Science / Medicine : IQ Linked to Neural Quickness

Researchers have long wondered what creates high intelligence. Is it the number of cells in the brain, or perhaps the manner in which the individual cells are connected to each other? Neither, according to UC Berkeley psychologist Arthur R. Jensen. Instead, it is the speed with which an electrical signal can pass through the cells, the so-called neural conduction velocity.

Jensen and zoologist T.E. Reed of the University of Toronto tested 147 Berkeley undergraduates, measuring the time it took for an impulse to travel from the retina in the eye to the visual cortex in the rear of the brain, a process that typically takes 20 to 100 thousandths of a second. They found that the faster the neural conduction velocity, the higher the measured IQ.

“Our study is the first one to show a correlation between IQ and neural conduction velocity in perfectly normal individuals,” he said. But he noted that speed alone does not account for all the variation among individuals’ IQs.