New paper on lovebird symbol learning and numerical ability is out!

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Link

Abstract

Cognitive capacity for associative learning and quantity discrimination is highly adaptive in various ecological contexts and subject to convergent evolution across diverse animal species. Discrimination accuracy generally increases with the ratio between two quantities in many studied animals; however, this ability is expected to vary among species, highlighting the need to understand how it operates in different taxa. Parrots are among the most intelligent birds, but only a few parrot species have been studied for their associative learning and quantity discrimination abilities. To investigate these cognitive capabilities in small parrots, we presented a novel symbol system to 28 rosy-faced lovebirds, Agapornis roseicollis. This system associates additive tally marks with symbols representing a one-to-one correspondence with different food quantities. We specifically tested three aspects of cognition related to numerical competence, namely associative learning, inference and quantity discrimination. Trained lovebirds could spontaneously infer the relative food quantities represented by other symbols. Lovebirds proved capable of (1) associating symbols (i.e. object-file symbolism) with (2) ‘more-less’ quantity inference by deducing food quantities based on their knowledge of this symbol-quantity association and (3) enhancing their performance in relation to disparity ratio (conforming to Weber's law) and absolute difference. Furthermore, (4) the influence of food ratios and absolute differences varied with different ratio ranges. Within a small ratio range (≤3), increasing the ratio or absolute difference enhanced discrimination performance. However, within a higher ratio range (>3), these characteristics had less of an impact. We concluded that rosy-faced lovebirds are capable of advanced associative learning and quantity discrimination, similar to larger parrot species.