time discrimination performances were examined using either a steadily presented or a heterochromatic luminance flickering visual standard-time-interval stimulus to address certain questions : 1. are individual differences in time perception reliably observed across durations of less than and greater than one second? 2. what is the relationship between individual differences in time perception and performance on nontiming cognitive tasks that measure processing speed, accuracy, and short term memory? 3. what is the effect of increasing pacemaker speed on time perception and does it vary across individuals who have a low or high sensitivity to time differences?--abstract.