CAPACITIES FOR TRANSITIVE INFERENCE IN BI RDS - GILLAN TEST SOLUTION IN CORVIDS AND PIGEONS

Transitive inference in birds was investigated using D. J. Gillan (198 1) experimental procedure. In the initial experiment 11 pigeons and 14 crows were trained to differentiate colour stimuli in pairs of adjace nt ones from five-stimulus succession A, B, C, D, and E. The birds lea rned that stimulus E was associated with more food items than D, D, in turn, signalled less food items than C, and so on. Then the birds wer e tested by newly formed pairs of stimuli from the same succession (BD , CE, and BE). There were two series of testing. Both crows and pigeon s solved the transitive inference test successfully (chosing D and E) in the series with small numbers of food items. In the series with lar ger numbers of food items the pigeons shifted to random performance wh ile in crows the percentage of correct choices decreased. The proporti on of adequate test solutions grew with the absolute difference betwee n the numbers of food items associated with stimuli to compare. The ca pacity for solving the test in our experiments can be considered as th e result of immediate comparison of the absolute numbers of food items associated with each stimulus. Thus, the data cannot be regarded as t he final proof that these species are capable for transitive inference .