Abstract
The question of whether some non-human animal species are more intelligent than others is a reoccurring theme in comparative psychology. To convincingly address this question, exact comparability of behavioral methodology and data across species is required. The current article explores one of the rare cases in which three vertebrate species (humans, macaques, and crows) experienced identical experimental conditions during the investigation of a core cognitive capability – the abstract categorization of absolute numerical quantity. We found that not every vertebrate species studied in numerical cognition were able to flexibly discriminate absolute numerosity, which suggests qualitative differences in numerical intelligence are present between vertebrates. Additionally, systematic differences in numerosity judgment accuracy exist among those species that could master abstract and flexible judgments of absolute numerosity, thus arguing for quantitative differences between vertebrates. These results demonstrate that Macphail’s Null Hypotheses – which suggests that all non-human vertebrates are qualitatively and quantitatively of equal intelligence – is untenable.
Highlights
Intelligence, broadly defined, is the general capacity to solve problems (Macphail, 1987)
Whether non-human vertebrate species differ in intelligence remains hotly debated in comparative psychology
The quantitative parameters derived from the neuronal tuning functions, such as the widths of the tuning functions, are comparable between monkeys and crows (Nieder and Miller, 2003; Ditz and Nieder, 2015). All these findings argue that primates and crows engage the same approximate number system” (ANS) when representing absolute numerosity
Summary
Intelligence, broadly defined, is the general capacity to solve problems (Macphail, 1987). Absolute numerosity discriminations have been investigated in different vertebrate species using a delayed match-tonumerosity task (DMNT) (Figure 1A; Nieder et al, 2002). In the DMNT, motivated subjects discriminate numerosities that are carefully controlled for non-numerical features for reward (Figure 1B).
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call