Use of ordinal information by fish.
Mammals and birds can process ordinal numerical information which can be used, for instance, for recognising an object on the basis of its position in a sequence of similar objects. Recent studies have shown that teleost fish possess numerical abilities comparable to those of other vertebrates, but it is unknown if they can also learn ordinal numerical relations. Guppies (Poecilia reticulata) learned to recognise the 3(rd) feeder in a row of 8 identical ones even when inter-feeder distance and feeder positions were varied among trials to prevent the use of any spatial information. To assess whether guppies spontaneously use ordinal or spatial information when both are simultaneously available, fish were then trained with constant feeder positions and inter-feeder distance. In probe trials where these two sources of information were contrasted, the subjects selected the correct ordinal position significantly more often than the original spatial position, indicating that the former was preferentially encoded during training. Finally, a comparison between subjects trained on the 3(rd) and the 5(th) position revealed that guppies can also learn the latter discrimination, but the larger error rate observed in this case suggests that 5 is close to the upper limit of discrimination in guppies.
Dipartimento di Psicologia Generale, Università di Padova, Italy.
Maria Elena Miletto
ME
Petrazzini
Dipartimento di Psicologia Generale, Università di Padova, Italy.
Tyrone
T
Lucon-Xiccato
Dipartimento di Psicologia Generale, Università di Padova, Italy.|Centro di Neuroscienze Cognitive, Università di Padova, Italy.
Christian
C
Agrillo
Dipartimento di Psicologia Generale, Università di Padova, Italy.|Centro di Neuroscienze Cognitive, Università di Padova, Italy.
Angelo
A
Bisazza
D000818:Animals; D005247:Feeding Behavior; D005399:Fishes / Q000502:physiology*