Let’s kick off this article with a true story from the US. Back in 1844, 32 years before Alexander Graham Bell invented the telephone, the world still relied on letters sent by train and horse-drawn carriages to share news.
Samuel Morse, an inventor, created America’s first telegraph system. He set up a line running along the railroad between Baltimore and Washington, DC, over 60 km long. Morse decided to test his invention during the Democratic National Convention.
The convention was held in Baltimore, and Morse personally manned the Washington end of the line when he received an urgent telegram. It said the delegates had agreed to nominate Senator Silas Wright for Vice President. Now, they wanted to know if Wright, who was in Washington, agreed.
Wright asked Morse to tap a single word “No” back on the telegraph. Thanks to Morse code reaching speeds of 16.5 words per minute and electrical signals traveling at about three-quarters the speed of light, the message reached Baltimore within seconds.
The incredible speed shocked the convention chair. He sent a delegation by train to Washington to confirm the answer. Hours later, they returned with the same reply.
From then on, telegraphy was used for direct communication between Baltimore and Washington, DC. Soon, it revolutionized how the world received news.
***
Almost 80 years after Morse’s invention, Taiwan now boasts the world’s fastest internet, transmitting 42.5 million words per second (85.02 Mbps), with ping times from your home modem to servers measured in fractions of a second.
But this also reveals a truth: no matter how fast signals travel, once they cross space, delay happens.
Even light takes over 8 minutes to travel from the Sun to Earth. Your thoughts right now aren’t exempt from this rule, they have speed and lag too!
Ever wondered how fast those numbers really are? How quickly can humans think? And do we ever experience lag?
We often assume humans react instantly and thoughts flash in the brain without delay. But try this experiment: touch a flame and you’ll pull your hand back before you even feel the burn.
What’s going on? You’d expect to feel pain first, then pull away. Actually, the reflex to pull back and the sensation of pain travel along two different nerve pathways of different lengths. This difference causes the delay and proves thoughts travel at a limited speed.
Let’s talk about reflexes first. Reflexes are automatic, quick responses to stimuli that help protect the body from danger. They’re evolution’s built-in survival code.
Imagine a gazelle’s fate if it didn’t run the moment it spotted a lion. Your hand would get burned if you didn’t pull away from fire, and without quick reactions to avoid a speeding car, you could lose your life.
Interestingly, scientists found reflex nerve signals don’t even need to go through your brain. They start at sensory nerve endings, pass through spinal cord interneurons, then switch to motor neurons in muscles.
For example, with the burn reflex:
The pain sensation arrives after you’ve pulled your hand back because it travels a longer path from your arm to the brain, plus the brain needs time to process the signals, which we’ll discuss later.
But the speed of nerve impulses along both paths is similar since they’re electrical signals jumping neuron to neuron. Neurons connect via axons and dendrites, forming nerve pathways like Morse’s telegraph lines.
You can calculate nerve transmission speed with the formula v = d / t (speed equals distance divided by time). The round trip from fingertip to spinal cord and back to arm muscles is about 1 meter. Reflex time to fire is 15-30 milliseconds.
So nerve signals travel roughly 33-66 meters per second, or 120-240 km/h.
Lab experiments confirm average nerve impulse speed between neurons is about 180 km/h. That’s roughly the average speed of a thought.
But average means some people think slower, like the elderly with aging nerve pathways, while others think faster with wider nerve bandwidth.
Researchers show people with thicker axons transmit signals faster because electrical resistance drops as wire thickness increases.
Those with thicker myelin sheaths, the fatty coating around axons, reduce signal loss further, speeding reflexes and thoughts even more.
Some nerve impulses can reach speeds up to 432 km/h. Think of Bruce Lee’s punches or sprinters crouching at the starting line waiting for the gun.
So now you know your thoughts can sometimes race faster than a Lamborghini Aventador, but that doesn’t mean we escape lag. Even the fastest sprinter takes about 150 milliseconds to start moving after hearing the gun, and most of us take around 200 milliseconds.
You might think you jump instantly, but 200 milliseconds is enough time for nerve signals to circle your brain and muscles over 10 times. Ideally, you’d react in 20 milliseconds, but somewhere the signal gets held up.
Science calls this delay “reaction time“, the lag between stimulus and your response. To understand reaction time, nothing beats the classic trick of dropping a bill:
The game is simple: I hold this bill between your fingers. When I drop it, if you catch it, it’s yours. If not, you lose nothing. Sounds easy, right? Trust me, you won’t win.
Try it with someone before we dive back into the numbers.
Unlike the automatic burn reflex, your visual reaction to the bill or a sprinter’s auditory reaction to the starting gun are conditioned responses.
We learn these reflexes, so their nerve signals must travel back to the brain for processing before triggering movement, not straight through spinal reflex pathways.
For vision, light waves from the bill hit photoreceptors in your retina, converting light to electrical signals sent to your visual cortex.
The starting gun’s sound waves vibrate your eardrum, converted to nerve signals in your inner ear, then sent to your auditory cortex.
Processing in these brain areas takes time and causes delay. But this delay helps your brain build an internal picture of the outside world, understanding what you face.
Sometimes this processing is complex and slow, like when viewing art in a gallery. Everyone interprets the painting differently based on their brain’s signal processing.
But for simple signals like the bill or starting gun, we all know what to do. After processing, the brain sends signals down motor nerves to your fingers or legs, triggering the catch or sprint.
The catch is, brain processing time never dips below 150 milliseconds for elite sprinters and averages 200 milliseconds for most people. Don’t believe me? Test your reaction time here.
Back to the bill: in 200 milliseconds, gravity pulls it down about 19.6 cm, enough to slip through your fingers. So unless you find a bill longer than 20 cm, you won’t win. The Vietnamese 500,000 dong note is only 14 cm.
Check out this smashed old van, one of the most shared photos online last week. The female driver was learning with her instructor, and luckily both only suffered minor injuries after crashing into a sand truck.
Their awkward situation quickly became a meme, sparking debates about women drivers, strict instructors, and how driving lessons end.
Here’s a fact: studies show women’s brake reaction times are slower than men’s.
The difference is small, about 30 milliseconds. But at 60 km/h, a female driver braking immediately still travels 0.5 meters farther than a male driver. Sometimes that half meter can be the difference between life and death.
Countless studies link reaction time to car accident risk. Up to 57% of crashes are caused solely by driver error. Combined with external factors, human error accounts for 90% of accidents.
Theoretically, ideal driver reaction time is 0.2 seconds. But real tests show it’s often much longer, ranging from 0.78 to 2.5 seconds.
Many factors can slow reaction time: fatigue, sleepiness, alcohol, stress, and even a driving instructor lecturing you nonstop.
That’s right, it’s tough to react and think at the same time. Thinking can distract you, increasing reaction time and raising accident risk.
Yogi Berra, the legendary American baseball player, once shouted at his coach during a swing: “How can you think and hit at the same time?”
Context: a baseball pitch averages 120 km/h and can reach nearly 170 km/h.
A penalty kick in soccer can reach 128 km/h. Do the math and you’ll see why the 11-meter spot is more luck than skill.
At 112 km/h average, a penalty ball crosses the goal line in about 350 milliseconds. The fastest goalkeeper needs 150 milliseconds to spot the ball’s direction, and by then the ball is just over 6 meters away.
Diving takes another 350-550 milliseconds. So if the shot is accurate, the ball’s already in the net. That’s why most goalkeepers dive early, turning the penalty into a gamble rather than a sure loss.
Understanding reflexes, thought speed, and brain delay isn’t just trivia, it’s vital for life. Be grateful for your automatic reflexes protecting you and aware of brain lag to stay safe in emergencies.
Try testing your reaction time here: https://humanbenchmark.com/tests/reactiontime. See if your thinking speed beats the average!
