Solution of Revecz-Krushinskii test by animals of different taxonomic groups

Abstract

There has been compared behavior of rats, corvid birds, and monkeys of different species at their performance of the Revecz-Krushinskii test (RKT) developed by L.V. Krushinskii to estimate the human capability for revealing rule of discrete translocation of hidden target object. RKT was introduced as an addition to the test for extrapolation of the movement direction of the lure seen only at the initial pathway fragment; this test is close to Piaget’s test (stage 6) evaluating the capability for mental representation and location of the moving hidden object. During RKT, the lure, hidden from animals, was placed, near where it was previous time: at the first test presentation—under the 1st cylinder, at the 2nd one—under the 2nd cylinder, etc. The animals were tested once. It was shown that they did not catch the necessary for successful solution rule of the lure translocation, direction and step of its translocation at each presentation. Only some of the animals solved RKT, found the lure 3 and more times in succession with no errors or with one error. Nevertheless, in all groups the number of errors was lower than that in the model situation of random search. Such optimization was a consequence of universal for all groups’ strategy of search in the places where the lure was found recently. With the similar number of errors, rats, birds, and monkeys performed the search differently. Rats were looking for lure mainly among the cylinders where they had found it previously, whereas monkeys and birds the first the new cylinders located near the target one, which implies the existence, to the weak extent, of elements of prognosis. For all groups of animals, RKT turned out to be more difficult both of the test for extrapolation and of the Piaget’s test.