Note. If you have calculated the RT mean and RT variance based on data measured in milliseconds, you need to take some care when transforming these quantities to seconds. The RT mean in seconds is obtained from the RT mean in milliseconds by simply dividing by 1000, but the RT variance in seconds-squared is obtained from the RT variance in milliseconds by dividing by 1000 times 1000 (i.e., 1,000,000).
Wagenmakers, E.-J., van der Maas, H. L. J., & Grasman, R. P. P. P. (2007). An EZ-diffusion model for response time and accuracy. Psychonomic Bulletin & Review, 14, 3-22.