title: The discrimination of discrete and continuous amounts in African grey parrots (Psittacus erithacus).
abstract: A wealth of research in infants and animals demonstrates discrimination of quantities, in some cases nonverbal numerical perception, and even elementary calculation capacities. We investigated the ability of three African grey parrots (Psittacus erithacus) to select the largest amount of food between two sets, either discrete food items (experiment 1) or as volume of a food substance (experiment 2). The two amounts were presented simultaneously and were visible at the time of choice. Parrots were tested several times for all possible combinations between 1 and 5 seeds or 0.2 and 1 ml of food substance. In both conditions, subjects performed above chance for almost all combinations. Accuracy was negatively correlated with the ratio, that is performance improved with greater differences between amounts. Therefore, these results with both individual items and volume discrimination suggest that parrots use an analogue of magnitude, rather than object-file mechanisms to quantify items and substances.
authors.affiliation: Laboratoire d'Ethologie et de Cognition Comparée, Université Paris X-Nanterre, 200, Avenue de la République, 92001, Nanterre cedex, France.
authors.forename: Syrina Al
authors.initials: SA
authors.lastname: Aïn
authors.forename: Nicolas
authors.initials: N
authors.lastname: Giret
authors.forename: Marion
authors.initials: M
authors.lastname: Grand
authors.forename: Michel
authors.initials: M
authors.lastname: Kreutzer
authors.forename: Dalila
authors.initials: D
authors.lastname: Bovet
mesh_terms: D000818:Animals; D016009:Chi-Square Distribution; D003210:Concept Formation; D004193:Discrimination Learning; D005260:Female; D008297:Male; D055641:Mathematical Concepts; D008433:Mathematics; D010311:Parrots; D011340:Problem Solving; D018709:Statistics, Nonparametric