What if I told you there’s a test that can tell you not only how clever you are, but how likely you are to suffer an untimely death?

Even in the unlikely event that you believed me, you’d probably think that the test was long and complicated, and cost a fortune.

If so, you’d be wrong. The test takes less than a minute and is free; you can take it online right here. It’s also very simple. All you have to do is press a button when the traffic light turns from red to green. You have five goes at the test, and the site will tell you your average. Go on, I’ll wait. Push the button.

So how did you get on? My average reaction time (i.e., the time it takes to press the button) was 0.309 seconds (i.e., 309 milliseconds [thousands of a second]). Were you faster or slower?

A study of around 5,000 Americans aged 20-59 found that those with slow reaction times were 25% more likely to die over the course of the study (15 years) than those with quicker reaction times. They were also 36% more likely to die of cardiovascular disease (heart attack, heart failure, stroke etc.).

Right now, you’re probably asking two questions: (1) “Do I have a ‘slow’ reaction time?” and (2) “Why are people who do more likely to die sooner?”

A ‘slow’ reaction time in this context means one of more than 300[1] milliseconds (0.300 seconds), which places me just – just – in the ‘slow’ category. But I’m not overly concerned, and, if you are in this category, neither should you be. For one thing, this online test isn’t perfect, and depends to some extent on the characteristics of your computer, mouse, keyboard, internet browser etc. (for example, I just did it again using the keyboard instead of the mouse, and scraped in at 292 milliseconds). For another, a 25% increased chance of dying within the 15-year follow-up period sounds worse than it is. In fact, because most people did not die in this period, the 25% increase associated with a slow reaction time amounts to an increase from around 7 deaths per 100 participants to 9 per 100. To put this 25% increase into perspective, a similar study found that (a) being a man and (b) smoking increased your chances of dying within a 14-year period by about 43% and 221% respectively.

But why are people with slower reaction times (slightly) more likely to die young? There are at least two possible reasons. First, many researchers have argued that your reaction time is a fairly direct measure of the integrity of your body and brain; essentially the extent to which it remains undamaged and well functioning. Second – and probably more importantly – your reaction time is also a good measure of your overall intelligence (something you can read more about in the book version of Psy-Q). And, yes, more intelligent people live longer, for all the boring reasons that you’d expect: They are more likely to exercise, go to the doctor and eat healthily, and less likely to smoke, drink and take drugs.

There’s also a third possible type of link between reaction time and mortality; albeit one that involves a scenario that is thankfully too rare to show up in these kinds of statistical analyses: car accidents. If the worst happens, the ability to react a few tenths of a second quicker might just make all the difference.

Because – to adopt a Hollywood mangling of an old English phrase – when it comes to reaction times, particularly in these types of extreme scenarios, there are two types of people: The Quick and The Dead.

This is a sample chapter in the style of Psy-Q by Ben Ambridge, forthcoming from Profile Books (UK) and Penguin (US). For details click here

Sources:

Hagger-Johnson, G., Deary, I. J., Davies, C. A., Weiss, A., & Batty, G. D. (2014). Reaction Time and Mortality from the Major Causes of Death: The NHANES-III Study. PLOS ONE, 9(1), e82959.

Deary, I. J., & Der, G. (2005). Reaction time explains IQ’s association with death. Psychological Science, 16(1), 64-69.]

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.

Photo credit: Paweł Marynowski

[1] “Slow” here means 1 Standard Deviation (58.0ms) above the mean (242.7ms). 242.7+58.0=300.7ms.