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Reaction speed tests are very old. Actually they form part of what we could call the beginning of Psychology as a science. Because it was the famous psychophysicist Galton who in the 19th century started to perform mechanical experiments around cognition, and one of them was about how fast people would respond to stimuli.
A lot has changed in Psychology ever since, but reaction speed tests have only but gained a foothold as one of the most objective and powerful cognitive measures. According to the current models of intelligence, specially the CHC model, reaction speed is a highly valuable ability which is indicative of intelligence. Under the CHC model specifically, reaction speed is an ability unto itself, a broad ability, that correlates pretty well with the IQ of a person.
Health and speed
Why there is such a strong connection it is not so clear, but we now know that reaction speed is highly related with the capacity and specially the health of the brain. Studies have systematically found that the longer the response time of a person is, the more chances there are of that person having some kind of disease or neurological issue. In fact, many diseases, like Alzheimer, and other damaging behaviors like smoking, go hand in hand with slower reactions.
So diseases do impact the neurology of our brain and body, leaving a mark in reaction times. Less clear however is how much reaction speed low skill is a risk factor. But some studies have even shown that it tends to correlate with a higher mortality ratio.
Types of tests
We said earlier that reaction speed is a narrow ability, and that is so because it is made up of several narrow abilities. One of them is simple reaction time, which is the speed at which someone is capable of reacting to the appearance of a stimuli. But there are other, and even more important ones, like complex reaction time, which is the speed at which the person is capable of detecting several stimuli and making a choice about them according to rules that have been previously decided.
Complex reaction time is an ability believed to represent better real life problems, so it should not be a surprise that it is more predictive of global intelligence than simple reaction times. Some studies have found complex reaction time to be 0.4 correlated with global IQ (which is pretty good), while simple reaction time is closer to 0.2. It seems however that this relationship is clearer for older people, while for younger people not so much.
Complex reaction time tests have many different forms and shapes, in comparison to the simple reaction tests which are basically just a simple stimulus shown on a screen. The basic forms of complex tests are recognition -when the person must react once it recognizes a stimulus-, discrimination -they must differentiate between them and act in some way- and selection -in which they must select those that fit some criteria-.
Another way of classifying the different types of test, as Khodadadi et al. (2014) explains in a review of the subject, is looking at the different senses that each test checks. While the most common is visual (waiting until you see the stimuli), others can be auditory. Interestingly, not each sense has the same behavior and evolution across age, etc...
Age, sex and other differences
Many studies have found a consistent and clear pattern of decline with age. The older someone is the worse, therefore longer reaction times. However, Dear & Deary (2017) have discovered that the pattern is different between simple reaction times, for which the top performance is achieved during adulthood and kept until 60 years of age, and complex reaction times, for which top performance progressively decreases as someone gets older.
In terms of sex differences, many studies have found women to perform worse. It was even considered rock-solid and a very well replicated finding. But recent studies, like the one of Woods et al. (2015) with top-notch technology have found that women actually perform equally and the differences could come simply from motor differences and habits.
Additionally, it is unclear the reason, but in many studies it is found that more education goes hand in hand with better reaction times. Some researchers think education creates some kind of better cognitive reserve that helps in many areas, including reaction time. Of course, people with more education will in general tend to be part of more supportive environments. One thing is for sure, to an important degree reaction speed is a genetically predisposed ability, but your environment, your upbringing, also matters a lot in determining how your brain evolves.
Reliability
Reaction speed tests are considered to be highly objective measurements that correlate reasonably well with global intelligence. However, we must be cautious. First, reliability between tests, that is how similar the results between tests of the same person are, is not very high. The reason is that many factors can seriously impact reaction speeds, like motivation, sleep, and others.
Second, they are objective but only very much so if all test takers use the same hardware, which only happens in the lab. In 2020, researchers of the “timing mega-study” found that some important factors causing the differences where the type of screen (how fast it refreshes, which is the Hz of the screen), the browser used, OS (Windows, Mac, …) or even the type of mouse, all of which can introduce considerably different lags. As a fun example, just know that using a gaming mouse reduces response times by around 6 or 7 milliseconds. Now I understand why gaming-powered kids always beat me at shooting videogames.
But that being said, it does not mean however that an online test is not valuable. In fact, the mega-study found that when those factors, like browser, OS, and others, are reasonably controlled or segmented for results, the results can be quite good. Nevertheless, as scores have a higher degree of error than in other types of tasks, any conclusion should be made more about the bigger picture than about any specific micro-measurement.
How to improve
As you might expect, such a low-level ability is not easily modifiable. Being highly associated with neurological functioning and health, it is unlikely to improve just with some common training.
If you just want to perform better on a specific day, we recommend doing everything that would help you be fresh. That is, sleep well, eat well, do sport and exercise, try to motivate yourself and meditate to grow a calm mind. All these, seemingly simple tasks, prepare you for success. Because as we said before, they are factors that cause a lot of change between one try and another.
In doing these tasks, you can also practice them, and sometimes that will slightly improve your scores. But know that in general, this does not reflect a true improvement of your ability. Just a learning effect. And in fact, many researchers use changing tasks and stimuli, or even random ones, to overcome this learning problem.
And yet even if there is no clear study showing how to reliably improve your reaction speed in the long run, from what has been discovered we can expect that keeping a healthy brain and body will always protect your ability, and even improve it. Take care of your body, exercise, eat well, do not undergo too much stress, and educate yourself by learning new things. If it does not improve it, at least doing this will help you maintain longer your neurological health and therefore reaction speed.
Even though it is an ability that does not impact very directly most of our daily activities, its impact seems to be important in an indirect way, enabling the brain to work. And even in some specific activities the impact is very direct. Think of situations that need immediate action, like driving, dangers, sports, etc…those will certainly benefit from a solid reaction speed.
Summarizing
Reaction speed tests, as we have seen, are one of the oldest psychological tests. They are an objective measurement but can lack precision if not done under very controlled circumstances. It is a great predictor of intelligence and health. But we would only interpret any of its results taking them as intervals with a certain degree of error. In any case, they are fun tests, and you can try a simple reaction time test now with us.
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