flatworms and contagious ignorance

The flatworm report is a nice example of how the fascinating but unfortunately false factoid can travel much further than the straight dope.

That flatworms are proof of edible memory is one of the things that I “knew” until I was enlightened–I first got it out of a throwaway line in Joe Haldeman’s Forever War, and had it confirmed a couple of times by other sources–Koontz’s Phantoms being one of them.

OOPS–forgot the link. The original staff report is

http://www.straightdope.com/mailbag/mflatworm.html

Like electricity, people tend seek the path of least resistance. So it’s easier if you’re just told a factiod that sounds like it can be believed or because it fits in with a “pre-installed” belief structure than to actually go and look it up. Although, it never seemed muck like “work” to me nor terribly resistive (hard). It would seem that Cecil and his able co-conspirators have job security in the Straight Dope, eh?

The “Straight Dope” report is, I am sorry to say, flat-out wrong. The classic worm-runner experiments did not involve food, but rather worms that had been trained to associate light with electric shocks.

The exact interpretation of these experiments is still debated, and the early conclusion that a transfer of memory per se was involved has been pretty much dismissed, but I cannot find any source for the belief that the research itself have been dismissed as mere experimental error. See http://216.239.51.100/search?q=cache:jEmfDxEDBC8C:www.utsc.utoronto.ca/~milgram/nroc61/learn2.doc+%2Brna+%2Bmemory+%2Bflatworm+%2Bshock+%2Blight+%2Bmcconnell&hl=en&ie=UTF-8, for example.

Good, because I was hoping to chow down on Cecil’s brain when he’s done with it.

I’ll second that, and also provide the citation for the original study:

Thompson, R., & McConnell, J. V. (1955). Classical conditioning in the planarian, Dugesia dorotocephala. Journal of Comparative and Physiological Psychology, 48, 65-68.

Here’s another widely-cited source:

McConnell, J. V. (1964). Cannibalism and memory in flatworms. New Scientist, 21, 465-468.

I hasten to add that the Straight Dope Staff Report also says that the classic worm-runner experiment did not involve food, and that it involved worms that had been trained by electric shocks.

(However, it claims that the electric shocks were used to convince the flatworms to take one particular path in a y-shaped branching corridor, and makes no mention of associating light with them.)

The first time I heard mention of the study is was followed by the “announcement” that a couple of scientists wanted to eat Einstein’s brain. A quick google search didn’t turn anything up.

Sorry, John, I don’t understand your comment. The question was about food, answered in the first paragraph of the report. The second paragraph of the Staff Report deals with the electric shocks. Why do you say the Staff Report is wrong?

When I checked out the Report again, there was a second paragraph I don’t remember being there the first time I read it. Did this happen to anyone else? It could explain John’s comment.

He seemed pretty clear to me. The staff report says, “the original experiments on flatworm learning… did not involve a maze, but rather a Y-shaped trough: when a flatworm reached the fork, the experimenters gave it a shock to induce it to turn to the right-hand fork. They kept track of how long it took the worm to learn to go right every time.” However, the original experiments simply involved exposing the worms to light and giving them an electric shock. (The shock caused the worms to contract.) The idea was to see if they could classically condition (a la Pavlov’s dog) the worms to contract upon exposure to light. The experimenters then chopped up the conditioned worms and fed them to non-conditioned worms to see if the memory had been preserved. There was no Y-shaped trough, no food, and no turning left or right.

I don’t remember seeing that second paragraph either…?

You are correct. At the time that John W. Kennedy posted his comment, the second paragraph of the article in question was not posted on line. Only the first paragraph was present at that time, explaining the discrepancy between his comment and the subsequent ones.

Ah, thanks, Colibri. What I get for taking some days off.

OK, with the second paragraph now there, the question comes up: what’s being transferred? Is it the specific knowledge to go right, or is it general learning capability? In other words, consider the following experiment: I train one flatworm to always turn right. I then feed it to a second flatworm, and try to train it to always go left. Will the second flatworm learn more or less quickly?

Staffer Doug’s pathetic excuse of a report is particularly annoying because the subject matter, although perilously close to pseudo-science, is a fascinating example of Science trying to deal with it’s own inner demons and foibles. There is quite a story here and it should be examined, not dismissed with pat skepticism and invented particulars.

My source for the following summary is a book by Jay Ingram called “The Barmaids Brain” - a look at the edges of science and some of it’s controversies and unsolved mysteries. Ingram is known in Canada as a scientific popularizer and host of radio and television science shows. I would assess him as professional and a healthy skeptic.

In the 1950’s American psychologist James McConnell and his colleague Robert Thompson worked with conditioned response in planaria - a common type of flatworm. They set up an experiment where planaria were put in a plastic trough with water in the bottom and electrodes at each end. Mounted above the trough were light bulbs. The idea was that the lights would be made to flash on just before the worms were given a jolt with the electrodes. The worms appeared to react to this torment by turning their heads and contracting their bodies. Eventually they become conditioned and would exhibit the “scrunching” in response to the light alone.

McConnell published these experiments in 1955, demonstrating that planaria could be conditioned in the classical sense. He then set upon a series of experiments and sensational findings…

First he claimed that the worms ability to regenerate itself when sliced in two included the conditioned learning. This happened in both the head end and the tail end of the worm!

Next he tried, unsuccessfully, to graft parts of a trained worm onto an untrained one. A variation in this was ultimately pulled off: he found conditions where he could get an untrained worm to eat a trained worm. He observed that the cannibal worms performed significantly better in the light conditioning than a control set of worms.

“McConnell admitted in one of the first publications of this data that ‘we are most definitely out on a limb of some kind,’ although it’s unlikely he knew just how far.”

There was harsh reaction to his reports: it seemed that some scientist simply couldn’t accept McConnell’s work because they couldn’t envision how it could be true – they couldn’t see any mechanism that could account for the ingested learning. At that time, there were already strong opinions on how learning involved a “re-wiring” of the brain. To suggest that it could take molecular or chemical form was dismissed out of hand.

There were formal objections too. These types of experiments involve subjective assessments on the part of the observer, for example, did that worm “scrunch” or did it not? As well, experience with the worms and recognizing when and how they learned might be a big factor in getting positive results.

  • “… in the court of science evidence is primary, and that means replication. Controversial experiments should be repeated in an open-minded way by other scientists in other labs. Either the results hold or they don’t – at least that’s the way it’s supposed to go. But it’s rarely the case that a scientist will repeat another’s work to the letter, and as soon as the experimental details differ, uncertainty and controversy walk in. That uncertainty characterized the scientific follow-up to McConnell’s work is a deep understatement”*

Through the 1960’s some experiments supported McConnell and some did not. A particularly damning blow came in 1966 when a letter submitted to the journal Science signed by 23 researchers affiliated with 7 institutions refuted chemical transfers of memory in rats. Oddly enough, this letter ends with a mixed message:* “We feel it would be unfortunate if these negative findings were to be taken as a signal for abandoning the pursuit of a result of enormous potential significance… Failure to reproduce results is not, after all, unusual in the early phase of research when all relevant variables are as yet unspecified.”

“The bottom line is that by the very early 1970’s the planaria work had been abandoned, even though some researchers who lumped all the experiments together and analyzed them came up with more positive results than negative.”*

McConnell himself added to controversy.* “He was unusual, iconoclastic and very public, none of which stood him in good stead… was also a tireless public communicator, a role that scientific colleagues often resent”*. McConnell talked to the press about “memory pills” – this didn’t help his credibility with fellow Psychologists. His assertions that technology could play a role in behaviour modification drew interest from another weird character:

  • “In a final, bizarre twist to the story, McConnell was the target of an assassination attempt by the Unabomber on November 15, 1985. McConnell wasn’t gravely injured by the letter bomb, but his hearing was permanently impaired.”

“James McConnell died in 1990. To my knowledge no one trains planaria to do memory transfer experiments any more. Some of the people left the field not so much because they didn’t believe in it, but because their peers were suspicious of it…”

“But when you look back over the entire saga, it seems memory transfer was not so much disproven as abandoned. In the words of sociologists Harry Collins and Trevor Pinch, ‘We no longer believe in memory transfer but this is because we tired of it, because more interesting problems came along, and because the principal investigators lost their credibility. Memory transfer was never quite disproved; it just ceased to occupy the scientific imagination.’” *

I’m surprised no one has mentioned that Larry Niven used this in a number of stories. See his A Wprld out of Time and the short story it was based on.

IIRC, Martin Gardner wrote about this, too.

K364 wrote:

“Staffer Doug’s pathetic excuse of a report is particularly annoying because the subject matter, although perilously close to pseudo-science, is a fascinating example of Science trying to deal with it’s own inner demons and foibles. There is quite a story here and it should be examined, not dismissed with pat skepticism and invented particulars.”

I think that’s just a wee bit harsh. It’s certainly not pat skepticism, since I point out that there is definitely some change induced. As for invented particulars, that’s what one gets when one reads a skimpy summary. To wit:

“They set up an experiment where planaria were put in a plastic trough with water in the bottom and electrodes at each end. Mounted above the trough were light bulbs. The idea was that the lights would be made to flash on just before the worms were given a jolt with the electrodes. The worms appeared to react to this torment by turning their heads and contracting their bodies.”

The summary of this experiment that I found stated “Flatworms were placed in a trough and stimulated to turn their heads in response to an electric shock”. Given that the classroom kits intended to replicate this experiment come with Y-shaped troughs, and making the flatworms choose by turning, I think it is forgiveable that I concluded that the two things were similar.

Aha! Another altered document in the John Kennedy conspiracy!

<ducking and running>