mary theofanos nist 301 975-5889 mary.theofanos@nist

Biometrics and Usability

HFES October 5, 2007

1

Mary TheofanosNIST

301 [email protected]

May 23, 2007

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.

Ten-Print Fingerprint Capture: Effect of Instructional Modes on User Performance

mailto:[email protected]

Biometrics and UsabilityHFES October 5, 2007

Why perform the study?

DHS and US-VISIT are transitioning from 2 prints to 10-prints

Visitors are not familiar with the 10-print process

Throughput and image quality are critical


Three Goals of the study

To Understand:

1. How instructional modes affect the user performance

2. How long it takes to capture a 10-print image

3. What types of errors occur in this process


Experimental Design

Instructional Modes Participants Leading HandRight Left

Verbal

Poster

Video

100

100

100

50 50

50 50

50 50

Timing Data and Errors


Three Instructional Modes

Read by the Test Facilitator:

Step #1: When the right most light starts flashing green; place your right four fingers (demonstrate what four fingers) on the scanner and press down. Hold your fingers in place until the green light stops flashing

Step #2: When the left most light starts flashing green; place your left four fingers (demonstrate what four fingers) on the scanner and press down. Hold your fingers in place until the green light stops flashing Step #3: When the center light starts flashing green; place your 2 thumbs (demonstrate thumbs side by side) on the scanner and press down. Hold your fingers in place until the green light stops flashing. Would you like me to repeat the instructions?

1st Mode: Verbal


2nd Mode: Poster


3rd Mode: Video

Video


Procedure

Give papers to operator

Fingerprint Collection

Receive Instructions


Who were the participants?

300 Adults◦ 151 women and149 men◦ Age ranged from 18 years to 75 years old◦ 265 right handed, 31 left handed, 2 ambidextrous◦ Height ranged from 4’ 6” to 6’ 9”◦ Fingerprint experience: 70 % inked 9.7% electronically


Event Timeline10

Time

Participant enters room

Participant is ready

Participant places hand down

Participant removes hand

Capture initiated. Light goes on.

Scanner detects hand down

Capture repeated if needed (error)

Light goes off. Scanner looks,for hand up.

Next Hand (3X)

First image is captured.

Instructions are presented

(All times measured in seconds)

Instructions

31.27 29.60

65.34 58.84 < .01

86.93 81.05

Mean Median p

Video

Verbal

Poster p < .01

p < .01

p < .01

imeTotalT

145.67126.85

151.73129.32 < .01

163.22152.18

Mean Median p

Video

Verbal

Poster p < .01

p > .05

p < .01

p

ession EndParticipant Readyto S

114.40 91.50

86.39 65.00 < .01

76.29 65.00

Mean Median p

Video

Verbal

Poster

> .05

1st HandDowntoTask End

64.13 58.50

48.21 45.00 < .01

50.87 46.00

Mean Median p

Video

Verbal

Poster

p > .05


Results : Efficiency

Method Participants Mean (sec) Median (sec)

Poster 52 64.13 58.5

Verbal 85 48.21 45.0

Video 85 50.87 46.0

Time for Successful Trials


Results : Effectiveness

Method Participants Mean Errors Median Errors

Poster 52 64.13 58.5

Verbal 85 48.21 45.0

Video 85 50.87 46.0

Number of Errors per Instructional Method


Results : Satisfaction

1. The information provided was effective in helping me complete the fingerprint process.

2. The information provided clearly described the fingerprint process.

3. The information provided was confusing.4. It was clear which hand was to be scanned first.5. The order of fingerprint capture was clear.6. It was clear how to position your hand on the

sensor7. It was clear when to remove your hand.

Survey Questions included:


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HFES October 5, 2007Biometrics and Usability

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Instructions are significant factors for performance and quality

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Poster Participants: took significantly longer to complete the 10-print

collection process made significantly more errors only 54% were able to successfully complete the

fingerprinting process left the poorest quality images using NFIQ.


15


15


Verbal instructions were rated highest

Poster was rated the lowest

Verbal and video instructions performed equally well

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Observations on methodsPoster:

◦ Felt poster offered too much information ◦ Common problem: removed their hand before capture had

taken place◦ Spent less time viewing the instructions than other 2

methodsVerbal:

◦ Overwhelmingly stated that clearly described the tasks ◦ Problems were due to lack of visual preparation and

difficulty with hand placement◦ Implied that the operator would assist them through the

processVideo:

◦ Generally performed well◦ Difficult to judge the timing of the lights ◦ Encouraged subjects to pay attention

"initially lights did not mean anything"

“label the lights on the

machine. Left and Right”

Should fingers be centered on the

scanner? The less you have to think

the better.


17


17


Operators were able to assist: Individuals to overcome the deficits of

the instructional materialsOn a second try with operators help: 98% of the participants who received

the poster were able to successfully complete the fingerprint process

Operators are critical to the acquisition process

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Language Independence is Key In the Operational Environment

Poster is error prone and impacts quality Verbal instructions are delivered to

visitors individually Video instructions can be presented to

visitors all at once◦ Provides optimum capture times◦ Low-error incidence◦ Reasonable quality

Video my be more conducive to the operational environment


Check out our website:

http://zing.ncsl.nist.gov/biousa/

http://zing.ncsl.nist.gov/biousa/

mary theofanos nist 301 975-5889 mary.theofanos@nist

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