The central nervus system stabilizes unstable dynamics by learning optimal impedance

letters to nature 446 NATURE |VOL 414 |22 NOVEMBER 2001 |www. nature. com between the birds was their experience in the earlier observational learning study14 Ð observer, pilferer or observer + pilferer. These categories are directly related to the... More

letters to nature 446 NATURE |VOL 414 |22 NOVEMBER 2001 |www. nature. com between the birds was their experience in the earlier observational learning study14 Ð observer, pilferer or observer + pilferer. These categories are directly related to the speci®c experiences in the previous experiment, not the developmental histories of the birds. Although we cannot state that birds in the pilferer group had never observed other birds cache they did not do so in the previous study or in the current one. Importantly, the observer birds have never pilfered another bird s caches. The observer + pilferer (n = 7) group was ®rst tested at the University of California, Davis (19±26 July 2000), with a replicate study performed at the University of Cambridge (15 January to 16 February 2001). Birds in the observer (n = 7) and pilferer (n = 7) groups were tested at Cambridge (15 January to 16 February 2001). The interleaved trials study (observer + pilferer group only) was per Less