Brian C. Stanton

Real-time feedback for usable fingerprint systems

Compared with traditional password and other identification methods, biometrics such as face, iris, and fingerprints for automatic personal identification and verification have many advantages, and are increasingly gaining popularity in all kinds of applications. As the technologies mature, the community has begun to realize that usability has great impact on the final accuracy and efficiency of a biometric system. Although research has shown that effective user feedback can improve the quality of the fingerprint images captured and user satisfaction, currently user feedback information of fingerprint devices used in real world applications is very limited. We design a rich, quality-driven interactive real-time user feedback mechanism for unattended fingerprint kiosk. The system aims to improve the quality of biometric samples during the acquisition process by feeding rich information back to the user instantaneously by measuring objective parameters of the image. The paper proposes an innovative, cost-efficient, real-time algorithm for fingertip detection, slap/thumb rotation detection, and finger region intensity estimation. The paper provides detailed information on the technical solution and its implementation. Preliminary results show that the methodology can potentially increase efficiency, effectiveness, and user satisfaction of a fingerprint biometric system.

Biometric Systematic Uncertainty and the User

Often biometric technology and system evaluators are concerned with capturing accurate performance estimates that predict performance for target populations of interest. Occasionally, predictions, and perhaps adjustments, for subpopulations based on convenient characteristics such as sex or age are examined. Few experiments have been performed to explicitly study the interaction of the user and the biometric system -how a users behavior, cognition, perception, and anthropometric qualities affect performance metrics and error estimates. This paper summarizes three studies performed in this emerging field of biometric usability. Each study focused on fingerprint recognition and the systematic uncertainty in system performance induced by different human factors. First, the effect of feedback and habituation on image quality is examined. Second, results from a study on the influence of the height of the surface upon which the fingerprint sensor is placed are presented. A summary of an experiment on the effect of instructional materials on the timing and error rates for a 10-print capture process closes the paper.

Effects of Scanner Height on Fingerprint Capture

Although the deployment of biometric technologies such as fingerprints is becoming more widespread, little attention is being paid to the human-computer interaction that such technologies involve. Most biometric systems employ both hardware and software measures to maximize the capture quality of the biometric data. The physical presentation of the biometric data by the participant to the system involves many anthropometric and ergonomic factors that have been largely ignored. This study examined the effect of the height of the sensor on the quality and the time required to collect fingerprints. User performance, both fingerprint quality and timing, was impacted by scanner height.

Optimal Size and Spacing of Touch Screen Input Areas

Touch sensitive displays have been implemented commonly as the simple interface to menu systems in information kiosks, but have the potential for use as the main interface to complex systems. The human factors necessary to design an optimal touch sensitive human computer interface have not been derived from an extensive base of empirical research. The available standards appear to have been developed originally for mechanical pushbutton switches. Two experiments were designed to evaluate the adequacy of the current standards for defining the size and spacing of the touch areas. The first experiment employed a Fitts Law paradigm to evaluate distance, size and touch accuracy. The second employed a telephone-type touch entry keypad allowing input speed and accuracy to be evaluated with the differing size and spacing. Active touch areas were manipulated in conjunction with the variations in size and spacing. The results of these experiments are compared to the existing standards and the validity of the current standards are discussed.

Usability Testing of Face Image Capture for US Ports of Entry

The requirements necessary for taking a successful face picture are arguably the least constrained of any biometric. The camera must be operational, and the subject must be illuminated sufficiently & facing the camera. Yet, a significant portion of the faces taken at US ports of entry are unusable for the purposes of automatic face recognition. In this paper, we consider the usability components of the face image capture process that contribute to the relatively high ratio of unusable images collected by United States Visitor and Immigrant Status Indicator Technology (US-VISIT). In addition, we introduce a general evaluation methodology - including the use of a simple image overlay - to quantify various characteristics of face imagery. The experimental context mimicked the point-of-entry environment, but with specific usability enhancements. The collected data suggests that these usability enhancements may be used to improve face image capture with equipment that is capable of capturing faces with a near-zero failure-to-enroll (FTE) rate.

How the subject can improve fingerprint image quality

Traditionally, the biometric field has viewed the subject as a passive source of the biometric sample rather than as an interactive component of the biometric system. But fingerprint image quality is highly dependent on the human–computer interaction and usability considerations of the acquisition system. Those factors impacting the acquisition of high-quality images must be identified, and real-time feedback for subjects to ensure acceptable quality images must be integrated into fingerprint capture systems. We report on a usability study that examined the influence of instructional materials on the user (subject) performance of a 10-print slap acquisition process. In addition, we also investigated the relationship of pressure and image quality as a mechanism to provide real-time feedback to the subject. The usability study included 300 participants who received instructions and interacted with the scanner. How information is provided to the subject on interacting with the fingerprint device does indeed affect image quality. The pressure findings are less conclusive; there was no clear relationship between image quality and pressure that could be exploited for feedback to the subject. However, a minimum pressure was required to initiate our capture process.

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

Despite the increased deployment of biometric technologies in United States government applications, not enough attention is being paid to the human factors that such technologies involve. The use of biometric applications will be unfamiliar to many users, who may neither understand nor be comfortable with the technology. Currently, U.S. Customs and Border Protection (CBP) Officers are critical in communicating and training users in the acquisition of fingerprints. Since user behavior can affect both the throughput of the system as well as the quality of the captured images, guidelines for developing interactions with biometric applications that increase throughput and image quality would be valuable. This study examines the effect of instructional modes on user performance. Posters were not as effective in providing instructions to users as video or verbal instructions.

Does the Angle of a Fingerprint Scanner Affect User Performance

As the deployment of biometric technologies such as slap fingerprint scanners has become more widespread in government applications there is an increased awareness of the human-computer interaction that such technologies involve. User behavior can impact operational system performance especially throughput and the quality of the collected biometric samples. This paper describes a study for the Department of Homeland Security that examined the impact on the time required to collect fingerprints and the quality of fingerprint images when fingerprint scanners are angled at tall counters to accommodate a broader range of visitors. Angling the fingerprint scanner had no impact on user performance.

Assessing Face Acquisition

The requirements necessary for taking a successful face picture are fairly straightforward. The camera must be operational, and the subject must be illuminated sufficiently, facing the camera and in focus. Yet, a significant portion of the facial photographs taken at United States ports of entry are unusable for the purposes of automatic face recognition. In this paper, we consider the usability components of the face image capture process that contribute to the relatively high ratio of unusable images collected by United States Visitor and Immigrant Status Indicator Technology (US-VISIT). In addition, we introduce a general evaluation methodology—including the use of a simple image overlay—to quantify various characteristics of face imagery. The experimental context mimicked the point-of-entry environment, but with specific usability enhancements. The collected data suggests that these usability enhancements may be used to improve face image capture with the current equipment. US-VISIT requested that the biometrics usability team at the National Institute of Standards and Technology (NIST) examine the current US-VISIT face image collection process to identify any usability and human factors that may improve the existing face image capture process. As such this study did not address other technologies or technology solutions. This report presents the results of a study that examined five usability and human factors enhancements to the current US-VISIT collection process: 1. the camera should resemble a traditional camera; 2. the camera should click when the picture is taken to provide feedback to the traveler that the picture is being taken; 3. the camera should be used in portrait mode; 4. the operator should be facing the traveler and the monitor while positioning the camera and 5. provide some marking on the floor (such as footprints) to indicate to the traveler where to stand for the photograph. The study was conducted as follows: first we visited and observed a representative operational setting (Dulles Airport) in order to understand the primary users and the context of use. Based on these observations we identified the 5 usability and human factors enhancements enumerated above that may improve the face image capture process. A usability study was designed that mimicked the operational process but incorporated the 5 enhancements and face images were collected from 300 participants. A visual inspection evaluation methodology based on an image overlay was used to quantify the various characteristics of face imagery based on the face image standards. Results from the visual inspection process compared …

Concepts of operations for robot-assisted emergency response and implications for human-robot interaction

In this paper we discuss a field study at Disaster City, Texas in March 2006. First Responders and robot developers tried out various concepts of operations in a number of disaster scenarios. Observations, video data, and questionnaire data were analyzed and based on these results, we propose some guidelines as well as some future research areas for human-robot interaction. In addition to the guidelines proposed as a result of our observations in this study, we include design implications from other literature, both laboratory and field studies.