Picture of a stopwatch

Reaction Time

Paraphrasing Robert Benchley, we may say that there are two kinds of people in the world, those who believe there are two kinds of people and those who do not.   

Were you an orchid or a dandelion? Do you resemble a chimp or a bonobo?  And of course most of us fall between the extremes. We are tulips or, as it turns out, human.

Yet the story of the hare and the tortoise remains evergreen as a metaphor for the way we differ.  Though most of us fall in the middle when reaction times are measured, psychologists have been waiting at finish lines for a century and a half, timing us.


Baseball hitter swung too late.

BIO: Nerve signals were accurately timed before our mental operations. In 1850 Hermann von Helmholtz measured the speed of electrochemical impulses as they raced along nerves. His data have been updated many times; his method of investigation and the reasoning that accompanied it were as important as his data. You may have participated in a demonstration of his method in your psychology classes.

PSYCHO: Helmholtz’s method was important, not because it was the only way to measure the speed of the nerve impulse; rather, the logic impressed a psychologist later in the 19th century, Franciscus Donders, who applied it to measure mental operations.  His so-called subtraction method became the foundation for analyzing cognition with brain imaging.

Donders’s logic, apparently derived from Helmholtz’s procedure, was that if the stages of organizing a behavior occurred in sequence, then adding a stage should increase the reaction time by exactly the time required for the new stage.

It’s like building a wall with blocks: Each block you add to the end of the wall increases the length of the wall by exactly the width or length of the new block.

In brain imaging, brain activity is measured before the presentation of a stimulus—say, a picture—and then again during stimulus presentation, and the extra brain activity is attributed to processing the picture, using the cognitive subtraction method already described.

Are mental events just like blocks? A number of researchers would beg to differ. New models from Sternberg in 1969 and Grice in 1982 have taken a fresh look at these issues.

But reaction times supply useful information without considering “psychic acts”, as William James put it in his incomparable Principles of Psychology. (Scroll down to the section on “Reaction-Times”.)

Reaction times are one of the oldest, but still current, tools of the psychologist. They are task-sensitive and they comprise different components.

Incidentally, reaction times are related to so many behaviors that you can find lots of tests online. Here are a few:

Or just play catch a ruler for an enjoyable test. Reflexes are the fastest reactions. Consider escape in the copepod, for example. We can’t match it. Even when it comes to startle, we lose to a fly.

However, we can often improve with practice or heightened alertness. And if we’re not troubling to infer mental events that we can’t measure directly, ballpark figures for reaction times may turn up interesting generalizations: “The average reaction time for a visual stimulus is 200 to 250 ms; for hearing, 150 to 200 ms; and for touch, 130 to 170 ms.”

In fact, speaking of ballparks, hitting a fastball may involve reaction times that exclude the possibility of much thought at all. On the road, our habits may allow us to react with similar speed in applying the brakes. See how you do here and check your time against the generalization of a 200 or 250-millisecond reaction time for visual stimuli given above to see how influential the response task is.

Yet on the road, we’re giraffes. Our reaction times don’t match a race driver’s. Young athletes from the pit crew or another sport might come close, but F1 drivers are seemingly a breed apart* in skill, experience**, cognition and maybe in other ways***.

*And culturally a gender apart. If there is also a sex difference in race driving it may relate to a sex difference in the retrosplenial cortex, an area of the brain that may be particularly important for race driving, as it seems to support navigation.

Claims about sex differences can be needlessly provocative because the averages typically differ only slightly, they are influenced by experience as well as heredity, and they show that it’s dangerous to box us into types. Biology does matter, but so does culture. When we “type” people as male or female we tend to assume everyone in the same box has the same deviance. In fact, as one researcher put it, there is “tons of overlap“.

SOCIAL: Performing in front of an audience often improves performance, if the task is not too hard*. The phenomenon is called social facilitation. As this is written, the uncertain threat of a virus pandemic is emptying sports arenas and stadiums. Athletes are departing along with the fans, leaving us unable to compare the effect of an audience on, say batting averages.

As for the effect of an individual on a group, that’s easier. We all listen to jokes, and it’s obvious that a stand-up comic with a quick delivery makes the audience laugh in synch, with a reaction time of about a half-second. (Judge for yourself with comics about 50 years apart and see if it has changed in that time: Henny Youngman and Emily Heller.)

Laughs have a complicated structure, so timing their latency is not like timing knee jerks.

*If the task is too hard, performers focus too much on how they’re performing and they choke.

Overlapping height distributions for men and women

You can find more discussion of the statistics here. Still, some will say there are no differences, no real differences, while others argue that the differences are undeniable. There are anti-anti-difference arguments. Then there are the peacemakers

In the end, though, we shouldn’t apply group generalizations to ourselves without a lot of thought. Some folks try to predict behavior from genetically-influenced traits and claim to do it fairly well: criminal profilers, for example; divorce researchers; even physicists who study mobility, including reaction times. Even if their claims hold up, we should avoid applying their conclusions to our own behavior because of the ecological fallacy, which is the belief that group statistics can predict individual behavior.

**Note contrast in attention with average drivers.

***All sometimes lost in an instant instead of gradually.

Illustration credit: https://sugarandslugs.wordpress.com/2011/02/13/sex-differences/

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