Continuous and discrete quantity discrimination in tortoises

Abstract

The study provide a new insight on numerical cognition in an ancient group of reptiles (chelonians), thus disclosing the early evolutionary acquisition of numerical ability in this group. Moreover, it is the second study conducted on reptiles, which are largely unexplored for numerical competence. AbstractThe ability to estimate quantity, which is crucially important in several aspects of animal behaviour (e.g., foraging), has been extensively investigated in most taxa, with the exception of reptiles. The few studies available, in lizards, report lack of spontaneous discrimination of quantity, which may suggest that reptiles could represent an exception in numerical abilities among vertebrates. We investigated the spontaneous ability of Hermann's tortoises (Testudo hermanni) to select the larger quantity of food items.Tortoises showed able to choose the larger food item when exposed with two options differing in size (0.25, 0.50, 0.67 and 0.75 ratio) and when presented with two groups differing in numerousness (1 versus 4, 2 versus 4, 2 versus 3 and 3 versus 4 items). The tortoises succeeded in both size and numerousness discrimination, and their performance appeared to depend on the ratio of items to be discriminated (thus following Weber's Law).These findings in chelonians provide evidence of an ancient system for the extrapolation of numerical magnitudes from given sets of elements, shared among vertebrates.

Absolute Numerosity Discrimination as a Case Study in Comparative Vertebrate Intelligence

“…Of course, one may argue that the blank spots of numeracy in the vertebrate phylogenetic tree will be filled with time and more investigations. After all, fish ( DeLong et al, 2017 ) amphibians ( Uller et al, 2003 ), and non-avian reptiles ( Gazzola et al, 2018 ) show relative numerical competence. In fact, some species of teleost fish show unexpected numerical ( Miletto et al, 2020 ) and cognitive skills ( Bloch et al, 2019 ) suggesting that they may also grasp absolute numerosity judgments.…”

Non-avian reptile learning 40 years on: advances and promising new directions

“…During extinction trials, with no food present, animals previously receiving large quantities took longer to extinguish responding than animals previously trained with less reward (Papini & Ishida, 1994). In a spontaneous discrimination test, Hermann's tortoises (Testudo hermanni) successfully chose the larger size and quantity of tomato (Gazzola et al, 2018) in four different combinations: 1 versus 4, 2 versus 4, 2 versus 3 and 3 versus 4 (ratios 0.25, 0.5, 0.67 and 0.75, respectively). Performance followed a ratio effect; the smaller the ratio the better accuracy in choosing the larger quantity/size of food.…”

Wolves and Dogs May Rely on Non-numerical Cues in Quantity Discrimination Tasks When Given the Choice

“…For example, assessing which areas have the most food and mating opportunities, as well as the fewest predators or competitors, often requires at least basic quantity judgment skills. Therefore, it is not surprising that a large array of species have demonstrated numerical competence to a certain extent ranging from insects ( Reznikova and Ryabko, 2011 ; Gatto and Carlesso, 2019 ), to cuttlefish ( Yang and Chiao, 2016 ); to vertebrates such as fish ( Agrillo et al, 2010 ; Gómez-Laplaza and Gerlai, 2011 ; Potrich et al, 2015 ), amphibians ( Krusche et al, 2010 ; Lucon-Xiccato et al, 2018 ), lizards ( Miletto Petrazzini et al, 2018 ), tortoises ( Gazzola et al, 2018 ), birds ( Hunt et al, 2008 ; Ditz and Nieder, 2016 ; Kelly, 2016 ), and mammals ( Hauser et al, 2003 ; Jordan and Brannon, 2006 ; Beran et al, 2008 ; Pisa and Agrillo, 2009 ; Irie and Hasegawa, 2012 ; Vonk and Beran, 2012 ).…”