Simple vs Choice Reaction Time: What's the Difference?
Simple reaction time is how fast you respond when there is one possible signal and one possible response, like clicking the moment a screen turns green. Choice reaction time is how fast you respond when there are several possible signals, each with its own correct response, like pressing a different key for each color. Choice reactions are slower because your brain has to work out which response is right before you move, and Hick's law describes how that delay grows as the number of options goes up.
Simple reaction time
In a simple reaction task you know exactly what to do before anything happens. Only one thing can appear, and only one response is correct. Your brain can prepare the movement in advance and just wait for the go signal.
For a healthy adult, simple visual reaction time is about 200-250ms, based on large studies such as the Baltimore Longitudinal Study of Aging. Online tests often read a little higher because screens and input devices add delay. Our simple reaction test measures this.
Choice reaction time
In a choice reaction task, more than one thing can happen. A red square means one key and a blue circle means another. Now your brain has two jobs: work out which signal appeared, then pick the matching response. Only then can you move.
That extra step costs time. The choice reaction test on this site uses four options, and most adults land around 300-350ms, roughly 100ms slower than their simple score.
You can see the same gap in real data. In a 2023 study of professional Counter-Strike players, the pros averaged 219ms on a simple mouse test and 332ms on a choice test. Inexperienced players averaged 271ms and 396ms. Experienced or not, the choice task added more than 100ms.
Simple vs choice reaction time at a glance
| Simple reaction time | Choice reaction time | Go/no-go | |
|---|---|---|---|
| Possible signals | One | Two or more | Two (go and no-go) |
| Possible responses | One | One per signal | One, or hold back |
| What your brain does | Detect the signal | Identify it, then pick a response | Identify it, then respond or stop |
| Typical adult time | 200-250ms | 300-350ms with four options | 280-320ms |
| Effect of more options | None | Slower, following Hick's law | Not applicable |
| Try it | Simple test | Choice test | Go/no-go test |
Where the idea came from
The Dutch scientist F.C. Donders first measured the difference in 1868. He compared three kinds of task: one signal and one response (simple), several signals with a response for each (choice), and several signals where you respond to only one (now called go/no-go). According to Kosinski's review of reaction time research, Donders showed that simple reactions were fastest and choice reactions slowest.
His idea was that subtracting one task's time from another's would show how long a single mental step takes. The go/no-go test is the middle task: you still have to identify the signal, but there is only one response, so you don't have to choose between several.
Hick's law: why more options means slower reactions
In 1952 the British psychologist W.E. Hick tested how reaction time changes as the number of options grows. He used 10 lamps arranged in a circle, with a key under each of his 10 fingers, and timed himself with different numbers of possible lamps. Reaction time rose with the logarithm of the number of choices.
In plain terms, each doubling of the options adds about the same amount of time. Going from 2 choices to 4 costs roughly as much as going from 4 to 8. So the first few extra options hurt the most, and later ones add less.
Hick's law is usually written today as:
Reaction time = a + b × log₂(n)
Here n is the number of equally likely options, a is the base time it takes to respond at all, and b is how much time each doubling of options adds. A 2018 review by Proctor and Schneider in the Quarterly Journal of Experimental Psychology notes that the slope b can range from zero to several hundred milliseconds, depending on the task and how much practice people have had.
When Hick's law bends
Proctor and Schneider describe two things that shrink the cost of extra choices.
Practice. In a 1968 study by Hale, people with eight choices were close to 500ms slower than people with two choices in the first session. By the fifth session, the gap was a little over 300ms. In a 2016 study, the gap between eight and two choices was down to 149ms after nearly 4,000 practice trials. It never disappeared.
Natural matches between signal and response. When the right response is obvious from the signal itself, extra options cost little or nothing. In a 1959 study, people responded to a vibration under one of their fingers by pressing with that finger, and their reaction time was the same with two, four, or eight options. Moving your eyes toward a light that appears also shows no slowdown as options increase.
Why the difference matters
Most real situations are choice reactions. A driver deciding whether to brake or swerve, a goalkeeper reading a penalty, a gamer picking which way to flick: each one has to identify the situation and choose a response. A simple reaction test gives you your raw speed. A choice reaction test is closer to what everyday decisions ask of you.
The two also change differently with age. Kosinski's review notes that reaction time slows with age and that the slowing is more marked for complex tasks than for simple ones.
For your own numbers, take the simple test and the choice test back to back. The difference between your two medians is roughly how long your brain spends choosing.
Frequently asked questions
What is the difference between simple and choice reaction time?
Simple reaction time has one signal and one response, so you only need to detect the signal. Choice reaction time has several signals, each with its own response, so you have to identify the signal and pick the matching response first. That makes choice reactions slower, typically by about 100ms.
What is a good choice reaction time?
On a four-option test, most adults score around 300-350ms, and under about 320ms is a good result. It depends on the number of options and how familiar the task is, so compare yourself on the same test over time.
What is Hick's law?
Hick's law says reaction time rises with the logarithm of the number of equally likely choices. Each doubling of the options adds roughly the same amount of time. W.E. Hick published it in 1952, and it is still used in research and interface design.
Why is choice reaction time slower than simple reaction time?
In a simple task your brain can prepare the movement before the signal arrives. In a choice task it can't, because it doesn't know which response it will need. It has to identify the signal and select a response first, and that extra processing takes time.
Is go/no-go a choice reaction test?
Not quite. In a go/no-go test you still have to identify the signal, but there is only one response: act or hold back. It sits between simple and choice reaction time, which is how Donders used it in 1868.