Abstract: An interactive automatic system and technique for measuring and training of mental ability. In the illustrative embodiment, the invention is implemented on a computer which automatically presents a variety of visual and auditory stimuli. The system then measures reaction to the stimuli, adjusts certain stimulus parameters, and provides scores in response thereto. The scores are tabulated and displayed for analysis. In particular embodiments, the invention tests for physical reaction time, perceptual awareness thresholds, attention level, speed, efficiency and capacity of information processing by the brain and elementary cognitive processes, including memory, memory access and decision-making speed. The invention measures, identifies and quantifies noise in the subject's brain and elementary cognitive processing system, and the information exchange rate between the subject's left and right brain hemispheres.