Young chicks rely on symmetry/asymmetry in perceptual grouping to discriminate sets of elements

A symmetry-based mechanism for perceptual grouping in preverbal infants

Newborn chicks can solve complex numerical discriminations through a purely perceptual mechanism based on the possibility of creating all equal-sized subsets. The present work investigates whether this is a prerogative of precocial birds or whether an analogous mechanism can be found in humans. We familiarized 8-month-olds with sets of even numerosities (i.e., decomposable in equal-sized subsets), and then we tested them for their spontaneous preference between two novel sets, one that cannot be divided into equal-sized subsets (i.e., a prime numerosity) and one decomposable in equal-sized subsets (i.e., a non-prime odd numerosity). Infants were tested with either the 7vs.9 comparison (i.e., the prime being smaller) or the 9vs.11 comparison (i.e., the prime being larger). Infants oriented their gaze more often toward the prime set of elements, irrespective of whether it was smaller or larger in the comparison, similar to the preference observed in baby chicks. Overall, our results suggest an early-emerging perceptual mechanism that can support complex numerical discriminations, that might be shared between distantly related and ecologically different species.

Through an animal's eye: the implications of diverse sensory systems in scientific experimentation

'Accounting for the sensory abilities of animals is critical in experimental design.' No researcher would disagree with this statement, yet it is often the case that we inadvertently fall for anthropocentric biases and use ourselves as the reference point. This paper discusses the risks of adopting an anthropocentric view when working with non-human animals, and the unintended consequences this has on our experimental designs and results. To this aim, we provide general examples of anthropocentric bias from different fields of animal research, with a particular focus on animal cognition and behaviour, and lay out the potential consequences of adopting a human-based perspective. Knowledge of the sensory abilities, both in terms of similarities to humans and peculiarities of the investigated species, is crucial to ensure solid conclusions. A more careful consideration of the diverse sensory systems of animals would improve many scientific fields and enhance animal welfare in the laboratory.

Here I am, why don't you answer me? Sensitivity to social responsiveness in domestic chicks

Newborn domestic chicks shortly exposed to a conspecific learn to recognize and prefer it over unfamiliar individuals. We assessed whether lack of physical contact or social feedback during familiarization affects affiliative preference, hypothesizing a crucial role of social responsiveness. Four-day-old chicks were tested for their preference between a familiar and an unfamiliar chick. In Exp. 1, we replicated the well-known preference for the familiar individual, even when (Exp. 2) a transparent glass prevented haptic interaction during familiarization. No preference was scored in Exp. 3, using a one-way glass, i.e., the subject could never be seen by its cagemate. The development of preferences toward a familiar but socially unresponsive cagemate was assessed by testing chicks twice (Exp. 4). While behaving at chance on day 2, birds showed a preference for the unfamiliar individual on day 4 of life. Our results highlight the importance of social interaction already in the first stages of life, irrespective of familiarity.

Are prime numbers special? Insights from the life sciences

Prime numbers have been attracting the interest of scientists since the first formulation of Euclid’s theorem in 300 B.C. Nowadays, physicists and mathematicians continue to formulate new theorems about prime numbers, trying to comprehensively explain their articulated properties. However, evidence from biology and experimental psychology suggest that prime numbers possess distinctive natural properties that pre-exist human grasping. The present work aims at reviewing the existing literature on prime numbers in the life sciences, including some recent experimental contributions employing newly hatched domestic chicks as animal model to test for spontaneous mechanisms allowing discrimination of primes from non-primes. Our overarching goal is that of discussing some instances of prime numbers in nature, with particular reference to their peculiar, non-mathematical, perceptual properties.