Star Turn

十月 26, 2001

Students at Cardiff are annually shown that when it comes to concrete thought, they are bird brains. David Mosford meets the pigeon man who likes to strut his stuff

John Pearce is an experimental psychologist with a chair at Cardiff University but he is better known on campus as the pigeon man.

Pearce's introductory lecture to first-year students has made an impact for 12 years and has even been televised for the television show, Animal Minds.

Addressing a packed and noisy lecture theatre, Pearce is breezy when he apologises that yet again the audiovisual aids have broken down but he makes no apology for putting his students through the same experiment that he performed 12 years ago on pigeons.

"I'm going to show you a sequence of patterns. Your job is to try to predict which patterns will be followed by a musical tone. When I did this with pigeons, they had to peck the screen correctly to get seed. Obviously I can't give you food so I just want you to mark on the sheet provided what you predict and I want you to let me know when you think you know the answer."

Having studied at Leeds, Sussex, York and Cambridge universities, Pearce is an unashamed show-off who happily combines fun with erudition.

He knows in advance that the first-years will struggle to discern a conceptual connection between the various green bar diagrams that appear before them and the musical tone that follows some, but not all of them.

Is what triggers the tone an ascending order to the columns? Or descending? Is it symmetrical, asymmetrical? Or equal height perhaps?

After ten minutes of sighs and frustrated guffaws Pearce asks: "How many of you have got it?" When hardly anyone ventures to raise a hand he points out airily "I should say that pigeons find this not too difficult."

The purpose of Pearce's experiment is not to humiliate students, although he does take a delight in referring to the assembled student body as bird brains. "OK stop now," he says. "Shall I put you out of your misery?" The answer is simple and blindingly obvious to pigeons. If the average height of the columns is low, the pigeons get food and the first-years hear a tone. If it is high, then neither event happens.

Pigeons are capable of concrete thought, argues Pearce. They think in pictures. That is why pigeons are able not only to recognise a tree but also a photograph of a tree.

Human beings on the other hand have both abstract and concrete thought. Abstraction needs words and symbols to occur. Concepts such as sameness and difference, concepts such as symmetrical and descending are possible only for creatures blessed with the ability to think abstractly.

Year after year when human beings take the Pearce test, the obvious answer - "low" or "high" - eludes them because they are busy trying to make abstract connections between the green bar diagrams, which are inappropriate in this context.

"That was what led you away from the simple explanation," Pearce tells his chastened audience adding that what pigs can achieve in his experience solely with concrete thought is remarkable.

"One of the fundamental questions that psychologists keep coming back to is to what extent are animals capable of abstract thought. If I were to stick my neck out, my feeling is that humans have it and animals don't," he says.

Human beings also have vanity and Pearce happily rounds off this experiment with a video of himself presenting this experiment on television. "As you know, I'm an arrogant sort of chap," he says.

The lecture is a tour de force and Pearce leaves his students with an intriguing thought. "Pigeons undertaking a similar experiment where they get rewarded with food every time they see a picture of one of Picasso's paintings also peck the screen for Matisse - whose work is very like Picasso's - but never for a Monet."

Not many people know that, but after listening to Pearce, 100 Cardiff undergraduates have a better idea why.

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