Brown, Andrew, New Statesman (1996)
Andrew Brown on the mysteries of chicken sexing
Enough chicken sexing already. The whole point of chicken sexing is that no one knows how to do it: even the trained chicken sexers, though they often get it right, can't explain how they manage it. So their performance is extremely interesting to anyone who cares about how humans actually think, which includes all serious artificial intelligence researchers; and many of them hang out on a wonderful set of mailing lists called "psyche-L", "psyche-b" and similar names. These are almost the last places I know of on the Internet that still feel as the whole thing did ten years ago, as if it were the largest university bar in the world: the bar of educated world opinion. Students and grand professors mingle wildly.
A couple of months ago there was a flare-up of interest in chicken sexing there which showed these lists at their best. A researcher in Los Angeles started it by asking whether it was true that chicken sexers did it without consciousness. Someone in Sheffield replied with a reference to a paper in the Journal of Experimental Psychology called "Sexing day-old chicks - a case-study and expert systems-analysis of a difficult perceptual-learning task". This is apparently related to other tasks which we can learn to do without ever explaining how, such as discriminating between different vintages of wine; sadly no one provided references to papers on the perceptual mechanisms involved in wine-tasting.
At this point, Joe Jeffrey, a professor of computer science, objected that skills of this sort are not at all uncommon. In fact, "this is simply another example of a very common fact: a person's ability to do things far exceeds his/her ability to describe what he/she does. I don't know why one would invent a term such as 'implicit cognition' for the phenomenon, implying by contrast that more 'ordinary' or 'non-implicit' cognition involves the ability to describe what one does or sees."
So far this might be any discussion of perception and artificial intelligence; what I loved was what happened next: Stan Klein, a Berkeley psychologist, announced that he had grown up on a chicken farm, and thus knew more than anyone else about the subject. The point, he said, was that chicken sexers clearly had specialised knowledge inaccessible to other people: when his parents bought a batch of 500 chicks as egg layers, only three or four would turn out to be cockerels. "Now for the other part of my expertise," Klein went on, "my psychophysics hat. …