Under the wrong conditions, 'stop' could mean'go faster' to an autonomous car. A new study led by the University of Washington found that the type of computer brain set to be used in autonomous cars could be fooled into thinking a Stop sign is a 45 mph Speed Limit or other sign by adding just a little graffiti. The researchers peppered one Stop sign with a few black and white blocks, and used stickers to make another read "Love Stops Hate." In both cases, the deep neural network processing images fed to it by a camera misread the signs most of the time, even though they retained their octagonal shape and red background color. Another test simulated a slightly faded right turn arrow, which the computer often thought was a Stop sign or added lane sign, but which a human would have no trouble identifying.