Psychologists have been measuring reaction times since before psychology existed, and they are still a staple of cognitive psychology experiments today. Typically psychologists look for a difference in the time it takes participants to respond to stimuli under different conditions as evidence of differences in how cognitive processing occurs in those conditions. Galton, the famous eugenicist and statistician, collected a large data set (n=3410) of so called ‘simple reaction times’ in the last years of the 19th century. Galton’s interest was rather different from most modern psychologists – he was interested in measures of reaction time as a indicator of individual differences. Galton’s theory was that differences in processing speed might underlie differences in intelligence, and maybe those differences could be efficiently assessed by recording people’s reaction times.…