Abstract: There is provided a system for automatically sensing the activities of an animal within a confined space. The system generally includes a containment assembly having top and side portions within which an animal may be confined. The system also includes an infrared light matrix subsystem for sensing the animal's position within the containment assembly relative to a first plane; an ultrasonic phase shift subsystem for sensing animal's position change within the containment assembly relative to a second plane; as well a decoding and interface circuit subsystems coupled to both the infrared light matrix and ultrasonic phase shift subsystems to perform the necessary decoding and input/output interface functions. The infrared light matrix subsystem is formed by a plurality of infrared transmitter and receiver pairs preferably attached to the side portions of the containment assembly and controlled by a single-chip microcomputer.