Biometrics and Usability

The User and Biometric System Uncertainty

Mary Theofanos

International Workshop on Usability and BiometricsJune 23- 24, 2008

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The field of biometrics has tested, measured and reported performance statistics independent of the user

Error Bounds are defined as combination of:

• uncertainty resulting from random effect• uncertainty resulting from systematic effect

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User Characteristics Age Gender Height Experience Ability Perception

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Biometric System Factors

Anthropometrics Affordance Instructions Accessibility

Can we link the systematic uncertainty of fingerprint quality and performance metrics to human factors?

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Habituation Study found a number of human factors that influence quality

Age: Younger participants submit higher quality images than older participants

Gender: Women’s images, on average, are of poorer quality than men’s

Feedback ◦Habituation has no influence without

feedback◦Older participants left higher quality images

over time with feedback

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Anthropometrics: Effect of Sensor Height on qualityImage quality: All fingers are sensitive to height except

Right index finger Thumbs are more sensitive to height than

slaps Left slap is more sensitive than right slap Drop in quality from individual thumbprints

to simultaneously captured thumbprints Consistently able to provide higher quality

prints for work surfaces lower than 42 inches (107 cm)

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Anthropometrics: Effect of Sensor Height on Efficiency

Time (Efficiency) Counter height of 36 inches (91cm) yields

fastest performance Most efficient capture sequence starts with

right hand

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Poster Participants: took significantly longer to complete the 10-print collection process made significantly more errors only 56% were able to successfully complete the fingerprinting process left the poorest quality images using NFIQ.

Verbal and video instructions

performed equally well

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Operators are critical to the acquisition process

Operators are able to assist individuals to overcome the deficits of the instructional materials

With operator assistance 98% of participants were able to successfully complete the fingerprint process

Verbal instructions were most preferred by participants

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What about counter height and angle of the fingerprint scanner ?

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1010We have demonstrated a link between human factors quality and performance metrics

At BCC last fall Jim Wayman stated that:

Laboratory results are not a good predictor of “real-world” performance

Systematic uncertainty attributable to uncontrolled variability in human factors

Improving biometrics will require emphasis on human factors not the purely “technical” aspects