NISTIR 7484 

February 2008 

NISTIR 7484 02/28/2008 

A Study of Users with Visual 

Disabilities and a Fingerprint 

Process

Brian Stanton

Mary Theofanos

Charles Sheppard
NISTIR 7484 02/28/2008 

Table of Contents

1 EXECUTIVE SUMMARY ................................................................................................................................ 4

2 INTRODUCTION .............................................................................................................................................. 6

3 METHODOLOGY ............................................................................................................................................. 6

4 PARTICIPANTS ................................................................................................................................................ 7

5 STUDY ................................................................................................................................................................ 8

5.1 PARTICIPANTS .................................................................................................................................................. 8

5.2 EQUIPMENT ...................................................................................................................................................... 8

5.2.1 Fingerprint Scan Process Indicators ..................................................................................................... 10

5.2.2 Tones ................................................................................................................................................... 10

5.2.3 Vibration .............................................................................................................................................. 10

5.3 PROCEDURE ................................................................................................................................................... 10

6 RESULTS ......................................................................................................................................................... 13

7 DISCUSSION ................................................................................................................................................... 15

7.1 LOCATING ...................................................................................................................................................... 15

7.2 HAND PLACEMENT ......................................................................................................................................... 16

7.3 SCAN DURATION ............................................................................................................................................ 16

8 SUMMARY ...................................................................................................................................................... 17

9 REFERENCES ................................................................................................................................................. 19

APPENDIX A ............................................................................................................................................................. 20

APPENDIX B ............................................................................................................................................................. 21

APPENDIX C ............................................................................................................................................................. 22

APPENDIX D ............................................................................................................................................................. 25
NISTIR 7484 02/28/2008 

List of Figures

FIGURE 1 FINGERPRINT SCANNER MOCKUP ................................................................................................................... 9

FIGURE 2 FINGERPRINT SCANNER TEXTURE PLACEMENT .............................................................................................. 9

FIGURE 3 FINGERPRINT SCANNING PROCESS ................................................................................................................ 12
NISTIR 7484 02/28/2008 

1 Executive Summary 

The Department of Homeland Security’s (DHS) United States Visitor and Immigrant Status 

Indicator Technology (US-VISIT) program is a biometrically-enhanced identification system 

primarily situated at border points of entry such as airports and seaports. Section 508 applies to 

accessibility of US-VISIT when it procures, develops, maintains, or uses Electronic and 

Information Technology (EIT) products. The NIST Biometrics Usability group performed a 

usability test to study the interaction of people with disabilities with fingerprint devices. 

This report presents the results of a usability study that examined how persons with visual 

impairments interact with a fingerprint scanner. The study was designed to investigate how 

those with a visual impairment: 

1. locate the scanning device 

2. properly place their hand on the device 

3. determine the duration of a fingerprint scan. 

This study was executed as follows: first, we interviewed ten federal employees from a pool of 

17 candidates about their experiences with fingerprinting in order to understand the user 

population and their needs. Based on this feedback, ten participants participated in the study. 

Each participant performed three different trials. For each trial, the participant located the 

scanner by a tone. They used a textured surface to identify the proper hand position. Tones and 

haptic feedback were employed to demarcate the scanning process. Finally, they listened to six 

tones that are commonly used by the visually impaired community as indicators to identify the 

most appropriate or pleasing tones. 

This report describes four main results. 

1. Audio tones are effective for locating the device. The visually impaired participants had 

little or no difficulty locating the fingerprint scanner mockup using tones. 

2. Textured surfaces can be used for determining proper hand placement. All but one 

participant were able to position their hand appropriately. 

3. Audio tones and haptic input are effective in providing an indication of duration. 

4. In order for the duration indicator to be effective the indicator must be associated with a 

process. 

The finding that the duration of the scan must be associated with a process has broad 

implications for fingerprint devices. In previous usability tests we observed users struggling to 

determine when to place and remove their hands from the device. The results of this study 

suggest that the indicators used were not perceived as indicative of the capture process. Further 
NISTIR 7484 02/28/2008 

testing is required to determine how best to represent the process and the duration of the scan to 

the larger population of fingerprint users. 

Finally, this study was specifically designed to study interaction with fingerprint devices for 

those with visual impairments. But how will people with differing abilities use fingerprint 

devices? Users may be too diverse for a biometric device to provide enough information to all 

users. Instead of the users adapting to the device, the device could adapt to the user. Additional 

research is required to explore the usefulness of adaptive technologies for biometric applications. 
NISTIR 7484 02/28/2008 

 

2 Introduction 

The Department of Homeland Security’s (DHS) United States Visitor and Immigrant Status 

Indicator Technology (US-VISIT) is a biometrically-enhanced identification system primarily 

situated at border points of entry such as airports and seaports. US-VISIT processing currently 

applies to most non-citizens entering the United States, regardless of country of origin and mode 

of transportation. The US-VISIT program has a number of committees and programs that are 

developing processes to meet the functional performance criteria and technical standards of 

Section 508 of the Rehabilitation Act (United States Code Title 29 Section 794d), as amended in 

the Workforce Reinvestment Act of 1998. Section 508 applies to US-VISIT when it procures, 

develops, maintains, or uses Electronic and Information Technology (EIT) products. Under 

Section 508, Federal agencies must give employees with disabilities and members of the public 

“access to and use of information and data that is comparable to the access to and use of” 

information and data available to Federal employees without disabilities [1]. 

Research is required to understand how people with disabilities interact with biometrics devices 

in order to support US-VISIT’s efforts to specify requirements and processes for complying with 

Section 508. Studying the interaction of people with disabilities and biometric devices will help 

identify new and improved requirements for biometric device developers and will improve the 

implementation and processes for US-VISIT programs for people with disabilities. 

Previous usability studies performed by the NIST Biometrics Usability team examined how to 

present instructional information to users [2]. Users accustomed with leaving two index 

fingerprints at US-VISIT may not be familiar with the ten slap fingerprint capture process. The 

study compared three methods of presenting instructions to users. Observing 300 users 

interacting with a fingerprint scanner, iris, and face cameras identified significant shortcomings 

that could be magnified for users with disabilities. These findings became the basis of this 

follow-up study1 that examines how users with visual impairments interact with fingerprint 

scanners. 

3 Methodology 

Although the Biometrics Usability team has performed extensive research on Section 508 and 

Web applications with persons with visual disabilities [3,4], we had no experience or personal 

1 These tests were performed for the Department of Homeland Security in accordance with section 303 of the 

Border Security Act, codified as 8 U.S.C. 1732. Specific hardware and software products identified in this 

report were used in order to perform the evaluations described in this document. In no case does such 

identification imply recommendation or endorsement by the National Institute of Standards and Technology, 

nor does it imply that the products and equipment identified are necessarily the best available for the purpose.
NISTIR 7484 02/28/2008 

understanding of what the visual disability issues would be when using an electronic 

fingerprinting device. We decided to first interview several people with visual disabilities to 

better understand the user population and their needs. 

Based on the feedback of the interviews an exploratory or formative study was conducted to 

investigate how users with visual disabilities locate a fingerprint device, position a hand on a 

fingerprinting device, and identify the start and the end of a fingerprint scan. 

4 Participants 

Ten volunteers out of a pool of 17 contacts who had participated in previous usabilityaccessibility research participated in the interviews and the follow-up study. All interviewees 

were federal government employees, with a visual impairment. Four of the participants self -

declared as having “low vision” and six self-declared as “blind”. Additional information about 

the participants is presented in Appendix C. 

Each participant was provided with the background for the study and asked the following 

questions: 

1. Have you ever been fingerprinted? What was that experience like? 

2. What cues would you recommend to help make the fingerprint process more independent 

or accessible? 

3. Have you had any experience with iris scanning? How would you recommend that iris 

scanning be addressed? 

4. Are there any other biometric processes that you have experienced? 

5. Would you like to participate in a usability study that will refine the design of digital 

fingerprint scanning in an effort to define requirements for making the process more 

accessible? 

Each of the ten participants had experience with paper and ink rolled prints. In order to collect 

these prints each was assisted by an administrator who had asked for a hand, explaining that they 

were putting a finger onto an ink pad and that they would then roll the finger on the paper. This 

process was repeated for each finger of each hand. Four participants had used a digital 

fingerprint scanner. Again, each was assisted by an administrator placing the appropriate fingers 

on the scanner. One participant recalled presenting each finger individually on a small scanning 

surface. 

All but one participant, who had some vision, had suggestions on how to improve the process for 

independence and accessibility. The suggestions fell into three categories. First, six participants 

suggested tactile cues such as contrasting surfaces or raised markings or notches for placing and 

positioning fingers. Three participants recommended audio cues such as beeps to indicate the end 

of the procedure. Verbal directions with manual guidance from the operator was suggested by 

three of the participants. The individual responses are presented in Appendix C. 
NISTIR 7484 02/28/2008 

None of the participants had any experience with iris scans but offered comments and 

recommendations on the process as enumerated in Appendix D. Although all of the participants 

were intrigued by the possibility of iris scans, most believed it would be impossible due to 

multiple factors such as opaque prosthetic shells, artificial eyes, and anaridia (absence of the 

iris). 

None of the participants had any other experiences with biometric devices. All were excited 

about the opportunity to participate in usability testing of biometric devices and volunteered for 

the second phase of the study. 

5 Study 

Based on our interviews, we chose to investigate three factors of the interaction between 

“livescan” (i.e., fully electronic capture) fingerprint sensors and the visually impaired: 

1. locating the scanning device, 

2. properly placing a hand on the scanner, 

3. determining the duration of a fingerprint scan.. 

We were also interested in the participants' opinions on the usefulness of different tones in a 

biometric context. 

5.1 Participants 

This study included 12 participants—the ten from the telephone interviews and two colleagues of 

the interviewees. All were federal government employees with some level of visual impairment 

as described above. All indicated that they had no hearing impairment. 

5.2 Equipment 

Since there was no available commercial fingerprint scanner where we could control all of the 

necessary parameters for this study, the equipment consisted of a mockup of a fingerprint 

scanner. The scanner mockup was 8.5 mm x 9 mm x 30 mm (see Figure 1 Fingerprint Scanner 

Mockup). 

Inside the clear acrylic box, a speaker was mounted on the front and a vibration unit near the top. 

Overlaying the top surface was a sheet of Gila Decorative Window Film (crackled glass) to 

provide a textured surface. The window film was cut to the size of the top surface with a section 

cutout toward the front of the box (see Figure 2 Fingerprint Scanner Texture Placement). This 

cutout allowed the smooth surface of the box to be exposed. 
NISTIR 7484 02/28/2008 

Figure 1 Fingerprint Scanner Mockup 

Figure 2 Fingerprint Scanner Texture Placement 
5.2.1 Fingerprint Scan Process Indicators 

We investigated two different methods to indicate the fingerprint scanning process, tones and 

vibration. 

5.2.2 Tones 

First, a tone was selected as a location indicator. This tone had a duration of 0.15 seconds or 

less, and repeated at one-second intervals in accordance with the Manual on Uniform Traffic 

Control Devices [5]. 

Three different tones were developed for indicating the scanning process. 

Indicator Tone 1: A one second tone at 1000 Hz 

Indicator Tone 2: A three second tone at 1000 Hz 

Indicator Tone 3: There were two “variations on a theme” for Tone 3 

Tone 3a: An eight second series of tones separated by one second to one half seconds in 

decreasing intervals, a short pause, then two quick beeps 

Tone 3b: An eight second series of tones separated by one second to one half seconds in 

decreasing intervals

In conjunction with the tones developed for the scanning process, we selected six tones that are 

commonly used by the visually impaired community as indicators. These were: 

• A crosswalk button locator tone used in Prisma Teknik’s Accessible Pedestrian Symbols 

(APS)[6] 

• A crosswalk crossing set of rapid beeps used in Prisma Teknik’s APS 

• A crosswalk crossing “cuckoo” sound used in Mallory Sonalert APS 

• A crosswalk crossing “chirp” sound used in Mallory Sonalert APS 

• Another type of crosswalk crossing “chirping” used by Novax Industries APS 

The locator sound from the above study. 

5.2.3 Vibration 

A device was placed within the scanner mockup that was turned off and on remotely and created 

a vibration that could be felt when a hand was placed on the top of the mockup. 

5.3 Procedure 

NISTIR 7484 02/28/2008 

The participant was welcomed into the room where the study was to be conducted. The consent 

form was reviewed and signed. Next, the participant was informed that the purpose of the study 

was to investigate the use of electronic fingerprint scanning with people with differing levels of 

visual acuity. He or she was told that there was a mockup of a scanner, “a little bigger than a 

shoebox” on a table in front of him/her. This mockup was going to emit a sound and that the 

participant should locate the scanner using this sound and place one hand on top of the mockup 

where he/she thought the hand should be placed. The participant was also told that once he/she 
NISTIR 7484 02/28/2008 

placed his/her hand on the scanner he/she should press down on the scanner and that the scanner 

would indicate, in some way, both that a scan had begun and that the scan had ended. The 

participant was asked to inform the study conductor when they thought the scan had begun and 

then lift his/her hand when the scan had ended. First, the participant was to locate the sensor 

mockup by a tone. Second, he/she was to use the textured surface to identify where he/she 

should place his/her hand for the scan. Finally, the participant was asked to inform the facilitator 

when the scan began and when it ended. The participant was also informed that there would be 

three trials of this procedure. This procedure is illustrated in Figure 3. The first four participants 

received the following indications: 

Group 1 (Start Tone & Stop Vibrate, Continuous Tone, Continuous Vibration): 

Trial one: Tone 1 indicated the start of the scan and a vibration indicated the end. 

Trial two: Continuous Tone 2 indicated the scanning duration. 

Trial three: An eight second continuous vibration indicated the scanning duration. 

Since we were following a formative testing procedure, the results (see Results) for the first 

group were analyzed and the indicators were changed for the next group of five participants: 

Group 2 (Start & Stop Tone, Continuous Vibration, Speedup Tone A): 

Trial one: Tone 1 indicated the start and the stop of the scan. 

Trial two: An eight second continuous vibration indicated the scanning duration. 

Trial three: Tone 3a indicated the scanning duration. 

The results for the second group were analyzed and the indicators were changed for the next 

group of three participants: 

Group 3 (Start & Stop Tone, Continuous Vibration, Speedup Tone B): 

Trial one: Tone 1 indicated the start and the stop of the scan. 

Trial two: An eight second continuous vibration indicated the scanning duration. 

Trial three: Tone 3b indicated the scanning duration. 

After the three trials, each group of participants listened to six tones and gave their opinions on 

how appropriate they thought the sound would be in a biometric application. 
NISTIR 7484 02/28/2008 

Figure 3 Fingerprint Scanning Process 
6 Results 

As presented in Table l, participants successfully located the scanner using the locator tone. 

Only one participant had any difficulty. In addition, all but one participant were able to correctly 

position their hand on the scanner using the textured surface. 

Table 1 Location and Hand Placement with Scanner 

Group Participant 

number Vision Located Placement 

1*

1 None OK OK 

NISTIR 7484 02/28/2008 

2 None Ok Ok 

3 None Ok Ok 

4 None Ok Ok 

2† 

5 Low Ok Ok 

6 None Ok Ok 

7 None Ok Ok 

8 None Ok Ok 

9 None Ok Ok 

10 Low Ok Ok 

3‡ 11 Low With difficulty Ok 

12 None Ok No 

* Start Tone & Stop Vibrate, Continuous Tone, Continuous Vibration 

† Start & Stop Tone, Continuous Vibration, Speedup Tone A 

‡ Start & Stop Tone, Continuous Vibration, Speedup Tone B 

Table 2 Group One shows that for the first group in trial one only one out of the four participants 

understood that the vibration indicated the scan was over. Likewise, only one participant 

understood that the cessation of the beeping indicated that the scan had ended in trial two. 

However, in the third trial all but one participant understood that the stopping of the vibration 

indicated the end of the scan. 

Given the participant’s difficulty in understanding these cues we modified the test for the second 

group. Trial one was changed from a vibration indicating the end of the scan to a second beep. 

The constant beeping in trial two was replaced with Tone 3a as a new trial three (with group 

one’s trial three as the new trial two). 
NISTIR 7484 02/28/2008 

Table 2 Group One (Start Tone & Stop Vibrate, Continuous Tone, Continuous Vibration) 

Participant 

number Vision 

Trial One Trial Two Trial Three 

Start 

beep 

End 

vibrate 

Start beeping 

started 

End beeping 

ceased 

Start 

vibration 

started 

End 

vibration 

ceased 

1 None Ok Unclear Ok Ok Ok Ok 

2 None Ok No No No Ok No 

3 None Ok Ok Ok No Ok Ok 

4 None Ok Unclear Ok No Ok Ok 

Group two’s results( as shown in Table 3) show that the ending beep in trial one and the 

accelerating beeping in trial three were not very effective. Participants were apparently mislead 

by the gap before the final two beeps in tone 3a. Even participant 9, who correctly interpreted 

the tone, mentioned that it could be misleading. The constant vibration throughout the scan in 

trial two was correctly indentified (participant eight’s data was lost due to equipment 

malfunction). 

Table 3 Group Two (Start & Stop Tone, Continuous Vibration, Speedup Tone A) 

Participant number Vision 

Trial One Trial Two Trial Three 

Start 

beep End beep 

Start 

vibrate 

End 

vibrate ceased 

Start 

beep 

Accelerated 

beep ceased 

5 Low Ok Ok Ok Ok Ok no (gap) 

6 None Ok No Ok Ok Ok no (gap) 

8 None 

9 None Ok No Ok Ok Ok ok (gap) 

For the final group of three participants we removed the gap before the final two beeps for the 

accelerated beeping condition. All participants correctly identified the scan duration in the 

vibration and accelerating beeping condition. Two of the three participants could identify the 

scan duration when the scan began and ended with a single beep (see Table 4 Group Three). 

Table 4 Group Three (Start & Stop Tone, Continuous Vibration, Speedup Tone B) 

Participant 

number Vision 

Trial One Trial Two Trial Three 

Start 

beep 

End 

beep 

Start 

vibrate 

End vibrate 

ceased Start beeping 

Accelerated beep 

ceased 

10 Low Ok Ok Ok Ok Ok Ok (no gap) 

11 Low No No Ok Ok Ok Ok (no gap) 

12 None No Ok Ok Ok Ok Ok (no gap) 

As shown in Table 5, when presented with the six tones, all participants preferred Tone 6 ( the 

locator tone used in this study). 
NISTIR 7484 02/28/2008 

Table 5 Tone Preference 

Group Participant number Vision Tone 1 Tone 2 Tone 3 Tone 4 Tone 5 Tone 6 

1*

1 None Just OK No No No No OK (best) 

2 None OK No Just OK No Ok OK (best) 

3 None Ok Ok Ok (best) Ok Ok OK (best) 

4 None No No No No No Ok 

2†

5 Low No No Ok Ok Ok Good 

6 None No Ok Ok Ok Good Best 

8 

9 None No Ok No No Ok Ok 

3‡

10 Low Ok No Just ok No No Ok 

11 Low No Ok Ok Ok Ok Ok 

12 Ok No No No No Ok 

1. A crosswalk button locator tone used in Prisma Teknik’s Accessible Pedestrian Sysmbols (APS) 

2. A crosswalk crossing set of rapid beeps used in Prisma Teknik’s APS 

3. A crosswalk crossing “cuckoo” sound used in Mallory Sonalert APS 

4. A crosswalk crossing “chirp” sound used in Mallory Sonalert APS 

5. Another type of crosswalk crossing “chirping” used by Novax Industries APS 

6. The locator sound from the this study 

* Start Tone & Stop Vibrate, Continuous Tone, Continuous Vibration 

† Start & Stop Tone, Continuous Vibration, Speedup Tone A 

‡ Start & Stop Tone, Continuous Vibration, Speedup Tone B 

7 Discussion 

7.1 Locating 

The visually impaired participants in this study had little or no difficulty locating the fingerprint 

scanner mockup. This finding is encouraging as it implies that audio cues would be an effective 

method to indicate the location of a biometric device in an operational setting. 

The tone preference results (see Table 5) provide clues as to the characteristics of an appropriate 

locator tone. When looking at the participants’ comments on the tones, commonly desired 

attributes appear. Tone 6 (the tone used in this study) was universally liked. Participants 

commented that this tone sounded “more like an electronic device” and would be “more distinct 

from background sounds”. However, a few participants wanted the locator tone to be louder. 

Tones 3, 4, and 5 were all variations on a bird chirping. Participants were mixed in their 

opinions on these tones. These tones were rated as easily heard, but concerns were expressed 

about these tones being confused with real bird calls. However, participant 3, an expert on 

audible cues for the visually impaired, highly rated the bird call tones. She felt that the “falling 
NISTIR 7484 02/28/2008 

third” tonal drop would draw people’s attention and would be good if someone had hearing loss 

in one of the frequencies used. 

When asked, participants reported that they judged the tones on how easily the tone could be 

heard in a noisy ambient environment and how distinct it was from other noises. At the same 

time, participants wanted the tone not to be “annoying”, “distracting” or too loud. Another 

common finding was that participants wanted the locator tone to sound only until they learned 

where the scanner was located. Once the location was determined and remembered, they 

preferred that the locator tone not sound. There was an implication that the scanner should be 

able to determine who needed the locator tone. 

Given the complex requirements of what comprises a locator tone (how loud it should be, and 

how often it should sound) more detailed research could be performed in this area. 

7.2 Hand Placement 

Only one participant was unable to position a hand on the smooth area within the textured 

surface of the scanner mockup. This participant did have some vision and was able to see into 

the scanner (since it was made of clear acrylic) and see the speaker and vibration assembly. The 

participant reported that it appeared she would be reaching into the scanner and was therefore 

unwilling to place her hand on any operating equipment. All other participants reported that they 

had little or no difficulty determining where to place their hands and that the textured surface 

was easily differentiated. Interestingly, many participants expressed that even people with 

lessened tactile sensitivity (such as caused by diabetes) would still be able to distinguish between 

the textured and smooth surfaces. 

7.3 Scan Duration 

Three groups of participants experienced three different scan duration indicators. 

In the first group of participants (Start Tone & Stop Vibrate, Continuous Tone, Continuous 

Vibration), the majority did not recognize that the scan had ended when a vibration was felt. We 

had initially thought that a vibration would cause the participants to pull their hand away from 

the machine in surprise of the unexpected vibration. This did not turn out to be the case. 

Instead, participants were confused by the mismatch between the two different signaling modes 

(i.e., from audible to haptic). In the second trial of the first group, participants were uncertain 

what the cessation of the steady beeping meant. In their remarks some mentioned waiting for 

something to happen after the beeping stopped. Participants did not make a strong connection 

between the scanning process and the beeping. 

In the third trial of the first group, all but one of the participants correctly identified when the 

simulated scan was over. The vibration had a strong association with the process of scanning. 

One participant commented on how the vibration made him think of a machine-like process, like 

the vibration made from the scanning mechanism. Although most of the participants correctly 

indicated when the scan was complete, many said that they had “guessed” at the meaning of the 

vibration stopping. Nevertheless, this guesswork proved to be correct. 
NISTIR 7484 02/28/2008 

The second group of participants (Start & Stop Tone, Continuous Vibration, Speedup Tone A) 

again received three different indicators of the scanning process. Since the trial with the 

vibration indicating the end of the scan faired so poorly, it was replaced with a trial consisting of 

a starting beep and an ending beep. Although in group one the participants suggested that they 

might understand better if the starting and stopping indicators were of the same type (e.g., both 

beeps), this behavior was not observed with the second group. 

Trial two for the second group of participants consisted of the same vibratory indicator as in 

group one’s trial three. Again, the steady vibration during the simulated scan was understood 

well. 

The third trial for group two was a series of beeps during the simulated scanning process. As we 

listened to the previous two groups’ comments, we wanted an indicator sound that was more 

representative of a process. A house alarm arming system indicator was used as a model. The 

arming indicator was a series of beeps with progressively less time between beeps to indicate the 

approaching time of the alarm activation. As this accelerating beeping was deemed to be 

indicative of requiring an action on the part of the listener, we constructed a series of beeps based 

on the alarm system. At the end of the arming system indicator there was a pause followed by 

two beeps to indicate that the system was now armed. This gap proved to be very confusing to 

the participants. Most participants assumed the scan had ended before the two final beeps. 

Group three (Start & Stop Tone, Continuous Vibration, Speedup Tone B) had the same trials as 

group two but for the third trial the final two beeps were removed. When these beeps were 

removed, all participants correctly identified the end of the simulated scan. As with the results 

from group two, the steady vibration was better understood than the start and end beep trial. 

8 Summary 

In this study we examined the use of audio, haptic, and tactile input to assist users with visual 

disabilities interact with fingerprint devices. Specifically we focused on input for locating the 

scanning device, for properly placing a hand on the scanner, and for determining the duration of 

a fingerprint scan. We found that audio tones are effective for locating the device. Textured 

surfaces can be used for determining proper hand placement. Finally, audio tones and haptic 

input are effective in providing an indication of scan duration. However, we found that in order 

for the duration indicator to be effective the indicator must be indicative of a process. For 

example, consider the progress bar in many computer applications. Our finding that a single 

tone at the beginning and end was confusing to participants is consistent with this hypothesis. 

This finding has much broader implications for fingerprint devices. 

In previous usability tests [2], we have observed many users struggling to determine when to 

place and remove their hands from the fingerprint device. Users were not certain when the 

process started and ended based on the lights. Based on results from this accessibility testing, this 

is likely due to the fact that for the study participants these lights were not indicative of the 

process. Further testing is required to determine how best to represent the process and the 

duration of the scan to the larger population of fingerprint users. 
NISTIR 7484 02/28/2008 

We also noticed that many of the participants of this accessibility study were very concerned 

about other types of disabilities. Several participants commented that the audio tones would not 

be appropriate for users with hearing impairments. This test was specifically designed to study 

interaction with fingerprint devices for those with visual impairments. However, their concerns 

raise the bigger question of how will people with differing abilities use fingerprint devices? 

Users may be too diverse for a biometric device to provide the necessary information for all 

users. 

One size does not necessarily fit all. Instead of the users adapting to the device, the device could 

adapt to the user. A user should be able to take their personal profile to the system and the 

system should be able to use that profile to customize itself to meet the individual’s needs. 

Consider the following scenario: As a user approaches the biometric sensors, a signal is sent to 

the system that indicates a user’s desires or requirements. The system acts on the signal, enabling 

or disabling various features based on the user’s requirements. When the user is ready to present 

his/her biometrics, the system has been automatically configured in a personalized fashion. Thus 

for someone who has a visual impairment the system might use tones; for someone with a 

hearing impairment the system might use lights. 

Such adaptive technologies have potential beyond Section 508 accessibility requirements [7]. 

For example, consider an unattended physical access control point, such as a biometrically 

enabled door, and a user that has expressed a distrust (for example from some perceived safety 

concerns) for a particular biometric (e.g., a false belief that an iris camera may damage their 

eyes). If an access badge was outfitted with a signaling technology, then such a system could 

read a user’s preferences from a distance, and prepare a substitute modality, such as a fingerprint. 

Adaptive capabilities could also be extended beyond purely biometric needs -- consider an 

adaptive system at an unattended airport tarmac entry/exit point. A longer-range radio frequency 

identification (RFID) badge could broadcast that a particular category of transportation worker 

that moves heavy equipment needs to have the electronic door held open longer so they can enter 

and exit without fear of a door prematurely shutting [8]. 

Additional research is required to determine the usefulness of adaptive technologies for 

biometric applications. 
NISTIR 7484 02/28/2008 

9 References 

[1] Department of Homeland Security (2007, May 7). US-VISIT Section 508 Compliance 

Process Description. 

[2] Theofanos, M.F., Stanton, B., Orandi, S., Micheals, R.J., Zhang, N.F. (2007). Usability 

Testing of Ten-Print Fingerprint Capture. National Institute of Standards and Technology. NIST 

IR 7403 Retrieved December 4, 2007 from http://zing.ncsl.nist.gov/biousa/docs/NISTIR-7403-

Ten-Print-Study-03052007.pdf . 

[3] Theofanos, M. F. and Redish, J. C., (2003, November-December), Guidelines for accessible 

and usable websites: Observing users who work with screen readers, Interactions, X, 6, 38-51. 

(This article is also available on 

http://www.redish.net/content/papers/InteractionsPaperAuthorsVer.pdf 

http://www.redish.net/content/papers/interactions.html.) 

[4] Theofanos, M. F. and Redish, J. C., (2005, February), Helping low-vision and other users 

with web sites that meet their needs: Is one site for all feasible?, Technical 

Communication, 52, 1, 9 – 20. 

[5] U.S. Department of Transportation, Federal Highway Administration (2003). Manual on 

Uniform Traffic Control Devices for Streets and Highways. Washington, DC: U.S. Government 

Printing Office. 

[6] Prisma Teknik’s Accessible Pedestrian Symbols from www.walkingInfo.org/APS . 

[7]Stanton, B. (2007). Biometric Accessibility, A Study on Assistive Methods for the Visually 

Impaired. Presented at the Biometric Consortium Conference 2007, Baltimore, Maryland. 

[8] (Department of Homeland Security, 2007)] Micheals, R., Private Communication, November 

2007. 

Acknowledgements 

The authors would like to thank Kevin Mangold and Shahram Orandi for their assistance in the 

construction of the mock fingerprint sensor. 
NISTIR 7484 02/28/2008 

APPENDIX A 

Demographic Questionnaire 

 

3. Handedness 

 Right Handed 

 Left Handed

 Ambidextrous

4. Height 

Feet Inches

5. Country of Origin 6. Profession 
NISTIR 7484 02/28/2008 

APPENDIX B 

Instructions 

We’re studying the use of electronic fingerprint scanning of people with differing levels of 

visual acuity. We are going to go a different room. In this room there will be a table 

approximately (5’) in front of you. On this table there’s a mockup of a fingerprint scanner, a 

little bigger than a shoebox. 

After entering the room, the scanner will start to emit a tone. Using this tone, I would like 

you to locate the scanner. On top of the scanner, there is an area where the image of your 

fingerprints would be taken, if this was an operational scanner. 

After locating the scanner, I would like you to position four fingers of one hand (index, 

middle, ring, and little finger) on top of the scanner were you think the fingerprint image will 

be taken. Your fingers should be positioned so that none of them are touching a textured 

surface. They should only be on a smooth surface. 

Once you feel that your fingers are correctly on the platen, tell us. Afterwards, press down 

on the scanner, the scanner will indicate that the scan has begun. It will also indicate the 

scan is over. 

Throughout this process, I would like you to talk out loud about what is going on. So when 

you hear the locator tone, please tell me your impressions of it. Tell me about locating the 

scanner, placing your hand appropriately, and when the scan starts and when the scan ends. 

Your opinions on this process are very important to us and they will influence our future 

research in this area. 

After the scanning, I would like to play a few tones for you to get your opinions of them as to 

how effective they might be for locating biometric devices. 
NISTIR 7484 02/28/2008 

APPENDIX C 

Table 6 Participant Interview Responses: Fingerprint 

Participant

What cues would you 

recommend to help 

make the fingerprint 

process more 

independent or 

accessible? 

Visual 

Impairment

Tactile 

Cues 

Audio 

Cues 

Verbal 

Cues 

1 Recommended use of a 

mold that a person could 

feel and would help clue a 

visually impaired 

individual as to how to 

position their fingers for 

the most effective 

scanning. Participant 

indicated that this 

technique (molding tactile 

layouts) was useful for 

layouts for keyboards 

Totally 

blind and 

wears an 

opaque 

prosthetic 

shell over 

eyes 

X 

2 Recommended the use of 

some form of tactile 

surface that would 

accommodate hands of 

different sizes.. 

Blind 

X 

3 Recommended tactical 

guides, suggesting that the 

scanning surface have 

indentations that would 

indicate were the fingers 

Totally 

blind X 
should be placed. Another 

suggestion was that the 

scanning surface should 

have contrasting surfacetextures. The surface would 

be smoother were the 

fingers should be placed, 

or, the surface could have 

notches where the fingers 

should be placed. 

4 Recommended that we 

could train the individually 

impaired individual with 

how to place their hands. 

Additionally, the 

participant suggested that 

tactical/raised markings on 

the scanning surface would 

be helpful. Participant also 

suggested that the scanner 

should beep after its scan 

process is completed. 

Totally 

blind, one 

eye is 

artificial X X 

5 Recommended clear 

audible directions, a beep 

indicating completion of 

the scanning . Also the 

scanning surface should be 

larger and some form of 

tactile indications would be 

helpful. 

Totally 

blind and 

wears 

opaque 

prosthetic 

shells over 

eyes 

X X 

6 Recommended verbal 

directions, along with 

manual guidance of hands. 

Low vision, 

due to 

anaridia and 

glaucoma. 

X 

7 Recommended verbal 

directions, along with a 

Legally 

blind, but 

NISTIR 7484 02/28/2008 

X 
NISTIR 7484 02/28/2008 

small amount of manual 

guidance of hands. 

small 

amount of 

vision and 

could 

probably 

locate where 

to place 

hand on 

scanner 

8 No recommendations (this 

participant had some vision 

and could identify the 

scanning surface.) Sliding 

fingers over the scanning 

pad felt awkward but was 

accommodating.. 

Legally 

blind, 2300 

vision in one 

eye 

(glaucoma 

in this eye) 

and totally 

blind in the 

other 

9 This participant did not 

find the experience of 

using the digital scanner 

that difficult, but audio 

cues to indicate the end of 

the scanning process would 

be helpful . Concern was 

expressed about the 

required forms which were 

completely inaccessible. 

Totally 

blind, two 

artificial 

eyes 

X 

10 Recommended verbal cues. 

Also, multiple inputs such 

as both verbal and large 

imprints. 

Low vision 

suffers from 

strabismus 

(commonly 

known as 

cross-eyes) 

X X 
NISTIR 7484 02/28/2008 

APPENDIX D 

Table 7 Participant Interview Responses: Iris 

Participant How would you recommend that iris scanning be addressed? 

1 This participant is blind and wears an opaque prosthetic shell (something like 

contact lenses) which would prevent scanning of the iris. Iris scanning for the 

visually impaired would require very clear instructions such as look directly 

ahead and continue with the directional guides until the eyes are in scope. 

2 This participant had no suggestions 

3 This participant is blind, and the only way that the iris scanning might work 

would be to use a face mask or chin support. 

4 This participant is totally blind and one eye is artificial which would prevent 

scanning of that eye. However, with proper directions, his other eye would be 

scannable with appropriate directions 

5 This participant is blind and wears opaque prosthetic shells preventing 

scanning of the iris. 

6 This participant has low vision, due to anaridia and glaucoma and had no 

recommendations. 

7 No suggestions 

8 No suggestions 

9 This participant has two artificial eyes and was concerned about the design of 

systems that may prevent easy participation of individuals with eye injuries or 

missing limbs. 

10 This participant has low vision, due to strabismus (commonly known as crosseyes). Large visual aids and contrasting colors would be helpful.