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Original article (peer-reviewed)

Journal Cognitive Development
Volume (Issue) 31
Page(s) 79 - 95
Title of proceedings Cognitive Development


There is substantial evidence for human infants’ use of 2 differentnumber processing systems, Object-File System and ApproximateNumber System; however, the majority of studies of non-humanprimates reveal processing via Approximate Number System only.The present study investigated whether apes use the Object-FileSystem when tested with an entity-first design, often used in infantstudies. Apes’ performance was consistently ratio-dependent andshowed no sign of an Object-File System, regardless of entity type(rigid and flexible cohesive objects vs. non-cohesive powder andliquid). After ruling out other low-level explanations, our resultssuggest that great apes relied solely on an Approximate NumberSystem. These results are discussed in light of a possible devel-opmental difference between human infants and adult great apes.