In a method for operating a fingerprint sensor including a plurality of ultrasonic transducers and a presence sensor, the presence sensor proximate the fingerprint sensor is activated, where the presence sensor is for detecting interaction between an object and the fingerprint sensor. Subsequent to detecting interaction between an object and the fingerprint sensor at the presence sensor, a subset of ultrasonic transducers of the fingerprint sensor is activated, the subset of ultrasonic transducers for determining whether the object is a human finger, where the subset of ultrasonic transducers is proximate the presence sensor such that the subset of ultrasonic transducers and the presence sensor can concurrently interact with the object.