Ontogeny of Numerical Abilities in Fish

Abstract

BackgroundIt has been hypothesised that human adults, infants, and non-human primates share two non-verbal systems for enumerating objects, one for representing precisely small quantities (up to 3–4 items) and one for representing approximately larger quantities. Recent studies exploiting fish's spontaneous tendency to join the larger group showed that their ability in numerical discrimination closely resembles that of primates but little is known as to whether these capacities are innate or acquired.Methodology/Principal FindingsWe used the spontaneous tendency to join the larger shoal to study the limits of the quantity discrimination of newborn and juvenile guppies. One-day old fish chose the larger shoal when the choice was between numbers in the small quantity range, 2 vs. 3 fish, but not when they had to choose between large numbers, 4 vs. 8 or 4 vs. 12, although the numerical ratio was larger in the latter case. To investigate the relative role of maturation and experience in large number discrimination, fish were raised in pairs (with no numerical experience) or in large social groups and tested at three ages. Forty-day old guppies from both treatments were able to discriminate 4 vs. 8 fish while at 20 days this was only observed in fish grown in groups. Control experiments showed that these capacities were maintained after guppies were prevented from using non numerical perceptual variables that co-vary with numerosity.Conclusions/SignificanceOverall, our results suggest the ability of guppies to discriminate small numbers is innate and is displayed immediately at birth while discrimination of large numbers emerges later as a result of both maturation and social experience. This developmental dissociation suggests that fish like primates might have separate systems for small and large number representation.

Toward exact number: Young children use one-to-one correspondence to measure set identity but not numerical equality

“…For example, when given the instruction that one of two plates containing respectively 2 and 3 objects was ‘the winner’ (thus avoiding any reference to number words), children under 3 years could recognize the target numerosity after the objects were displaced, detected a change in number after the experimenter had surreptitiously added or removed an object from a plate, and even offered a solution to undo the change. These results were later extended in research with preverbal infants, who also proved able to detect a contrast between 2 and 3 objects (Feigenson et al, 2004; Féron, Gentaz, & Streri, 2006; Kobayashi, Hiraki, & Hasegawa, 2005; Kobayashi, Hiraki, Mugitani, & Hasegawa, 2004; Wynn, 1992; see Bisazza, Piffer, Serena, & Agrillo, 2010; Rugani, Fontanari, Simoni, Regolin, & Vallortigara, 2009, for a demonstration of the same abilities in newly hatched fish and chicks).…”

Evidence for Two Numerical Systems That Are Similar in Humans and Guppies

“…The inexperienced subjects were juvenile fish tested at the onset of their numerical abilities. A recent study showed that one-day-old guppies could discriminate the larger shoal when the choice was between numbers in the small number range, whereas the ability to discriminate large quantities appeared later, at approximately day 40 [37]. Thus, 100 one-day-old fish (20 in each numerical contrast) were tested in small quantity discrimination tasks, and 100 40-day-old fish were tested in large quantity discrimination tasks.…”

Guppies discriminate between two quantities of food items but prioritize item size over total amount

“…A number of different cues can be used to estimate shoal size. Experimental manipulation of these cues has shown that fish use density, cumulative area and amount of activity to estimate how numerous shoalmates are in a group (Agrillo, Dadda, Serena, & Bisazza, 2008;G omez-Laplaza & Gerlai, 2013a, 2013bPritchard, Lawrence, Butlin, & Krause, 2001), but that they can also base their choice solely on numerical information when they are prevented from using other cues (Bisazza, Piffer, Serena, & Agrillo, 2010;Dadda, Piffer, Agrillo, & Bisazza, 2009).…”