The International Organization for Standardization, Technical Committee 22, Subcommittee 13, Working Group 5 was given the task of determining which symbols should be proposed for standardization for fifteen controls, indicators and telltales. A test was devised in which three different symbols for each given control, indicator or telltale could be appraised by licensed drivers in a simulated driving situation. Data from 2593 licensed drivers from France, Germany, the United Kingdom, and the United States were obtained and statistically treated. The procedure and results are herein reported. On the basis of these results, symbols for 12 controls, indicators, and telltales were proposed as standards.