Patrick, A.S. (2004) Usability and acceptability of biometric security systems.
Abstract of a presentation at Financial Cryptography Conference (FC04), February 9-12, Key West FL.
Biometrics are receiving a lot of attention because of the potential to increase the accuracy and reliability of identification and authentication functions. A lot of research has been done to assess the performance of biometric systems, with an emphasis on false acceptances and rejections. Much less research has been done on the usability and acceptability of biometric security systems. A number of factors are increasing the usability of biometric devices. The sensors are getting smaller, cheaper, more reliable, and designed with better ergonomic characteristics. The biometric algorithms are also getting better, and many systems include features to train the users and provide feedback during use. In addition, biometric devices are being integrated into associated security systems, such as access control and encryption services, to provide a seamless environment.
There are still a number of usability concerns, however. The accuracy of many biometric systems is still not high enough for some applications (i.e., matching against a very large database). Also, there is often a negative relationship between the accuracy of a biometric system and the convenience for use, with the most accurate systems (e.g., DNA, Iris, Retina) being the most awkward to use. Biometric devices also have continuing problems handling users with special physical characteristics, such as faded fingerprints, leading to high "failure to enroll" rates.
Concerning the acceptance of biometric security systems, factors that are making the systems more acceptable include technical interest, concerns about identity theft, government border-control initiatives, and the opportunity to reduce memory demands by replacing memorized passwords. Research has shown, however, that users are still wary of accepting biometrics because the benefits are not always evident, and the possibilities for misuse and privacy invasions are large and not understood. Nevertheless, a recent survey of Canadian citizens  found that 80% of the respondents think that biometric systems will be commonly used in the next 10 years.
Overall, widespread use of biometrics in security systems faces a number of fundamental challenges, not the least of which is that a biometric characteristic is not a secret, so there is always a risk of it being copied or forged. Including "vitality tests" that ensure the biometric is offered by a living person will be crucial to avoid these problems. Managing privacy impacts and ensuring personal control of biometric use will also be very important for promoting acceptance.
 Citizenship & Immigration Canada: Tracking public perceptions of biometrics. 2003. http://www.cic.gc.ca/english/press/03/poll-biometrics-e.pdf