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The reaction time problem

posted by Tim Carmody   Jul 03, 2018

reaction time over time.jpg

Francis Galton, a Victorian eugenicist and statistician, was obsessed with measuring reaction time as a proxy for general intelligence. In 1885, 1890, and 1892, he collected “data on the sensory, psychomotor, and physical attributes of 1,639 females and 4,849 males.” Eventually, though, reaction time gave way to other questionable measurements of generalized intelligence like IQ tests and scholastic aptitude scores, so most of us don’t keep track of our reaction times, if we’ve ever had it measured.

Here’s the thing, though — everyone who’s tried to repeat Galton’s experiments in the 20th and 21st century, across populations, varying the equipment used and the measurement process taken, etc., has never been able to get reaction times as fast as what Galton measured. IQ scores have generally risen over time; reaction times have slowed down. It’s a matter of milliseconds, but the effect is large: about 10 percent. It is quite possible that young adults in 19th century Great Britain were just plain faster than us.

Tom Stafford, writing at Mind Hacks, has some helpful caveats:

What are we to make of this? Normally we wouldn’t put much weight on a single study, even one with 3000 participants, but there aren’t many alternatives. It isn’t as if we can have access to young adults born in the 19th century to check if the result replicates. It’s a shame there aren’t more intervening studies, so we could test the reasonable prediction that participants in the 1930s should be about halfway between the Victorian and modern participants.

And, even if we believe this datum, what does it mean? A genuine decline in cognitive capacity? Excess cognitive load on other functions? Motivational changes? Changes in how experiments are run or approached by participants? I’m not giving up on the kids just yet.