1. A method for conducting pharmaceutical drug testing to ascertain the efficacy or toxicity of a candidate target drug comprising the steps of: administering the target drug to a test subject and, measuring the reaction of the test subject to the administration of the target drug utilizing smooth pursuit cognitive testing, wherein the smooth pursuit cognitive testing includes: presenting a smoothly moving object on a screen; using one or more cameras to detect gaze direction of one or more eyes of the test subject while the test subject visually tracks the smoothly moving object presented on the screen, and determining cognitive performance of the test subject in accordance with the test subject's performance in visually tracking the smoothly moving object presented on the screen.