Cedric Chin

One of the most important jobs in the egg industry is the job of the sexer: a human being who can quickly and accurately tell if a given chick is male or female. The earlier this is done, the quicker a chick can be put on the ‘optimise-food-for-eggs’ path, and the less likely a farm has to spend costly feed for male chicks. 

Sexing is a lot tougher than it sounds, because chickens don’t have penises. 

Chicken sexers are therefore one of the most lucrative jobs you can have in the poultry industry. They are the difference between a backyard egg farm and an industrial concern. This Pacific Standard article , for instance, says that sexers are ‘guarded like state secrets and paid like local gentry’ — starting at $60,000 a year.

The interesting thing about this story is how chicken sexers are taught. Imagine that you’re a sexer trainee, and you’re put in a room with 10,000 chicks, served to you in trays of 100. You’re asked to pick them up one at a time and put them in a tray marked ‘male’ or ‘female’; how do you learn to do this? Most people start out horribly: they turn a chick upside down, squeeze its bottom and … they can’t tell. They don’t know where to start. 

The picture gets worse when you think about the end goal: a professional sexer can sort a thousand birds an hour with over 98% accuracy — one Hugh Grove from Oregon could hit 1500 an hour at his peak. How do you get from “it’s yellow and it doesn’t have a penis, what?” to an average of 0.5 seconds per chick?

If you think the answer is to sit a large group of people in a lecture theatre, maybe for a course titled “Chicken Sexing 101”, where an expert stands in front of an audience and describes just how to squeeze chicks — well, you’re wrong. Expert sexers can’t explain how they know. They just … do. And the people they train can’t explain it any better than they do.

The answer to this conundrum emerged in Japan in the 1920s. The Japanese figured out that expert chick sexers could pass on their expertise by giving trainees immediate feedback. They just had to do that for thousands of chicks, over a period of a few years. 

So, let’s imagine this: you’re a trainee sexer, you’re back in the room with 10,000 chicks. You grab one and … you guess — that is, you put it in a random tray, let's say the one marked FEMALE. 

The expert immediately says: “no”.

You correct your mistake, put the chick in the male tray, and move to the next chick. You get this one right, but it feels totally random. This goes on for a long time. 

A gajillion chicks later, you feel that something changes. You begin scoring better than random. Given enough time — courses at the Zen-Nippon Chick Sexing School are about two years long, so let’s say after two years of intensive sexing — you eventually hit 98% accuracy rates … and you still don’t know why. Your conscious mind thinks that it’s randomly selecting, but an invisible force guides your hand to the right tray. 

This learning technique is called perceptual exposure — and it’s part of the puzzle of how experts gain expertise.