30 July 2007

Angst vor Ratten?

Ich nicht. Ich mag sie sogar. Anders als Mäuse, diese kleinen Hektiker, sind Ratten die meiste Zeit ziemlich entspannt und geduldig. Was nicht heißen soll, dass ich gerne wilde Ratten in der Wohnung hätte, da freilebende Ratten alle möglichen Krankheiten übertragen können, aber das trifft auf andere wildlebende Tiere auch zu - die kommen nur in der Regel nicht in so engen Kontakt mit Menschen.

'Smart, Curious, Ticklish. Rats?' heißt ein Artikel in der New York Times, der die bekannten und weniger bekannten Fakten zu Ratten zusammenfasst. Da sind ein paar Dinge dabei, die ich auch nicht wusste - Ratten sind kitzelig? Muss ich mal ausprobieren.

They’re surprisingly self-aware. They laugh when tickled, especially when they’re young, and they have ticklish spots; tickle the nape of a rat pup’s neck and it will squeal ultrasonically in a soundgram pattern like that of a human giggle. Rats dream as we dream, in epic narratives of navigation and thwarted efforts at escape: When scientists at the Massachusetts Institute of Technology tracked the neuronal activity of rats in REM sleep, the researchers saw the same firing patterns they had seen in wakeful rats wending their way through those notorious rat mazes.

Rats can learn to crave the same drugs that we do — alcohol, cocaine, nicotine, amphetamine — and they, like us, will sometimes indulge themselves to death. They’re sociable, curious and love to be touched — nicely, that is. If a rat has been trained to associate a certain sound with a mild shock to its tail, and the bell tolls but the shock doesn’t come, the rat will inhale deeply with what can only be called a sigh of relief.


Rats have personalities, and they can be glum or cheerful depending on their upbringing and circumstances. One study showed that rats accustomed to good times tend to be optimists, while those reared in unstable conditions become pessimists. Both rats will learn to associate one sound with a good event — a gift of food — and another sound with no food, but when exposed to an ambiguous sound, the optimist will run over expecting to be fed and the pessimist will grumble and skulk away, expecting nothing.

In another recent study, Jonathon D. Crystal, a psychologist at the University of Georgia in Athens, and his colleague Allison Foote were astonished to discover that rats display evidence of metacognition: they know what they know and what they don’t know. Metacognition, a talent previously detected only in primates, is best exemplified by the experience of students scanning the questions on a final exam and having a pretty good sense of what their grade is likely to be. In the Georgia study, rats were asked to show their ability to distinguish between tones lasting about 2 seconds, and sounds of about 8 seconds, by pressing one or another lever. If the rat guessed correctly, it was rewarded with a large meal; if it judged incorrectly, it got nothing.

For each trial, the rat could, after hearing the tone, opt to either take the test and press the short or long lever, or poke its nose through a side of the chamber designated the, “I don’t know” option, at which point it would get a tiny snack. During the trials, the rats made clear they knew their audio limits. The closer the tones were to either 2 or 8 seconds, the likelier the rats were to express confidence in their judgment by indicating they wanted to take the lever test and earn their full-course dinner. But as the tones edged into the ambiguous realms of 4 seconds, the rats began opting ever more often for modest but reliable morsels of the clueless option.

Rats do not lie, and, when the stakes are this high, neither do they gamble.


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