The Frontal Cortex

Metacognition in the Rat

I’m a contributor to Very Short List: Science, the latest offshoot of the VSL brand. (David Dobbs is another contributor.) For those who don’t know, VSL is a very short email on something interesting sent daily to your inbox. We recently featured this paper in the Science channel:

We’ve always known that rats were capable of complex thought: They memorize mazes and form elaborate social hierarchies. Now we’re learning that they seem to think about thinking itself. Until recently, that crucial skill — called metacognition — was believed to be unique to humans.

Scientists at the University of Georgia tasked rats with identifying “short” and “long” noises. Rodents that answered correctly were given six food pellets; those that answered wrong got nothing. So far, so Pavlovian. But the rats were also given a third option: If they declined to take the test, they received three food pellets. Most of the rats refused to identify the noises that were hardest to classify — thus suggesting a surprisingly evolved sense of their own knowledge and abilities. It’s something to think about the next time you reach for the rat poison.

For more on metacognition, check out my recent articles on the tip-of-the-tongue state and the presidential race.

Comments

  1. #1 OneEyedMan
    November 20, 2008

    How do they know that the rats don’t just press the third button when then think the sound is of medium length?

  2. #2 Anibal
    November 20, 2008

    Allison L. Foote and Jonathon D. Crystal, principal authors of the study, said that classification of noises in the middle of the range is difficult, but they compared accuracy during the discrimination lenght and forced choice task, leading them to reject an alternative hipothesis to metacognition in rats.

    That is, in their words: “An important feature of the design of this study is that
    we evaluated accuracy on trials in which the rats were
    forced to take the test. Moreover, the rats initiated these
    forced tests in the same manner as they initiated choice
    tests (i.e., with a nose-poke response). These factors
    limit the ability of alternative hypotheses to explain our
    data. For example, the forced duration tests are unlikely
    to have been unexpected and thereby unlikely to have
    disrupted accuracy. If forced choices had been surprising,
    we would expect longer latencies to respond in
    forced tests relative to choice tests. However, there
    was no evidence for a difference in the latency to respond
    with either a nose-poke (t[2] = 1.1, p > 0.05;
    mean 6 SEM: 0.61 6 0.19 s and 0.80 6 0.12 s for choice
    and forced tests, respectively) or lever-press response
    (t[2] = 0.4, p > 0.05; mean 6 SEM: 2.70 6 0.47 s and
    2.65 6 0.28 s for choice and forced tests, respectively).
    Consequently, the accuracy difference on forced and
    choice tests was not likely to be due to performance disruption
    from unexpected forced tests.”

  3. #3 David
    November 20, 2008

    I’m going to sign up for VSL – thanks for the tip.
    How did the rats signify their refusal to take the test?

  4. #4 Ryan Morehead
    November 20, 2008

    David: The rat presses a third bar.

    Metacognition in rats is, from what I can tell, a very controversial topic. A guy who looks at metacognition in chimps recently gave a talk at my school and he was extremely critical of the work on rats. He said their results could be readily accounted for by instrumental conditioning.

    There’s also a recent paper in Nature that says the same thing: dx.doi.org/10.1038/nature07200

    I tend to agree.

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