Iris pigmentation and fractionated reaction and reflex time.
Recent investigations indicate that an iris pigmentation-motor behavior exists, but may be limited to the reaction time component of a motor task. The absence of differences in peripheral nervous conduction (Wolf and Landers, 1978) suggests that a central nervous system mechanism may be operating, possibly dependent on the characteristics of neuromelanin or catecholamine turnover. Experiment 1 tested this notion by fractionating simple reaction time into the premotor and motor components by electromyography. ANOVA revealed that dark-eyed subjects had faster total reaction times and premotor times, but only the premotor time component approached significance (p < 0.07). Experiment 2 fractionated patellar reflex time of light-eyed and dark-eyed subjects into reflex lagency and motor components. There were no eye color differences for any of the reflex time measures. The results of Experiments 1 and 2 support a central nervous system explanation for the iris pigmentation-reaction time phenomenon.
D001921:Brain / Q000502:physiology; D004576:Electromyography; D005127:Eye Color; D006801:Humans; D008297:Male; D010525:Peripheral Nerves / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012018:Reflex / Q000502:physiology; D012026:Reflex, Stretch; D009435:Synaptic Transmission