This laboratory experiment was designed to compare reaction times to brake signals when they appear with red or yellow turn signals. The subject's task was to respond as quickly as possible to the onset of peripherally presented brake lamps, while engaged in a central tracking task. There were three lamp conditions: brake lamps alone, brake lamps while turn signal was on, and a turn-signal lamp alone. The results showed that yellow turn signals, in comparison to red turn signals, led to significantly shorter reaction times to brake signals.