``In Germany there was once a cart horse named Hans, owned by
one Herr von Osten.  Hans had to back the cart he pulled in a
circular drive, and his skill at doing this, the story goes, so
impressed von Osten that he decided that horses in general and
Hans in particular must be smarter than generally supposed.
Von Osten began doing various things with Hans, teaching
him to respond to questions either by tapping with a hoof a
certain number of times or else by indicating one of a number
of blocks on which the alphabet had been written.

Hans was a good learner, and in time philosophers, linguists
and psychologists from all over came to test his acumen.  It
turned out that Hans could not answer questions if he could
not see the person asking him.  It turned out further that if the
questioner was in sight, Hans could always find out what the
questioner thought was the correct answer, no amtter how hard
the questioner worked at remaining still and impassive.  Hans
apparently read minute changes in breathing, angles of the
eyebrows, etc., with an accucary we have trouble imagining.

This led to von Osten's being denounced as a fraud, and
he seems to have died an unhappy man, not so much on his
own account as on that of the horse in whom he so deeply
believed.  And there has now come to be a technical term in
academic studies of animal psychology, the ``Clever Hans
fallacy.''  This is the fallacy of supposing that an animal ``really''
understands words or symbols when what the animal is doing
is ``merely'' reading body language.  In the literature, this
notion is used to discredit virtually anyone who disagrees with the
writer in question as either a fraud and a charlatan or else as
just plain credulous and stupid.  There is an unhealthy air of
triumph in the rhythms of the prose of the people who do this
discrediting, and I have found myself moved to wonder why,
if the trainers and thinkers who believe that Hans illustrates
something more important are so discountable, they must be
attacked so often.

I told a friend of mine, the poet Josephine Miles, the story
of Clever Hans.  She said, in response to finding out that
humans couldn't conceal from Hans what counted as the correct
answer, ``But isn't that interesting!''

...I saw many interesting things along the way.  A student
giving a paper on post-parturition behavior on cats would
inadvertantly attribute to the mother cat a mental state,
such as caring about her kittens.  The student would be corrected
and would learn in time to deliver solemnly quantified reports on
the amount of licking behavior, suckling behavior and so on that was
``exhibited'' by the queens.  I wondered about that word ``exhibited.''
Exhibited to whom?  The researchers?  The kittens?  I also wondered
about the intellectual and spiritual futures of students so carefully
instructed in the terrible grammar such ways of talking entailed...''

 Vicki Hearne, _Adam's Task_  p4, p7