July 2, 2007
Posted by Jay Livingston
A link on some political blog – I wish I could recall whose – took me to this posting on a site called
StraightDope:
I recently read Phantoms by Dean Koontz and was curious about his description of the “flatworms in a maze” phenomenon – namely that a flatworm can be taught to negotiate a maze and then ground up and fed to a flatworm that has never seen the maze. This new flatworm will absorb the knowledge of the maze from the first flatworm.
I’ve never read Dean Koontz, but I’m pretty sure the cannibalized-learning theory is bunk, at least where it concerns flatworms. But the mention of these studies took me back to a summer long ago when I worked in a university psych lab run by two psychology professors. It was the beginning of my disillusionment with psychology. It was as though I’d taken a lowly summer job at a law firm and discovered that most lawyers never saw the inside of a courtroom and that their work did not in the least resemble that of Perry Mason.
I had just finished my first year of college, and at the time I still thought that psychologists studied ways to understand and heal minds that were troubled and confused. Minds like my own. I also thought that a professor’s work involved the teaching of students – courses, lectures, exams, that sort of thing. But these two men did neither. They were researchers, and most of their research was about communication in rhesus monkeys. The way they treated the monkeys would today probably land these guys in jail, but as I said, this was a long time ago.
Their domain was the top two floors of one of those tall buildings that gets very narrow at the top. There were a half-dozen linoleum-floored rooms, most of them occupied by monkeys. Most of the monkeys were in cages. The few in the experiment were kept in uncomfortable “primate chairs” that allowed very little movement. Our own little Gitmo.
That summer the professors had read a journal article showing that planaria (flatworms) could be conditioned to swim or crawl a maze. For some reason, the article inspired them to branch out from monkeys and to try to replicate these experiments. Step one was to buy some flatworms – I guess there must have been a planaria supply house. Step two was to assign the groundwork to me.
Planaria (flatworms) are very simple organisms. They are worms, and they are flat. They measure
less than a half-inch, with a triangular head featuring two eyes that are set so close together it makes them look cross-eyed.
My job included their care, feeding, and education (or “conditioning” as psychologists call it). Feeding meant dropping a piece of raw beef liver into each worm’s Petri dish. The hungry worm would crawl up on the liver and chow down. For their conditioning, I was to put the flatworm in a narrow, water-filled trough with electrodes at each end. I would then turn on a light — planaria are senstive to light — give the worm a second to realize that the light was on, and then zap him. The worm’s body would contract.
It was “classical conditioning.” The idea was that the worms would learn the light-shock connection. Then, even without the jolt of electricity, the worm would react to the light the same way it reacted to the shock, just as Pavlov’s dogs started salivating at the mere sound of a bell because it had been rung so often at Alpo time.
It sounds easy, but there was one catch. How do you move a worm from its Petri dish to the experimental trough? Our technique was to dip an eyedropper into the dish, suck the worm into the eyedropper, then squirt him out into the trough. After the worm’s experimental session (I forget how many light-shock trials I hit them with each time, maybe twenty), I would put the worm back using the same suck-and-squirt method. Unfortunately, the eyedropper aperture was a bit narrow, and the worm got squeezed each time in its rough passage in or out of the dropper.
The research plan was that after we succeeded with the classical conditioning, we would move on to the “operant conditioning” phase, teaching the little guys to swim a maze – i.e., to bear
right at a Y-intersection.
We never got that far. The hardest part turned out to be keeping the planaria alive. Each morning I would check the tank and find a few more of my charges getting paler and paler, becoming translucent and finally giving up the ghost. We brought in new subjects, but they too withered. I figured that the reason for their failure to thrive was the combination of being squeezed through the narrow aperture of the eyedropper and then being electrocuted. That and maybe having to live in water that quickly became murky from the liver decomposing in it.
When I left at the end of the summer, I had not taught a single worm anything – preparation for my eventual career – and as far as I know, my bosses gave up without a publication. Ever since, I have been extremely skeptical about reported findings on flatworm learning. Yes, I know that these studies have been done and replicated. I just choose not to believe them until I see them first hand.
My bosses did publish several articles about the monkeys, but my first-hand experience with those experiments makes me very skeptical of those results too. But that’s another story.
The road sign, which I found using Google, is from the MySpace page ofTeresasaurus Rex .
