Implicit Learning

Chickens and Airplanes: Implicit Learning

It’s Easy: Don’t Fall Down

Take a moment to consider a physical skill that you’re good at. Snowboarding, perhaps. Or surfing, riding a bike or even slacklining.

Now, think about what you would say if you had to write down a step by step guide for how to perform that skill.

“How to ride a bike: Step one: Start pedaling. Step two: Don’t fall down.”

Most motor patterns are stored as unconscious subroutines, or implicit knowledge. We know how to do them, but we don’t quite know how we know.

I’ve been on snowboarding trips in which new people would be along riding for their first time. Naturally, they would ask for members of the group to teach them how to snowboard.

The standard practice is to explain the theory of how the board’s edges, sidecut and camber work and how that relates to turning and stopping. After that, one makes sure that the new rider knows how to fall without breaking a wrist or tailbone or getting a concussion and then sets them off on their merry way to spend the day falling down every few seconds.

Acquisition of the skill doesn’t involve much teaching. It’s more about doing. The brain will learn as long as one provides sufficient repetitions for it to develop the necessary predictive patterns based on proprioceptive stimuli.

The process for teaching someone how to slackline, surf or ride a bike is comparable. The instructor provides the basic theory, such as how to pop up on a board, place one’s feet, stand with balance and control the board. From there the trainee has to practice that in real time in order to learn what it feels like to do it wrong and, eventually, to do it right.

With enough reps, what began as shaky, toddler-like attempts at emulating what surfing should look like begets a “click” moment in which suddenly one knows what surfing feels like and for the first time the rider has control over the process of paddling, popping up and riding the board.

The Secret Lives of the Brain

In Incognito: The Secret Lives of the Brain, David Eagleman describes two examples of implicit knowledge in which people are capable of skills that they can’t actually explain:  (Note: TheIncognito link above is an affiliate link. If you prefer the non-affiliate link, click here.)”

“The best chicken sexers in the world hail from Japan. When chicken hatchlings are born, large commercial hatcheries usually set about dividing them into males and females, and the practice of distinguishing the two genders is known as chick sexing. Sexing is necessary because the two genders receive different feeding programs: one for the females, who will eventually produce eggs, and another for the males, who are typically destined to be disposed of because of their uselessness in the commerce of producing eggs; only a few males are kept and fattened for meat. So the job of the chick sexer is to pick up each hatchling and quickly determine its sex in order to choose the correct bin to put it in. The problem is that the task is famously difficult: male and female chicks look exactly alike.

Well, almost exactly. The Japanese invented a method of sexing chicks known as vent sexing, by which expert chicken sexers could rapidly ascertain the sex of one-day-old hatchlings. Beginning in the 1930s, poultry breeders from around the world traveled to the Zen-Nippon Chick Sexing School in Japan to learn the technique.

The mystery was that no one could explain exactly how it was done. It was somehow based on very subtle visual cues, but the professional sexers could not report what those cues were. Instead, they would look at the chick’s rear (where the vent is) and simply seem to know the correct bin to throw it in.

And this is how the professionals taught the student sexers. The master would stand over the apprentice and watch. The students would pick up a chick, examine its rear, and toss it into one bin or the other. The master would give feedback: yes or no. After weeks on end of this activity, the student’s brain was trained up to masterful—albeit unconscious—levels.

Meanwhile, a similar story was unfolding oceans away. During World War II, under constant threat of bombings, the British had a great need to distinguish incoming aircraft quickly and accurately. Which aircraft were British planes coming home and which were German planes coming to bomb? Several airplane enthusiasts had proved to be excellent “spotters,” so the military eagerly employed their services. These spotters were so valuable that the government quickly tried to enlist more spotters—but they turned out to be rare and difficult to find. The government therefore tasked the spotters with training others. It was a grim attempt. The spotters tried to explain their strategies but failed. No one got it, not even the spotters themselves. Like the chicken sexers, the spotters had little idea how they did what they did—they simply saw the right answer.

With a little ingenuity, the British finally figured out how to successfully train new spotters: by trial-and-error feedback. A novice would hazard a guess and the expert would say yes or no. Eventually the novices became, like their mentors, vessels of the mysterious, ineffable expertise.

There can be a large gap between knowledge and awareness. When we examine skills that are not amenable to introspection, the first surprise is that implicit memory is completely separable from explicit memory: you can damage one without hurting the other. Consider patients with anterograde amnesia, who cannot consciously recall new experiences in their lives. If you spend an afternoon trying to teach them the video game Tetris, they will tell you the next day that they have no recollection of the experience, that they have never seen this video game before, and, most likely, that they have no idea who you are, either. But if you look at their performance on the game the next day, you’ll find that they have improved exactly as much as nonamnesiacs. Implicitly their brains have learned the game—the knowledge is simply not accessible to their consciousness. (Interestingly, if you wake up an amnesic patient during the night after they’ve played Tetris, they’ll report that they were dreaming of colorful falling blocks, but they have no idea why.)

Of course, it’s not just sexers and spotters and amnesiacs who enjoy unconscious learning: essentially everything about your interaction with the world rests on this process. You may have a difficult time putting into words the characteristics of your father’s walk, or the shape of his nose, or the way he laughs—but when you see someone who walks, looks, or laughs like him, you know it immediately.”

Just Drive

The most important concept to extract from that excerpt is the simple “yes/no” nature of implicit learning. With minimal guidance and trial and error, people were able to learn seemingly unattainable skills.

Learning, as it turns out, really can be as simple as trying, getting it wrong, and trying again. You don’t need to take notes. Your brain is doing it for you. All you have to do is drive.

Think back to the example of the surfer or the snowboarder, bumbling along on their first day. Every rep, every attempt at popping up on the surfboard or carving down the hill on a snowboard provides an avalanche of novel proprioceptive data to the brain. Over time, the brain begins to sort this data out into auto-associative patterns as it learns to tell the difference between “yes” movements and “no” movements.

Perception: The Active Comparison of Sensory Inputs with Internal Predictions

If the body feels X, and you do Y, the result will be Z. Prediction. This is why there are ten times as many fibers going from the visual cortex to the visual thalamus (the pathway by which incoming visual data is directed to conscious awareness) than the other way around. The cognitive portion of the brain puts a substantial amount of effort into predicting what visual data will be coming in via the eyes. Only the information which conflicts with these predictions is fed forward into consciousness.

When this happens and the visual thalamus sends forward information that was not accurately predicted by the cortex, the cortex adjusts and adds this data to the predictive vocabulary so that it can make a more accurate prediction in the future. The rest of the sensorimotor system works similarly.

The yes movements induce forward motion, balance and control. The no movements create that awful feeling of the heel-side edge of a snowboard catching in the snow an instant before the back of one’s head slams into the ground, or the frustrating feeling of a board disappearing out from under one’s feet and getting swallowed and tumbled by a wave.

Soon, what began as spastic, awkward movements becomes smooth, controlled and efficient motion. Just the right amount of edge necessary to carve the board from one side before transitioning to the other. A quick pop-up onto the surfboard and a nice turn down the shoulder of the wave.

The cortex of the brain has learned a multitude of sensory inputs and ways of adjusting to and reacting to them appropriately. The predictions sent forth are increasingly accurate and conscious effort is decreasingly necessary for performance of the skill. What was once an overwhelmingly foreign and complex task becomes second-nature.

10,000 Hours of Yes/No

Consider the popular meme that expertise in a pursuit takes roughly 10,000 hours of practice. Imagine a surfer, going from day one in the water to ten thousand hours of paddling, popping up and riding later. He or she will have gone through an unimaginable number of tiny variances in sensory input, mistakes and corrections. Just about every possible yes/no situation will have been experienced and added to the predictive vocabulary. The surfer has become an expert.

The simplicity of yes/no implicit learning does not mean that outside input or a coach is unnecessary. Coaches provide valuable insight and shortcuts, saving the trainee thousands of erroneous repetitions, struggling along through countless “no’s” in order to begin finding what a “yes” feels like. Blind trial and error is likely to discourage or injure a trainee before he or she makes it far enough along in the process to happen upon correct movement skills.

In the case of the chicken sexers and plane spotters, the only input the coach could provide was yes or no. There were no other variables. This is why “expert” level proficiency at this task was attained in a matter of weeks.

Like This?

In a physical process, the yes or no is often provided by the environment and the proprioceptive inputs which one’s brain must learn are substantially more varied. It’s not necessary for a snowboarding instructor to tell you that you did it wrong because your face slamming into the snow tells you.

The practitioner, possibly with the guidance of a coach, provides the input (move like this) and the environment produces the yes/no output. Initially, it’s a matter of falling or not falling, or the presence or absence of pain in a movement. Sometimes, such as in entry-level Olympic weightlifting, the student may not even know or be able to see whether the movement is being performed perfectly, and the coach is again providing simple yes/no feedback with each rep.

To have an adept coach provide a cue such as “push your hips farther back, neutral spine, weight on your heels and let the weight load your hamstrings as it comes down and back” while learning a kettlebell swing can provide a much more rapid path to the “click” feeling of a yes repetition, when the trainee suddenly realizes, “Oh! That’s what it should feel like” than if they were to simply swing away and wait to hit upon something that felt right.


Learning a new skill takes persistence. You have to endure countless no repetitions in order to eventually figure out what it takes to produce a yes and a thousand no’s don’t necessarily get you any closer to a yes. Seeking guidance from a professional can fast-forward you through the trial and error process and enable you to produce and learn from yes reps much faster than if you were to go it alone.

The fun part of learning a physical skill like surfing, climbing or snowboarding or even working with kettlebells or Olympic lifting is that as long as you keep providing the inputs your brain is doing the learning for you. Every fall, mistake and small success is another lesson. All you really have to do is enjoy the process.


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