There is controversy in comparative psychology about whether on the one hand non-symbolic number estimation of small (≤4) and large numbers involves a single mechanism (an approximate number system), or whether on the other hand enumeration of the numbers 1–4 is accomplished by a separate mechanism, an object tracking system. To date, support for the latter hypothesis has come only from the different ratio-dependency of performance seen in the two numerical ranges, a reading that has been criticized on several grounds. In humans, the two-system hypothesis is supported by evidence showing that manipulation of the physical properties of the stimuli (e.g., the motion of the items) has dissimilar effects on small- and large-number discrimination. In this research, we studied this effect on guppies. Initially, fish were trained to simultaneously discriminate two numerical contrasts having the same easy ratio (0.50): one in the small-number (2 vs. 4) range and one in the large-number (6 vs. 12) range. Half of the fish were presented with moving items; the other half were shown the same stimuli without motion. Fish were then subjected to non-reinforced probe trials in the presence of a more difficult ratio (0.75: 3 vs. 4 and 9 vs. 12). Under both static and moving conditions, the fish significantly discriminated 6 versus 12, but not 9 versus 12 items. As regards small numbers, both groups learned to discriminate a 0.50 ratio, but only fish tested with moving stimuli also discriminated 3 and 4 items. This differential effect suggests that fish may possess two separate systems for small- and large-number discrimination.
OTS ANS Subitizing Numerical cognition Continuous variables Guppies
This is a preview of subscription content, log in to check access.
This study was supported by the “Progetto Giovani Studiosi 2010” (prot.: GRIC101125) research grant, given by the University of Padua to Christian Agrillo; and by PRIN 2009 (Prin (2009WZXK7T), given by MIUR to Angelo Bisazza. The reported experiments comply with all of the laws of the country (Italy) in which they were performed.
Agrillo C, Dadda M, Serena G (2008a) Choice of female groups by male mosquitofish (Gambusia holbrooki). Ethology 114(5):479–488CrossRefGoogle Scholar
Agrillo C, Dadda M, Serena G, Bisazza A (2008b) Do fish count? Spontaneous discrimination of quantity in female mosquitofish. Anim Cogn 11:495–503PubMedCrossRefGoogle Scholar
Assad JA, Maunsell JHR (1995) Neuronal correlates of inferred motion in primate posterior parietal cortex. Nature 373:518–521PubMedCrossRefGoogle Scholar
Beran MJ (2004) Chimpanzees (Pan troglodytes) respond to nonvisible sets after one-by-one addition and removal of items. J Comp Psychol 118:25–36PubMedCrossRefGoogle Scholar
Beran MJ (2008a) The evolutionary and developmental foundations of mathematics. PLoS Biol 6:221–223CrossRefGoogle Scholar
Beran MJ (2008b) Monkeys (Macaca mulatta and Cebus apella) track, enumerate, and compare multiple sets of moving items. J Exp Psych Anim Behav Proc 34:63–74CrossRefGoogle Scholar
Beran MJ, Evans TA, Leighty KA, Harris EH, Rice D (2008) Summation and quantity judgments of sequentially presented sets by capuchin monkeys (Cebus apella). Am J Primatol 70:191–194PubMedCrossRefGoogle Scholar
Beran MJ, McIntyre JM, Garland A, Evans TA (2013) What counts for “counting”? Chimpanzees (Pan troglodytes) respond appropriately to relevant and irrelevant information in a quantity judgment task. Anim Behav 85:987–993PubMedCrossRefGoogle Scholar
Gross HJ, Pahl M, Si A, Zhu H, Tautz J, Zhang S (2009) Number-based visual generalisation in the honeybee. PLoSONE 4:e4263CrossRefGoogle Scholar
Halberda J, Mazzocco M, Feigenson L (2008) Individual differences in nonverbal number acuity predict maths achievement. Nature 455:665–668PubMedCrossRefGoogle Scholar
Hauser MD, Spelke ES (2004) Evolutionary and developmental foundations of human knowledge: a case study of mathematics. In: Gazzaniga M (ed) The cognitive neurosciences, vol 3. MIT Press, CambridgeGoogle Scholar
Hauser MD, Carey S, Hauser LB (2000) Spontaneous number representation in semi-free-ranging rhesus monkeys. Proc R Soc Lond B 267:829–833CrossRefGoogle Scholar
Hunt S, Low J, Burns KC (2008) Adaptive numerical competency in a food-hoarding songbird. Proc R Soc Lond B 275:2373–2379CrossRefGoogle Scholar
Matsuno T, Tomonaga M (2006) Visual search for moving and stationary items in chimpanzees (Pan troglodytes) and humans (Homo sapiens). Behav Brain Res 172:219–232PubMedCrossRefGoogle Scholar
Miletto Petrazzini ME, Agrillo C, Piffer L, Dadda M, Bisazza A (2012) Development and application of a new method to investigate cognition in newborn guppies. Behav Brain Res 233:443–449PubMedCrossRefGoogle Scholar
Miletto Petrazzini ME, Agrillo C, Piffer L, Bisazza A (2013) Ontogeny of the capacity to compare discrete quantities in fish. Dev Psychobiol, online first, doi:10.1002/dev.21122
Neisser U (1967) Cognitive psychology. Prentice-Hall, Englewood CliffsGoogle Scholar
Perdue BM, Talbot CF, Stone A, Beran MJ (2012) Putting the elephant back in the herd: elephant relative quantity judgments match those of other species. Anim Cogn 15:955–961PubMedCrossRefGoogle Scholar