The present invention involves new interventional methods for reducing gastric volume, and thereby treating obesity. The method includes the steps of: assigning a value to a specified program or a time slot of a specified channel; receiving, at a central data system, data reflective of the specified program or specified time slot that the viewer watched or intends to watch; storing the assigned value in a viewer account; and interacting with the viewer. The P and S components are confined by sides of the splitter and the prism, respectively, by Total Internal Reflection, thereby achieving high efficiency without increasing the size of the optical components from that of lower efficiency, prior art polarization converters.