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Kerry Jordan, Joseph Baker, Kati Rodzon, John Shivik; Tracking of food quantities by coyotes (Canis Latrans). Journal of Vision 2010;10(7):238. doi: 10.1167/10.7.238.
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© ARVO (1962-2015); The Authors (2016-present)
What types of visual quantitative competencies do nonhuman animals possess, in the absence of linguistic labels for quantity? A wealth of previous studies have identified approximate systems of number representation in various species, suggesting that we may share with other species a rough nonverbal numerical competence. Previous studies have demonstrated that the numerical discrimination abilities across these various species—including the nonverbal representations of humans—are mediated by the ratio between numerical options; such approximate systems of quantification have been dubbed ‘analog magnitude’ representations of number (see Brannon and Roitman, 2003, for one review). The current experiment is the first to specifically test coyotes' quantitative discrimination abilities. In particular, we tested semi free-ranging coyotes' ability to discriminate between large and small quantities of food items and investigated whether this ability conforms to predictions of Weber's Law. We demonstrate herein that coyotes can reliably discriminate between large versus small quantities of food. As predicted by Weber's Law, coyotes' numerical discrimination abilities are mediated by the numerical ratio between the large and small quantities of food. This trend is indicative of an analog magnitude system of number representation. Furthermore, in this task, coyotes were not discriminating large versus small quantities based on olfactory cues alone; instead, they were visually tracking quantity. Our results also indicate that coyotes do not show evidence of learning effects within this task; in other words, they do not perform better on trials completed first, compared to trials completed last. In the future, we plan to conduct this same study with domestic dogs, in order to compare visual quantitative sensitivity between these two closely related species.
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