1. A subject monitoring pulse oximetry system for updating a display rate for a subject, comprising: a pulse oximetry sensor configured to detect light attenuated by the subject and generate a photoplethysmographic (PPG) signal based on the detected attenuated light; a pulse oximeter coupled to the pulse oximetry sensor; and a display coupled to the pulse oximeter, wherein the display is configured to display the display rate for the subject, wherein: the pulse oximeter is configured to: determine a value indicative of a physiological rate of the subject; determine a first metric based on the PPG signal; perform a filtering calculation based on the PPG signal to generate a filtered PPG signal, wherein the filtering calculation comprises a high-pass filter having a cut-off set at a frequency higher than a frequency corresponding to the value indicative of the physiological rate of the subject; determine a second metric based on the filtered PPG signal; qualify the value indicative of the physiological rate of the subject based on the first and second metrics; and update the display rate on the display based on the qualified value indicative of the physiological rate.