The representation of proportions in young domestic chicks

Non-verbal subjects –pre-verbal infants and non-human animals- can solve rudimentary mathematical operations (Vallortigara et al., 2010). Less emphasis has been given to the investigation of discrimination of continuous quantities, although a couple of studies with capuchin monkeys (vanMarle et al. 2006) and with chimpanzees (Beran, 2010) indicated that representation of continuous quantity may be performed similarly to representation of discrete quantity. Here we wanted to investigate if day-old domestic chicks (an animal model that is proved to master numerical discriminations, ordinality and arithmetic calculations, Rugani et al., 2010, 2011, 2013) can represent proportion of continuous quantities.