A wearable computing device, comprising: an input device (124, 126) configured to receive input for interacting with a display coupled to the wearable computing device; an infrared trip sensor configured to provide an output that is indicative of whether the wearable computing device is being worn, wherein the infrared trip sensor is configured to be operated between nosepads (123a,123b) of the wearable computing device and to detect disruptions in an infrared beam produced between the nosepads (123a,123b); a detector configured to image an environment of the wearable computing device; a computing system; and instructions stored in a memory of the computing system and executable by at least one processor of the computing system to perform functions comprising: receiving an output from the infrared trip sensor, based on the received output, determining a first power state for the computing system, determining that the first power state is a different power state than an existing power state of the computing system, and in response to determining that the first power state is a different power state than the existing power state, modifying an operating state of the computing system and modifying an operating state of the detector of the wearable computing device configured to image an environment of the wearable computing device. an input device (124, 126) configured to receive input for interacting with a display coupled to the wearable computing device; an infrared trip sensor configured to provide an output that is indicative of whether the wearable computing device is being worn, wherein the infrared trip sensor is configured to be operated between nosepads (123a,123b) of the wearable computing device and to detect disruptions in an infrared beam produced between the nosepads (123a,123b); a detector configured to image an environment of the wearable computing device; a computing system; and instructions stored in a memory of the computing system and executable by at least one processor of the computing system to perform functions comprising: receiving an output from the infrared trip sensor, based on the received output, determining a first power state for the computing system, determining that the first power state is a different power state than an existing power state of the computing system, and in response to determining that the first power state is a different power state than the existing power state, modifying an operating state of the computing system and modifying an operating state of the detector of the wearable computing device configured to image an environment of the wearable computing device. receiving an output from the infrared trip sensor, based on the received output, determining a first power state for the computing system, determining that the first power state is a different power state than an existing power state of the computing system, and in response to determining that the first power state is a different power state than the existing power state, modifying an operating state of the computing system and modifying an operating state of the detector of the wearable computing device configured to image an environment of the wearable computing device.