video footage (none of the videos were the same as the ones the volunteers watched) to select the clips that were most similar. The authors have uploaded demos comparing the watched and the computer-estimated videos. Lie detector Brain-reading has been suggested as an alternative to polygraph machines as a form of lie detection. Another alternative to polygraph machines is blood oxygenated level dependent functional MRI technology (BOLD fMRI). This technique involves the interpretation of the local change in the concentration of oxygenated hemoglobin in the brain, although the relationship between this blood flow and neural activity is not yet completely understood. Another technique to find concealed information is brain fingerprinting, which uses EEG to ascertain if a person has a specific memory or information by identifying P300 event related potentials. A number of concerns have been raised about the accuracy and ethical implications of brain-reading for this purpose. Laboratory studies have found rates of accuracy of up to 85%; however, there are concerns about what this means for false positive results among non-criminal populations: "If the prevalence of "prevaricators" in the group being examined is low, the test will yield far more false-positive than true-positive results; about one person in five will be incorrectly identified by the test." Ethical problems involved in the use of brain-reading as lie detection include misapplications due to adoption of the technology before its reliability and validity can be properly assessed and due to misunderstanding of the technology, and privacy concerns due to unprecedented access to individual's private thoughts. However, it has been noted that the use of polygraph lie detection carries similar concerns about the reliability of the results and violation of privacy. Human–machine interfaces Brain-reading has also been proposed as a method of improving human–machine interfaces, by the use of EEG to detect relevant brain states of a human. In recent years, there has been a rapid increase in patents for technology involved in reading brainwaves, rising from fewer than 400 from 2009–2012 to 1600 in 2014. These include proposed ways to control video games via brain waves and "neuro-marketing" to determine someone's thoughts about a new product or advertisement. Emotiv Systems, an Australian electronics company, has demonstrated a headset that can be trained to recognize a user's thought patterns for different commands. Tan Le demonstrated the headset's ability to manipulate virtual objects on screen, and discussed various future applications for such brain-computer