[The solving of the Revecz-Krushinskiĭ test by Norway rats]

Reasoning abilities of Norway rats were studied in Revecz-Krushinskiĭ test. In this test 12 opaque plastic cylinders were placed in a row. Rats obtained the bait (sunflower seeds) after tipping the goal cylinder (from the feeder situated under it) independently of the number of one tipped before. Positions of the baits were changed in the following order: the cylinder No 1 in the first trial, No 2--in the second and so on up to the twelfth one. Rats were tested 3 times (12 trials, once a week) in a rectangular box with a starting chamber and a working part with a special device which excluded the influence of olfactory stimuli. Solution scores demonstrated that rats chose cylinders in the nonrandom manner and their behaviour scores were similar to those of crows and monkeys. Analysis of errors and strategies of behaviour of rats showed that quick improvement of feeding was at least partly determined by easy acquisition of recent food positions (i.e., the algorithm of shifting).