Date of Award

Spring 5-2018

Degree Type


Degree Name

Doctor of Philosophy (PhD)



Committee Chair

Tammy Greer

Committee Chair Department


Committee Member 2

Alen Hajnal

Committee Member 2 Department


Committee Member 3

Elena Stepanvoa

Committee Member 3 Department


Committee Member 4

Lawrence Patihis

Committee Member 4 Department



An abundance of behavioral and neuroimaging literature supports the presence of two cognitive systems for quantity judgments (Agrillo & Bisazza, 2014). In particular, small quantities are thought to be guided by the object-file system, a precise system that uses mental files to map onto real world objects, and large quantities by the approximate number system, an imprecise, estimation system (Dehaene, 1997). Evidence supporting both systems exists in a variety of species including nonhuman primates (Boysen & Hallberg, 2000), birds (Garland, Low, & Burns, 2012), amphibians (Uller, Jaeger, Guidry, & Martin, 2003), and fish (Agrillo, Dadda, Serena, Bisazza, 2009), but support may depend on species and on method of assessment. The purpose of this meta-analysis was to examine differences in the extent of support for object-file versus the approximate number systems, to determine whether type of task affects quantity judgment, and to delineate species differences in abilities to distinguish quantities. Results revealed some success in both large and small set sizes and in both large and small ratio manipulation categories and supported the use of both the approximate number system and the object file system across species. Moderator analyses revealed no effect of the type of task on the proportion of correct judgments during quantity discrimination tasks. Findings support the overall hypothesis that there is not one single quantity judgment system, but rather there is a combination of the approximate number and object file systems plus a role of experience with the environment. Species differences are discussed.