol 29 4.60 < .001* 0.01 

*p < .05, two-tailed

The statistical technique of partial correlation can be used to interpret the positive correlations 

between logarithmic response times and the “order” and “command” variables. In a partial 

correlation, two variables are correlated (“order” and “time” or “command” and “time”) while 

we control for the effects of a third variable (“obstacle type”). An analysis of partial correlations 

indicates that the small but statistically significant relationships between logarithmic response 

times and the “order” and “command” variables are artifacts of the “obstacle type” variable. As 

shown in table 5, when “obstacle type” is statistically controlled or partialed out, the correlations 

between logarithmic response times and the “order” and “command” variables become nonsignificant. Order correlated with logarithmic times only because the climbing obstacles, which 

had longer latencies, come at the end of the IMT course. Partialing “obstacle” has no substantial 

impact on the correlation between logarithmic response times and “signal modality”. 

The next analysis examines the effect of “signal modality” within each of the four obstacle types. 

Table 8 shows the mean response latencies for the three “signal modalities” as a function of 

obstacle type. These means are illustrated in figure 3. This graph shows that the type of obstacle 

influenced response latencies for hand signals but not for tactile signals. As shown in table 9, 

“signal modality” had a statistically significant effect within each obstacle type. 

Table 8. Mean and standard deviation response times as a function of signal modality and obstacle type. 

Modality Fire Walk Crawl Climb 

Tactile 1.84(1.64) 1.84(0.80) 1.76(0.61) 1.80(0.77) 

Front 1.63(0.71) 2.27(0.74) 3.93(3.94) 3.89(1.75) 

Rear 3.66(1.89) 4.17(2.97) 4.07(3.25) 6.71(4.91) 
16 

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

Fire Walk Crawl Climb

Time (sec)

Tactile

Front

Rear

Figure 3. Mean response times as a function of signal modality and obstable type. 

Table 9. Summary of repeated measures ANOVAs, logarithmic response times as a 

function of signal modality within each obstacle type. 

Obstacle F df p ηp

2

Fire 31.8 2,58 < .001 0.523 

Patrol 22.4 2,58 < .001 0.436 

Crawl 30.6 2,58 < .001 0.513 

Climb 55.7 2,58 < .001 0.658 

Table 10 shows the results of ensuing pairwise comparisons of the three signal modalities within 

each obstacle type. Soldiers responded significantly faster to tactile signals than to hand signals 

from the rear in all obstacle conditions. Responses to tactile signals were significantly faster 

than responses to front hand signals for all obstacle types except “firing positions”. Front hand 

signals produced faster response than rear hand signals in all obstacles except “crawling” events. 

Table 11 shows the proportion of correct and incorrect Soldier responses to the signals as a 

function of signal modality. There was a significant difference in correct responses among the 

three modalities: χ2 (df=2) = 24.0, p < 0.001. Further analysis shows that the correct response 

rate was lower in the “hand-rear” condition relative to the other two signal conditions: χ

2

 (df=1) 

= 20.6, p < 0.001. There was no significant difference in the proportion of correct responses 

between the “hand-front” and “tactile” conditions. 
17 

Table 10. Ensuing comparisons, signal modalities within obstacle type. 

Table 11. Proportion of correct responses. 

Tactile 

(percent) 

Front 

(percent) 

Rear 

(percent) 

Correct 95.3 98.3 87.8 

Incorrect 4.7 1.7 12.2 

An additional analysis of the missed responses was conducted to separate them into “failures to 

detect” the commands versus “incorrect responses” to detected commands. Figure 4 shows the 

number of failures to detect commands, of a total of 720 commands, by “signal modality” and 

“obstacle”. There was a significant difference in the number of “failures to detect” among the 

three signal modalities: χ2 (df=2) = 18.5, p < 0.01. There was also a significant difference in the 

number of “failures to detect” among the four obstacle types: χ2 (df=3) = 7.82, p < 0.05. The 

greatest number of “failures to detect” came with the “hand signals from the rear” and on the 

“climbing obstacles”. 

The number of incorrect responses to detected commands is illustrated in figure 5. There was no 

significant difference in incorrect responses for either the “signal modalities” (χ

2

 (df=2) = 5.39) 

or the “obstacle types” (χ

2

 (df=3) = 5.54). There was a non-significant trend for the greatest 

number of incorrect responses occurring with the “hand signals from the rear” and “on the 

climbing obstacles”. 

Obstacle Comparison df t Obtained p Required p 

Tactile versus Front 29 0.55 0.585 0.05 

Fire Tactile versus Rear 29 6.19 <.001* 0.025 

Front versus Rear 29 7.40 <.001* 0.0167 

Tactile versus Front 29 2.72 0.011* 0.05 

Patrol Tactile versus Rear 29 6.39 <.001* 0.0167 

Front versus Rear 29 3.83 0.001* 0.025 

Tactile versus Front 29 5.51 0.001* 0.025 

Crawl Tactile versus Rear 29 7.29 0.001* 0.0167 

Front versus Rear 29 1.09 0.383 0.05 

Tactile versus Front 29 9.11 0.001* 0.025 

Climb Tactile versus Rear 29 9.18 0.001* 0.0167 

Front versus Rear 29 3.33 .002* 0.05 
18 

0

1

2

3

4

5

6

7

8

9

Fire Patrol Crawl Climb

# no detect

Tactile

Front

Rear

Figure 4. Failures to detect command as a function of signal modality and obstacle type. 

0

1

2

3

4

Fire Patrol Crawl Climb

# incorrect

Tactile

Front

Rear

Figure 5. Incorrect responses as a function of signal modality and obstacle type. 
19 

3.4 Soldier Questionnaire Responses 

Soldiers rated the “hand signals” and the “tactile signals” as being very easy to learn. Soldiers 

rated the “tactile commands” and the “front hand commands” as very easy to detect and 

interpret. One Soldier stated that the tactile system seemed to become progressively easier to 

interpret as the iterations progressed. By the third iteration, he stated that the tactile belt was 

easier and quicker to understand than clearly visible hand and arm signals. The “rear hand 

signals” were rated as being more difficult to detect and interpret. 

Figure 6 shows the mean ratings for detecting specific signals at specific obstacle types 

(1 = ”extremely difficult”; 7 = “extremely easy”). For each obstacle type, Soldiers rated the 

“rear hand signals” as being more difficult to detect and interpret than the “tactile signals” or the 

“front hand signals”. 

0

1

2

3

4

5

6

7

Fire Patrol Crawl Climb

Mean rating

Tactile

Front

Rear

Figure 6. Mean ratings of ease of signal detection. 

Soldiers indicated that the tactile system allowed them to focus more attention on negotiating 

obstacles and that it would be useful in tactical situations in which they would need to focus on 

other tasks such as security. Soldiers commented that it was very difficult to receive a visual 

hand and arm signal at certain points on the course where their full attention was given to 

negotiating the obstacle or when they could not maintain visual contact with the leaders. 

Soldiers stated they knew immediately when they received a tactile signal no matter what 

obstacle they were negotiating. Soldiers also commented that it became more difficult to 

interpret tactile signals when the signal strength weakened because of low battery power. 
20 

Suggestions for improvement included reducing the size of the battery, placing the unit in the 

cargo pocket, and decreasing battery consumption. See appendix C for detailed questionnaire 

results. 

4. Conclusions 

The tactile signal patterns were found to be intuitive and easy for the Soldiers to understand. 

Very little training time (less than 10 minutes) was required for Soldiers to become accurate in 

interpreting the four tactile signals used during the experiment. Results demonstrated that 

Soldiers performing IMT were able to receive, interpret, and accurately respond to the tactile 

commands faster than when the information was passed by a leader in the front of a wedge 

formation or by a leader in the back of a wedge formation using conventional hand and arm 

signals. Soldiers also commented they were better able to focus more attention on negotiating 

obstacles and on local area SA when they were receiving tactile signals than when maintaining 

visual contact with their leaders in order to receive standard hand and arm signals. 

The use of a tactile communication system can improve infantry team performance beyond that 

documented in this experiment. During this experiment, leaders in the front and rear of the 

Soldiers were not obscured by terrain, vegetation, or light level. In other words, the conditions 

of this experiment were optimal for the Soldiers’ abilities to see the conventional hand and arm 

signals. During combat situations, larger dispersions and obscurants could greatly inhibit 

reception of visual hand and arm signals. Visual barriers in an urban combat situation could 

impair hand and arm signaling. Also, hand and arm signals are traditionally passed along 

throughout the squad so that the time when the first squad member receives the signal could be 

much quicker than the time when the signal is passed to and received by the last squad member. 

A tactile communication system would allow simultaneous reception of signals by all squad 

members. For example, a “halt” signal sent by visual signals could result in a wave effect so that 

the last squad member to receive the signal could still be moving long past the time when the 

squad needed to stop. A “halt” signal sent by a tactile system could be received by all squad 

members in less than 2 seconds. A further benefit provided by a tactile system is the increased 

local SA experienced by the squad because the tactile system would free their eyes from having 

to watch for visual signals. A third benefit of adding a tactile system is the fact that Soldiers 

would have two means of receiving communication because the visual hand and arm signals 

would still be available for use. 

Suggestions for improvement of the tactile system include reduction of battery consumption and 

reduction of battery and receiver unit sizes. 
21 

5. Recommendations 

This experiment demonstrated that the addition of a tactile communication system creates the 

potential for increasing dismounted Soldier performance. Additional work should be accomplished to expand the lexicon of tactile language. A study should be conducted to document the 

upper boundary on the number of tactile commands that can easily be interpreted and understood 

by Soldiers operating in tactical environments such as military operations in urban terrain and 

wooded terrain. Work should be performed to evaluate the potential of incorporating the PDA 

transmitter function into PDAs or other computer systems already being planned for the 

dismounted Soldier. Evaluation of the potential for using a power source that is already planned 

for the dismounted Soldier should be performed. Finally, development of a means to send the 

tactile signals that do not require the removal of the Soldier’s hands from his weapon should be 

initiated. 
22 

6. References 

Elliott, L. R.; Redden, E.; Krausman, A.; Carstens, C.; Pettitt, R. Multi-modal displays to 

support Army infantry decision making and performance. In Proceedings of the 7th 

International Naturalistic Decision Making Conference, Amsterdam: The Netherlands, 

2005. 

Gilliland, K.; Schlegel, R. E. Tactile stimulation of the human head for information display. 

Human Factors 1994, 36, 700-717. 

Glumm, M.; Kehring, K.; White, T. Effects of Tactile, Visual, and Auditory Cues about Threat 

Location on Target Acquisition and Attention to Visual and Auditory Communications; ARL 

Technical report in process; U.S. Army Research Laboratory: Aberdeen Proving Ground, 

MD. 

Headquarters, Department of the Army. Military Occupational Classification and Structure; 

Pamphlet 611-21; Washington, DC, 31 March 1999. 

Jones, L. A.; Nakamura, M. Haptic displays: the tactile vest. In Proceedings of the 

Collaborative Technology Alliances Conference, 2003. 

Krausman, A.; Elliott, L. R.; Redden, E.; Petrov, P. Effects of Visual, Auditory, and Tactile 

Cues on Army Platoon Leader C3 Decision Making. Paper presented at the 10th 

International Command and Control Research and Technology Symposium, McLean, VA, 

2005. 

Mitchell, D. K.; Samms, C.; Glumm, M.; Krausman, A.; Brelsford, M.; Garrett, L. Improved 

performance research integration tool (IMPRINT) model analyses in support of the 

situational understanding as an enabler for unit of action maneuver team soldiers science 

and technology objective (STO) in support of future combat systems (FCS); ARL-TR-3405; 

U.S. Army Research Laboratory: Aberdeen Proving Ground, MD, 2004. 

Sklar, A. E.; Sarter, N. B. Good vibrations: Tactile feedback in support of attention allocation 

and human-automation coordination in event-driven domains. Human Factors 1999, 41, 

543-552. 

van Erp, J. B. Presenting directions with a vibro-tactile torso display. Ergonomics 2005, 48 (3), 

302-313. 

Wickens, C. D. Processing resources and attention; In D.L. Damos (Ed.), Multiple Task 

Performance, (pp. 3-34): Washington, DC: Taylor & Francis, 1991. 
23 

Appendix A. UCF Contractor’s Report (with minimal correction) 

Deliverable: CONTRACTOR REPORT (DRAFT) 

To: Dr. Elizabeth S. Redden, Chief, USAIC-HRED, Field Element, Army Research 

Laboratory, Ft. Benning, GA 

From: Dr. Richard Gilson (PI), LTC James Merlo, and Shawn Stafford 

University of Central Florida 

Service: Contractor support for ARL evaluation experiment 

Subject: Evaluation of Soldier tactile and arm and hand signals on an obstacle course 

Date: February 25, 2006 

The University of Central Florida (UCF) developed and produced a state-of-the-art tactile 

prototype display for Soldiers with signals presented around the torso in the abdomen area. The 

development and laboratory research for this design included a review of past literature and basic 

experiments conducted at the University of Central Florida to determine the preferred placement, 

frequency, duration, sequencing, etc. for intuitive tactile messages. To date only limited field 

research has been conducted using (sic) the prototype display units. Accordingly, UCF provided 

equipment and support to the Army Research Laboratory located at Fort Benning, Georgia, to 

conduct an assessment of these prototypes conveying standard Army hand signals to Soldiers via 

touch while engaged in an obstacle course. For operational validation, the Soldiers wore full 

field gear, including elbow and knee pads, over tactical vests and carried simulated M4 rifles. 

The following report is a brief synopsis of support activities and observations by University of 

Central Florida researchers. The results of the empirical data collection and a full report of the 

findings are being prepared by the Human Research and Engineering Directorate (HRED) of the 

U.S. Army Research Laboratory (ARL) at Fort Benning, GA, under the direction of Dr. Beth 

Redden. 

Equipment

Each tactile display assembly included eight custom-built electro-mechanical vibrotactile 

devices, hereafter known as “tactors” (see figure A-1). These eight tactors and their associated 

wiring were securely fitted into an elastic belt worn snugly around the torso (above the navel but 

below the sternum). This arrangement created a ring of equidistant stimulation loci with the first 

one centered just above the navel. A photograph of an exemplar tactor is shown in figure A-1. 

The center piston, visible with a midpoint screw, moves within larger fixed housing. 
24 

Figure A-1. Photograph of a single tactor, model C2, 

manufactured by Engineering Acoustics, 

Inc. These tactors are essentially acoustic 

transducers that transmit 200-300 Hz 

sinusoidal vibrations onto the skin. The 

mass of each tacton is 17 grams. 

The tactor controller box (TCB), designed by Engineering Acoustics, Incorporated, is powered by 

a 9.6-volt rechargeable battery (or six AA replaceable batteries). The TCB fires sequences of 

tactors in pre-coded patterns [specified by UCF] and actuates the individual tactors according to 

predetermined stimulus parameters [specified by UCF]. The sequences used for the ARL experiment were programmed and stored in the hardened TCB. The TCB wiring connects to the tactor 

belt through a cable (see figure A-2). The Soldiers wore the entire TCB and its battery pack in 

their right cargo pocket of either their BDUs or ECUs; participants wore both types. The 

sequences were activated remotely by means of a wireless Bluetooth personal data assistant 

(PDA). The software used to send signals to the TCB was designed by RIMLine llc in conjunction with and under the direction of University of Central Florida researchers. Photographs of 

the actual equipment are shown in figure A-2. 

 

Figure A-2. Three tactile displays belt assemblies are shown above along with their tactor controller boxes 

(TCBs). Each box includes a wireless Bluetooth receiver and the controlling circuitry. The 

picture on the right is the advanced robotics controller (lightweight) PDA that remotely sends 

the selected signal to the TCB to trigger the tactile message. 
25 

Tactile Signals

The four hand signals chosen for the experiment were “Attention,” “Halt,” “Rally,” and “Move 

Out”. The tactile representations of these signals were designed in a collaborative effort of 

scientists at the University of Central Florida and a consultant group of subject matter experts 

(SMEs) consisting of former U.S. Soldiers (1 Navy Seal, 1 Marine Force Recon, 1 Army Ranger, 

and 1 Army Special Forces Soldier). These sequences were then slightly modified in laboratory 

testing at the University of Central Florida and developed for this field test. 

A brief description of the signals follows: 

• Attention – sequenced side-to-side activation of front tactors, creating a “wave-like” 

motion 

• Halt – four tactors simultaneously actuated 

• Move Out –sequenced back-to-front activation of tactors, creating movement around each 

side of the body to converge in the front 

• Rally –sequenced activation of all tactors, creating a circular motion around the body 

The signals were separated individually from their originally intended operational sequences to 

test their individual reliability independently. Note the use of sequenced signals initially came 

from feedback from our SME team who suggested that an attention signal generally should be 

used to alert a Soldier of an incoming command, such as move-out or rally. However, the goal 

of this field test was to test each signal independently of the other signals, so no preparatory 

signal was used. 

Prior studies suggested that these field tests should work well. Physiological data collected in a 

laboratory at West Point showed that Cadets, even while under 80% max (sic) heart rate (induced 

by subjects running on a treadmill), were easily able to detect these signals. The purpose of this 

experiment was to determine whether Soldiers can both detect and understand these signals while 

completing a physically and attention demanding obstacle course, all within a more applied 

setting. 

Tactile Training

The following experimental protocol was designed exclusively by personnel from HRED of 

ARL. Each Soldier was given 7 to 10 minutes of familiarization with the tactile system before 

completing the obstacle course. Familiarization for every Soldier consisted of approximately 17 

repetitions of the four tactile signals: three repetitions without equipment, 4 times with 

equipment, and 2 times each in the kneeling, prone, combat roll, walk, and run positions/actions. 

Just before the Soldier started the obstacle course, a researcher presented and reviewed each 

tactile signal again to make sure the Soldier understood the signals. 
26 

Obstacle Course Testing

Each of 30 male Soldiers went through an IMT-Like obstacle course four times for a total of 120 

trials. The first trial was for training only, and the next three included data collection. During 

each trial, the Soldier moved out “on patrol” while spaced between two NCOs2, one of whom 

was approximately 10 paces in front (simulating a team leader) and the other was about 10 paces 

behind (simulating a squad leader). The Soldier’s mission was to negotiate each obstacle, while 

looking for hand signals from the front NCO, the rear NCO, or from the tactor belt with its 

wireless signals sent by a researcher. Nine signals (3 per condition, front, rear, or tactor) were 

given at different predetermined locations, and changed (sic) for each trial. At the same time, the 

Soldier was to maintain his scan and to call out if he spotted one of three shoulder badges/tabs 

that were placed on the ground [Airborne, Ranger, Special Forces]. Typically, a Soldier was 

able to spot one of the three badges during the seven minutes on average it took to complete the 

entire obstacle course. The main dependent variable was the time from the initiation of each 

signal to the time the Soldier called out that signal [accuracy was also recorded]. 

Informal Observations of the Tactile Signals

The UCF research team observed what appeared to be an intuitive grasp of the tactile signals by 

all the Soldiers, typically evidenced by rapid mastering of tactile commands after only three to 

four presentations during the training. Soldier response times for tactile signals during testing 

appeared quite consistent and somewhat faster than visual signals from the front and clearly 

superior to those presented visually from the rear position. It also appeared that during training 

as well as during the obstacle course trial itself that Soldier accuracy in identifying tactile 

commands was exceptional, despite the short period for training. Interestingly, these Soldiers 

who were taught arm and hand signals in basic training and again in AIT3

, made a number of 

errors on the arm and hand signals. This usually occurred while they were looking from the 

prone position or while engaged in a physical act. Comparatively, the newly learned tactile 

signals appeared unaffected by body orientation or ongoing physical movement. 

Observations of the Hardware

The prototype systems proved durable enough to allow 30 Soldiers to complete 120 trials 

through the 400-yard course with challenging obstacles. Notably, these same prototypes endured 

UCF, West Point, and the Naval Post graduate school testing and demonstrations in the prior 

6 months to this evaluation, including laboratory experiments, treadmill studies involving 

physiological stress, and numerous presentations while on travel. 

 2

non-commissioned officers 

3advanced individual training
27 

NCO feedback

The NCOs provided valuable feedback. In particular, they suggested that often-occurring 

“breaks in contact” should be far less likely with tactile communication. “Breaks in contact” 

take place in movement formations when Soldiers fail to receive or pass on visual arm and hand 

signals within a formation. NCOs also stated that night conditions and/or thick vegetation 

increase the response times for visual signals and that time delays in visually acquiring even an 

obvious hand signal can balloon by 4 times in a four-Soldier team as the signal is relayed across 

the team. In contrast, a demonstration of tactile signals with a four-Soldier fire team showed 

simultaneous receipt by each team member for the tested commands [i.e., “Move Out” and 

“Halt”]. 

Soldier Feedback

• Tactile arm and hand signals were easy to discriminate and identify quickly, without 

accuracy issues 

• Tactile system was comfortable to wear 

• System did not interfere with normal operations during IMT or on the obstacle course 

• Soldiers throughout the trials continued to offer possible applications for the tactile display 

and ideas for a tactile language 

• Soldiers wanted more tactile-coded arm and hand signals for expanded capability. 

• Soldiers expressed less difficulty with the normally divided tasks of looking around for 

obstacles (such as landmines) or looking in the distance for enemy activity, if hand signals 

were presented by touch rather than as another competing visual task. 

UCF-Considered Refinements

• Different connections between the tactor controller box and tactile belt to increase overall 

field worthiness, perhaps wireless. 

• Timing modifications for tactile patterns to facilitate absolute identification within 

sequences of messages, e.g., “Halt-Move Out/Direction-Rally” to help ensure error-free 

identification. 

• Comparing the need for preparatory commands in the field, when surrounded by 

contextually rich environments, versus in the laboratory where preparatory commands may 

not be as essential. 

• Detailed assessment of theoretical reductions in cognitive requirements and workload using 

touch as a parallel channel for information. 
28 

On behalf of the UCF research team, we would like to express our sincere gratitude to the U.S. 

Army Research Lab at Fort Benning, GA, for allowing us to support and observe this experiment. A special thanks goes (sic) to those Soldiers who performed as participants, many of 

whom are preparing to enter the operational Army to defend our nation. A blessing to them and 

to their families for all that they do. 
29 

Appendix B. IMT Course Layout 

Start 

Point

(A) 

Pipe 

Crawl

(B) 

Zig

Zag

(C) 2 Ft Jump

(E) Fox Hole (D) Hill

(F) Low Crawl

(G) Combat Roll (H) High Crawl (I) 

Kneeling 

Position

(J) 

Wall (K) 

Prone 

Position

(L) Urban Window 

and Stairs

(M) Stairs Finish Point

Start 

Point

(A) 

Pipe 

Crawl

(B) 

Zig

Zag

(C) 2 Ft Jump

(E) Fox Hole (D) Hill

(F) Low Crawl

(G) Combat Roll (H) High Crawl (I) 

Kneeling 

Position

(J) 

Wall (K) 

Prone 

Position

(L) Urban Window 

and Stairs

(M) Stairs Finish Point
30 

INTENTIONALLY LEFT BLANK
31 

Appendix C. Soldier Questionnaire Results 

DEMOGRAPHICS 

SAMPLE SIZE = 29 

SEX MOS RANK

 

Male – 29; Female - 0 11B – 28; 11C - 1 E-1 – 8 E-3 – 10 

 E-2 – 7 E-4 - 4 

 

AGE TIME IN CURRENT DUTY POSITION

 

21 (mean) 10 months (mean) 

 

1. What is your height? 70 inches (range is 65-74) 

2. What is your weight? 176 pounds (range is 120-242) 

3. Do you smoke? 6 Yes 23 No 

4. Are you color blind? 0 Yes 29 No 

5. Which is your dominant eye? 5 Left 24 Right 

6. Do you wear prescription lenses? 12 Yes 19 No 

7. If yes, which do you most often wear? 6 Glasses 6 Contacts 

8. Are you left-handed, right-handed, or ambidextrous? 

 2 Left-handed 26 Right-handed 1 Ambidextrous 

9. Have you ever served in combat or in a hostile fire zone? 

 0 Yes 29 No 
32 

TRAINING 

SAMPLE SIZE = 29* 

1. Using the scale below, please answer the following questions which are based on your training 

for the Tactile system. 

1 2 3 4 5 6 7 

Extremely bad Very bad Bad Neutral Good Very good Extremely good 

MEAN RESPONSE 

Length of training 5.79 

Level of detail 6.29 

Mix of lecture to hands-on exercise 6.31 

Overall quality of training 6.34 

2. Using the scale below, evaluate your ability to detect and understand each of the tactile signals 

based on your training today. 

1 2 3 4 5 6 7 

Extremely bad Very bad Bad Neutral Good Very good Extremely good 

TACTILE SIGNAL MEAN RESPONSE 

Halt 6.44 

Move out 5.96 

Rally 6.22 

Attention 6.22 

3. Using the scale below, evaluate your ability to detect and understand each of the Hand and 

Arm signals. 

1 2 3 4 5 6 7 

Extremely bad Very bad Bad Neutral Good Very good Extremely good 

HAND AND ARM SIGNALS MEAN RESPONSE 

Halt 6.64 

Move out 6.61 

Rally 6.43 

Attention 6.18 

* All 30 Soldiers completed training, but one Soldier failed to complete the training survey. 
33 

WOODLAND IMT 

SAMPLE SIZE = 30 

1. Using the scale below, please rate how easy or hard it was to see (or feel) each of the 8 signals 

you received during this trial. Each signal is identified by the location on the obstacle course and 

by the type of signal given. 

1 2 3 4 5 6 7 

Extremely hard Very hard Hard Neutral Easy Very easy Extremely easy 

Iteration 1 

Signal No. Location: Command Mean 

1 Pipe crawl: Tactile 5.17 

2 First bend: Rear 5.47 

3 Prone firing position: Front 5.70 

4 Second bend: Tactile 5.73 

5 High crawl: Rear 4.43 

6 High wall: Tactile 4.97 

7 Urban wall window: Rear 4.77 

8 Stairs: Front 5.70 

Iteration 2 

Signal No. 

1 Zigzag: Front 5.76 

2 Kneeling firing position: Rear 5.14 

3 Low crawl: Front 4.90 

4 Combat roll: Tactile 5.17 

5 High crawl: Rear 4.24 

6 High wall: Rear 4.50 

7 Urban wall: Front 5.21 

8 End point: Tactile 6.00 

Iteration 3 

Signal No. Location: Command Mean 

1 Start point run: Front 6.31 

2 Pipe crawl: Front 5.83 

3 Hill: Rear 5.21 

4 Low crawl: Tactile 5.86 

5 Kneeling firing position: Front 6.24 

6 Prone firing position: Tactile 6.24 

7 Urban wall: Tactile 6.10 

8 Stairs: Rear 5.24 
34 

2. Using the scale below, how easy or hard was it to do the following? 

 a. See (or feel) the signal: 

 Mean 

From the Front 6.14 

From the Rear 4.63 

With Tactile belt 6.19 

 b. To interpret the signal: 

 Mean 

From the Front 6.02 

From the Rear 4.97 

With Tactile belt 6.03 

 c. To learn the signals: 

 Mean 

Army Hand & Arm signals 6.13 

Tactile signals 6.43 

Comments No. of Responses

This system is great! 3 

I think that this system is a good idea and worth the investment. 2 

I liked them. Easy to use and not always having to look around. You can focus on 

your mission. 

1 

The system seemed to become progressively more and more communicable as the 

iterations progressed up to the third iteration. By the third iteration, the tactile belt was 

easier and quicker to understand than clearly visible hand and arm signals. 

1 

Adaptation to the tactile system is fairly quick. Tactile system 

 response time to signals is faster than hand signals alone. 

1 

The reaction time with the communication systems were generally consistent as 

opposed to the hand signals. This can definitely help out with moving large amounts 

of people and coordinating movements. 

2 

Found it very easy to know what signal or action I needed to perform with the belt. As 

to where, I found my self guessing on some of the rear hand signals. 

1 

Overall, the tactile belt had major advantages over conventional hand signals. The 

only major concerns with the use of the tactile belt would be when interacting with 

equipment that produces loud noises or a lot of vibrations.

1 

Still like the belt. I think as long as you are trained on the system it will work well. 1 

Signal strength was extremely low resulting in missed and confused interpretations. 1 

The batteries on the belt were not as strong, so it was hard to distinguish while 

crawling. 

1 

It was a bit difficult to distinguish the tactics signals due to a low battery. 
35 

Still had some trouble making out the signals; I had to second guess myself once in a 

while. 

2 

Battery system bulky. Unreliable with current power source. 1 

Needs a better power source; other than that, no problems. 1 

Battery strength was lower leading to less vibration felt from the belt. 1 

The box in my cargo pocket caused some discomfort during the crawling portion. 1 

The belt was better with the batteries at full charge. The vibration was stronger with 

the batteries at full charge. 

1 

Potential sound from the sensors vibrating against bone or solid structures. 1 

Use more iterations with the tactile belt. 1 

It is hard to make out the belt signals when you are doing a combat role, or are in the 

prone position. I think the pulses need to be stronger, but not to extreme, when my 

heart rate was up it made it harder 

1 

I think the vibration in the belt should be intensified a little bit. 3 

Clashed with body location and current gear. 1 

Additional training and time is needed with the belt to allow it to become almost 

second nature for reacting to vs thinking of the belt directly. 

1 

The different signals on the tactile belt were very easy to distinguish from each other 

regardless of position or activity. I had more of a delayed reaction with the hand 

signals. 

1 

Battery/computer are slightly bulky in the cargo pocket. 1 

I’m not so sure how it will work under combat conditions. I have never been in 

combat but I do know that when your adrenalin is rushing your senses are impaired. 

The belt requires your senses (sense of touch). 

1 

During a combat role some motions of the tactile belt become hard to distinguish due 

to where the gear hits the body. 

1 

Signals are difficult to see and/or interpret in general, especially with the helmet and 

gear on. Whereas the tactile system allows you to dedicate more effort to 

maintaining security and staying in view of your change of command. 

1 

I believe that the tactics signal for move out should be on one side of the waist as 

opposed to both sides of the waist to make it easier to distinguish. 

1 

It is much easier to know there is a communication being sent with the tactile signals. 

I believe interpretation is simply a matter of using the system more. 

1 

In this iteration, I noticed that the tactile belt helped with communicating through 

obstacles. When climbing over the urban wall, I was not able to see the hand signal 

being given until I cleared the wall. With the belt I would be able to receive the 

comm.. 

1 

After familiarization with the tactile belt, I found myself waiting for a signal from the 

belt and focusing visual perception on locating the objectives. Still the signal needs 

to be stronger and more distinguishable. 

1 
36 

3. Were there any safety issues or problems with the tactile belt system you used during this 

trial? 

 0 Yes 

 30 No 

Comments No. of Responses

Well organized course. 2 

Reaction time was slowed down due to frequent adjusting of loose kneepads and 

Kevlar4. 

1 

When walking “move out” can feel a lot like “attention.” 1 

How well will the device hold up in rough terrain? 1 

The use of the tactile belt can actually be safer when negotiating obstacles since the 

user doesn’t have to look for a hand signal and concentrate on the obstacle. 

1 

Only one thing, just a smaller battery. 1 

 4Kevlar is a registered trademark of E.I. DuPont de Nemours & Co., Inc. 
37 

NO. OF 

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 1 DEFENSE TECHNICAL 

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38 

NO. OF 

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