Techniques are described for use with a wide range of consumer and other electronic devices to facilitate a user's control of such features as volume, as well as song, channel or page selection, depending on the application. A method includes emitting light out of a module, receiving signals from light detectors in the module, wherein the signals represent, at least in part, light reflected by a person's finger or other object passing in front of the light detectors, detecting movement of the person's finger or other object based on the received signals, and controlling a feature of a device in response to the detected movement.