Arrow Drop: Choice Reaction Time and Hick's Law
Why more choices mean slower answers, and how a falling-arrow test measures it.
Reacting to one signal is fast. Choosing the right response from several is slower. Arrow Drop measures that choosing, under time pressure.
How to play
Arrows fall from the top. Always answer the one closest to the bottom: press that arrow key (or W A S D), or click or tap the matching button. A right answer clears it. There are 10 levels, from 10 arrows up to 30, from 0.5× to 2.5× speed, arriving one by one, in streams, in groups and in crowds.
Where it comes from
In 1952, William Hick showed that choice reaction time grows as the number of possible choices grows, in a regular way. This became known as Hick's law, and it is still used in interface design: fewer options on screen usually mean faster decisions.
What the task uses
Choice reaction, plus selective attention: with several arrows on screen, you have to find the lowest one and ignore the rest. Higher levels add speed, so you also have to plan ahead.
What practice can change
Practice makes you faster and more accurate here, as you learn the key mapping and stop hesitating. It has not been shown to speed up reactions in other settings.
A worked example
When several arrows are falling, look only at the one closest to the bottom. Suppose it points left while the one above points down. Press left, and only then move your attention to the next lowest arrow. Thinking "lowest first, always" keeps you from answering an arrow higher up by mistake.
Common mistakes
Answering the arrow you noticed first, rather than the lowest one, is common in crowded waves. Moving your fingers off the arrow keys slows you down. And at higher speeds, trying to answer two arrows at once often leads to mistakes.
Questions people ask
What is Hick's law? The finding that choice reactions get slower as the number of possible choices grows.
Keyboard or touch? Use whatever is comfortable, but compare scores only with the same input.
Will this speed up my reactions in games? You will get faster at this task. Carry-over is not proven.
Tips
Rest your fingers on the four keys before you start. Not medical advice.
Sources
Not medical advice. Stop if you feel dizzy, nauseous or strained.