Psychologists have been measuring reaction times since before psychology existed, and they are still a staple of cognitive psychology experiments today. Typically psychologists look for a difference in the time it takes participants to respond to stimuli under different conditions as evidence of differences in how cognitive processing occurs in those conditions.
Galton, the famous eugenicist and statistician, collected a large data set (n=3410) of so called ‘simple reaction times’ in the last years of the 19th century. Galton’s interest was rather different from most modern psychologists – he was interested in measures of reaction time as a indicator of individual differences. Galton’s theory was that differences in processing speed might underlie differences in intelligence, and maybe those differences could be efficiently assessed by recording people’s reaction times.
Galton’s data creates an interesting opportunity – are people today, over 100 years later, faster or slower than Galton’s participants? If you believe Galton’s theory, the answer wouldn’t just tell you if you would be likely to win in a quick-draw contest with a Victorian gunslinger, it could also provide an insight into generational changes in cognitive function more broadly.
Reaction time [RT] data provides an interesting counterpoint to the most famous historical change in cognitive function – the generation on generation increase in IQ scores, known as the Flynn Effect. The Flynn Effect surprises two kinds of people – those who look at “kids today” and know by instinct that they are less polite, less intelligent and less disciplined their own generation (this has been documented in every generation back to at least Ancient Greece), and those who look at kids today and know by prior theoretical commitments that each generation should be dumber than the previous (because more intelligent people have fewer children, is the idea).
Whilst the Flynn Effect contradicts the idea that people are getting dumber, some hope does seem to lie in the reaction time data. Maybe Victorian participants really did have faster reaction times! Several research papers (1, 2) have tried to compare Galton’s results to more modern studies, some of which tried to use the the same apparatus as well as the same method of measurement. Here’s Silverman (2010):
the RTs obtained by young adults in 14 studies published from 1941 on were compared with the RTs obtained by young adults in a study conducted by Galton in the late 1800s. With one exception, the newer studies obtained RTs longer than those obtained by Galton. The possibility that these differences in results are due to faulty timing instruments is considered but deemed unlikely.
So the difference is only ~20 milliseconds (i.e. one fiftieth of a second) over 100 years, but in reaction time terms that’s a hefty chunk – it means modern participants are about 10% slower!
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.
References:
- Irwin, W. S. (2010). Simple reaction time: it is not what it used to be. American Journal of Psychology, 123(1), 39-50.
- Woodley, M. A., Te Nijenhuis, J., & Murphy, R. (2013). Were the Victorians cleverer than us? The decline in general intelligence estimated from a meta-analysis of the slowing of simple reaction time. Intelligence, 41(6), 843-850.
- Woodley, M. A, te Nijenhuis, J., & Murphy, R. (2015). The Victorians were still faster than us. Commentary: Factors influencing the latency of simple reaction time. Frontiers in human neuroscience, 9, 452.
Mind Hacks 
Average human height has since changed by the same 10%, and nerve conduction velocity remained the same.
Intriguing suggestion! Makes sense – if arms are 10% longer than responses will take 10% longer to travel down them. But are they? Somebody *must* have looked at the effect of height on RT
Sadly, they have and found no strong relation http://www.jstor.org/stable/10.5406/amerjpsyc.123.1.0039
“One study, with Australian adults, found height to be unrelated to RT when age, gender, and education were controlled (Anstey, Dear, Christensen, & Jorm, 2005), and the other study, with American adults, found no relationship between RT and height (Kilburn, Thornton, & Hanscom, 1998). Although Taimela (1991) found in a Finnish sample that height was significantly associated with RT, height accounted for far less than 1% of the variance in RT.”
It is somewhat strange that the height (or the arm length) has no effect. Where does the extra conduction velocity come from? Regarding visual stimuli, there is one substantial difference between 1890 and today’s Western populations that is virtually impossible to correct for: exposure to artificial (electrical) lighting. We got so inured to lights instantly turning on or off that the “startle reflex” triggering a quick motor reaction as a response to any visual stimulus is largely gone.
Wouldn’t physical fitness affect this? Blood flow? I can’t believe the average Victorian experienced *less exercise than we do today.
I would think that reaction time has more to do with physical fitness than anything else. During Victorian times, most people had highly physical jobs and lifestyles. One would assume they would have been physically fit. But they didn’t have much in the way of education, intellectual development, and neurocognitive stimulation.
There is no reason to assume a connection between reaction time and intelligence, as compared across historical periods and between societies. Traditional hunter-gatherers probably have amazingly high levels of reaction time and yet would measure miserably low on IQ tests, largely because of the relationship of abstract thinking and fluid intelligence.
I don’t see any real mystery here. The only question is how physically fit was the average Victorian person.
Here is where my thought was going. We are healthier in many way than past populations, but not in all ways. For example, present society is highly stressful as seen with how increasing inequality and urbanization is correlated with increasing mental illness, including severe psychiatric conditions such as psychosis and schizophrenia. One would presume that mental illness is indicating deeper problems going on within the body itself, as stress affects not only the mind but everything else as well.
I put this comment in the wrong place. It was meant to be a second response to Ted below.
The most satisfactory explanation I have found for this is selection bias: http://slatestarcodex.com/2013/05/22/the-wisdom-of-the-ancients/
This is really convincing – thank you
Maybe the reaction times have become slower because people have become more intelligent? After all, it is plausible that a simpler brain would react faster.
I read somewhere’s that the Victorian age people were much stronger and I think they used the example of how heavy the sledgehammers they used were, the average western person may have less strength even if the work out.
What is cognitive about a raw reaction time? If anything, heightened cognition (identification, evaluation, reasoned response, etc.) would seem to muck up the process. My cat reacts extremely quickly.
Reaction time is like a general indicator of health. Physical health is, of course, related to neurological health. Many things would decrease health (stress, parasites, toxins, malnutrtion, etc) and one of the most obvious signs of this would be decreased reaction time. But reaction time by itself doesn’t really tell us anything.
Here’s my recent contribution:
https://www.tandfonline.com/doi/abs/10.1080/00221325.2018.1469113
Evidence of a Flynn Effect in Children’s Human Figure Drawings (1902–1968)
ABSTRACT
The Flynn effect is the long-term trend for scores on tests of cognitive ability to increase across cohorts. Several samples of children’s human figure drawings, published in 1902, 1926, 1963, and 1968, are examined for evidence of a Flynn effect. Results show that larger percentages of children draw more complete human figures over the course of the 20th century.
Second Factor: Poor nutrition. Modern diets have become severely deficient in numerous nutrients. For example, 97% of the population in the U.S. is deficient in potassium intake. Magnesium intake is also deficient in the vast majority of people. Potassium and magnesium are necessary to run the sodium-potassium pumps in cells such as nerve cells and muscles that allow the cells to perform their activities. For nerve cells, this is the conduction of signals. For muscle cells, this is contraction. So these deficiencies which were much less in the 1800s accounts for another decrement in reaction time of modern humans versus humans in the 1800s.
First factor: More people today have hypothyroidism or subclinical hypothyroidism – now about 40% of the population – compared to the 1800s.
Hypothyroidism slows down your reaction times, reflexes, nerve conduction speed, thought speed.
In the 1800s, we had no antibiotics nor vaccines. Generally, hypothyroidism increases the likelihood of death by causes such as infections in childhood. But in the 1900s, antibiotics were developed. This allowed people who were hypothyroid to survive. And the gene for hypothyroidism has as a consequence survived and spread through the population. In contrast, in areas of the modern world with poor medical care such as in Africa, the incidence of hypothyroidism is much lower.
So the population in the 1800s is skewed to have less hypothyroidism or subclinical hypothyroidism compared to modern times. And consequently, the population as a whole had faster reaction times than the modern population.
Further research find that there are “intervening studies”.
Ref: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4374455/
Some studies postulate increasing industrial toxicity, e.g., radio transmissions.
Neglected areas of industrial toxicity I postulate, are prenatal X-rays and ultrasound, clearly be a source of high stress and fetal damage according to most modern studies of prenatal radiation.
Ref: http://www.harvoa.org/chs/pr/dusbk1det.htm
see this:
https://www.sciencedirect.com/science/article/pii/S0160289613001281