title: Apes communicate about absent and displaced objects: methodology matters.
abstract: Displaced reference is the ability to refer to an item that has been moved (displaced) in space and/or time, and has been called one of the true hallmarks of referential communication. Several studies suggest that nonhuman primates have this capability, but a recent experiment concluded that in a specific situation (absent entities), human infants display displaced reference but chimpanzees do not. Here, we show that chimpanzees and bonobos of diverse rearing histories are capable of displaced reference to absent and displaced objects. It is likely that some of the conflicting findings from animal cognition studies are due to relatively minor methodological differences, but are compounded by interpretation errors. Comparative studies are of great importance in elucidating the evolution of human cognition; however, greater care must be taken with methodology and interpretation for these studies to accurately reflect species differences.
authors.affiliation: Department of Psychology, University of Southern Mississippi, Gulf Coast 730 East Beach Blvd., Long Beach, MS, 39560, USA, heidi.lyn@usm.edu.
authors.forename: Heidi
authors.initials: H
authors.lastname: Lyn
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Russell
authors.forename: David A
authors.initials: DA
authors.lastname: Leavens
authors.forename: Kim A
authors.initials: KA
authors.lastname: Bard
authors.forename: Sarah T
authors.initials: ST
authors.lastname: Boysen
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Schaeffer
authors.forename: William D
authors.initials: WD
authors.lastname: Hopkins
mesh_terms: D000819:Animal Communication; D000818:Animals; D005260:Female; D008297:Male; D019974:Pan paniscus / Q000523:psychology*; D002679:Pan troglodytes / Q000523:psychology*