The Biometric Tendency Recognition and Classification System is a software application that continuously measures a participant's physiological responses to a given image and runs a statistical classification algorithm on the measured data that then classifies the participant into one of four categories: passive, aggressive, loyal and subversive. The system is part of an interactive art project that explores issues of authority, privacy and security in relation to biometric technologies. In this paper, we demonstrate the development of this system that exemplifies the use of biometrics within the context of art. Categories and Subject Descriptors J.5 [Arts and Humanities]: fine arts. General Terms Algorithms, Performance, Design, Experimentation, Security, Human Factors. Keywords Biometrics, Biofeedback, Physiological Monitoring, Interactive Art, Machine Learning, K-Nearest Neighbor.