What is it with Chick Sexing?

Come back with me for a moment to my old high school. It is 1977 and a group of us grade-10 boys is hanging around in the hallways after lunch, looking for something–anything–to take the piss out of. We pass the guidance councilor’s room, a dentist’s waiting room kind of space that mostly goes unused but whose door is always wide open. Some recently installed  new technology–a job search “computer”–pulls us in. Here’s how it works: there is a catalog of job names. You choose the job you would like to know more about and enter it into the machine; and then a few weeks later you return to the office to pick up your *computer printout* of the job info. We recognize it as a gimmick right away.  We patiently listen to the explanation and then flip through the catalog to find silly jobs we can use to try out this computer printout system. And there in the “C” section we find what we are looking for: CHICK SEXER. It’s a giggly treat of an item and with great delight we enter the request into the machine and laugh about it for the rest of the day. Weeks later the folded 2-sheet  ringed printout arrives with only two lines of text on the first page and nothing below the perforation: A chick sexer is someone who determines the sex of baby chicks. This is done by turning the birds over and examining their bottoms to see if they are male of female. And that’s it. No info on how to become one. No info on pay. Nothing on working conditions. Nothing on certification or the difficulty of learning the skill. No mention of the thousand-birds-an-hour speed that master chick sexers attain. And absolutely nothing on the Japanese domination of the profession. The whole incident was then added to the meaningless use of technology box in my long-term memory, in addition to the  juvenile prank box. And the term check sexer floated around as brain junk for the next three decades.

Then last year in the span of only a few months, I came across chick sexer again in print,  in not one, but two books: Moonwalking with Einstein and Incognito. Both books use it to illustrate the effects of intense, focused practice. OK, sure, but why not unicyclists, jugglers, violinists, or short order cooks? What is it with chick sexing, I wondered?  Why all the interest in this obscure profession?

As best as I can figure out, it seems that most academic interest goes back to Biederman & Shiffrar’s (1987) article on chick sexing, subtitled, A Case Study and Expert Systems Analysis of a Difficult Perceptual-Learning Task. They took two groups of subjects and gave one instruction and some training with images in determining from among the vast array of possible chick bottoms, which are male and which are female. There is apparently, outside of a few standard configurations, quite a bit of variation. A control group got no instruction or training. Both groups were then asked to sex a pile of chicks, and their performance was compared to experts. Well, the trained group got  a 72% accuracy rate, not bad but pretty far short of the 95% accuracy rate of professionals. The control group, however, was also surprising. They got a 62% accuracy rate–just by using intuition. The presence of a  “prominent bead” probably means a male, they reported.

After the Biederman and Schiffrar article appeared, academic interest seems to have veered in the direction of the difference between the trained and professional group and how pros are able–without always being able to articulate–how they can categorize the rarer types of chick bottoms. Cognitive researchers like Harnad (1996) and philosophers like Brandom (1998) seem to have taken taken interest in the phenomenon and chick sexers became standard go-to guys for cognitive psychologists interested in how people learn complex tasks. In 2002, Horsey published an article, The Art of Chick Sexing (linked to the Wikipedia page on chick sexing),with a clear emphasis on skills that “are hard-earned and not accessible to introspection” (pg. 107). In the case of both Mr. Eagleman in Incognito and Mr. Foer inMoonwalking, it seems to be Horsey’s article and  this “unconscious” acquisition, picked up through copious amounts of intense focused practice that is of greatest interest. Horsey says that we shouldn’t necessarily be so impressed by chick sexers and expert wine tasters, etc. Every one of us is constantly making categorizations like these in our daily lives. We do it so well we aren’t even aware of the complexity of our feats. An example of one such skill is reading. Like any skill, it started with instruction and selective attention to cues. Then came practice and lots of it, until we reached the point where it became an automatic process. Reading  is “not based on gestalt properties [but] on discrete cues” (pg. 114). In the case of chicken sexers, their remarkable ability can be explained through the same process, with the addition of time performance pressure, regular immediate feedback, the social pressure the instructional environment, and the rewards (financial and otherwise) of a very marketable skill in the future.

The Horsey article is short and makes for interesting reading. It suggests suggests that just about any advanced level skill is possible, given the right conditions and effort and time. For me, the  Biederman and Shiffrar article also was very encouraging in the way that it showed how learning can be seen in stages. Even total amateurs were not total beginners. And with  focused attention to cues and practice, anyone is capable of better performance. Expert level performance is not so easy to attain, but it is more a matter of hard work than talent or magic. That’s a message I want my learners to embrace. Julie Dirksen in her fantastic book Design for How People Learn, ends with a quotation by Kathy Sierra: “Kicking ass is more fun regardless of the task. It’s more fun to know more. It’s more fun to be able to do more. It’s more fun to be able to help others do more.” I think that if we approach learning as a continuum of increasing power and fun, all the hard work involved becomes more palatable, even if that involves looking at 1000 chicken butts an hour.

One detail that made the story of the chick sexers interesting to me was the fact that the Zen-Nippon Chick Sexing School  in Nagoya, Japan produced and still produces a ridiculous number of the world’s best chick sexers. Indeed the vent method of chick sexing was invented by two researchers in Nagoya. The pictures above show the original school and one of those researchers, Professor Masui. Here are some more pictures, all of which come from a film produced by the school in the 1930s and recently re-discovered by HIRUNAGI Kanjun of the Nagoya University Museum.

The school is still in operation and you can read a fairly recent piece done on it here. Aside from being interesting for cognitive scientists, chick sexers lived lives that allowed them to cross cultures at a time when it was not easy to do so. Many Japanese chick sexers, both men and women, went to the US, Canada, and Europe to work and live in the pre-WWII era. The stories of their lives make for fascinating reading. As chick sexers, they were a type of freelance worker and they traveled widely, taking their skills from farm to farm. A great collection of first person history can be found at this site. There are some remarkable stories here of some very remarkable people. I highly recommend a visit.


Biederman, I. & M. M. Shiffrar (1987) Sexing day-old chicks. Journal of Experimental Psychology: Learning, Memory, and Cognition, 13: 640–645.

Brandom, , R.B. (1998). Insights and blindspots of reliabilism. Monist 81: 371-392.

Harnad, S. (1996).  Experimental analysis of naming behavior cannot explain naming capacity. Journal of the Experimental Analysis of Behavior 65: 262-64.

Horsey, R. (2002). The art of chicken sexing. London:  University College London Working Papers in Linguistics.

Hirunagi, K (2006). Original film of “Chick Sexing”: On the development and practice of baby chick sexing method was found. Bullitin of the Nagoya University Museum No. 22, 65-72.








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