1. A subject monitoring system for processing physiological information of a subject, comprising: a pulse oximetry sensor configured to generate a physiological signal, wherein the pulse oximetry sensor detects light attenuated by the subject; and a pulse oximeter coupled to the pulse oximetry sensor, wherein the pulse oximeter is configured to: select a first segment of the physiological signal comprising a plurality of values; select multiple segments of the physiological signal, each comprising a plurality of values, wherein the multiple segments are each shifted in time from the first segment by a unique lag; determine multiple correlation values between the first segment and the multiple segments; analyze the first segment and the multiple segments to determine a plurality of metric values; determine correlation information based on the multiple correlation values and based on the plurality of metric values; determine a physiological rate of the subject based on the determined correlation information; and display the physiological rate of the subject on a display.