title: Object permanence in orangutans (Pongo pygmaeus), chimpanzees (Pan troglodytes), and children (Homo sapiens).
abstract: Juvenile and adult orangutans (n = 5; Pongo pygmaeus), chimpanzees (n = 7; Pan troglodytes), and 19- and 26-month-old children (n = 24; Homo sapiens) received visible and invisible displacements. Three containers were presented forming a straight line, and a small box was used to displace a reward under them. Subjects received 3 types of displacement: single (the box visited 1 container), double adjacent (the box visited 2 contiguous containers), and double nonadjacent (the box visited 2 noncontiguous containers). All species performed at comparable levels, solving all problems except the invisible nonadjacent displacements. Visible displacements were easier than invisible, and single were easier than double displacements. In a 2nd experiment, subjects saw the baiting of either 2 adjacent or 2 nonadjacent containers with no displacements. All species selected the empty container more often when the baited containers were nonadjacent than when they were adjacent. It is hypothesized that a response bias and inhibition problem were responsible for the poor performance in nonadjacent displacements.
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany. call@eva.mpg.de
authors.forename: J
authors.initials: J
authors.lastname: Call
mesh_terms: D000818:Animals; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007266:Inhibition, Psychological; D008297:Male; D008568:Memory; D002679:Pan troglodytes / Q000523:psychology*; D011148:Pongo pygmaeus / Q000523:psychology*; D011340:Problem Solving; D013028:Space Perception; D013045:Species Specificity