Representing tools: how two non-human primate species distinguish between the functionally relevant and irrelevant features of a tool.
Few studies have examined whether non-human tool-users understand the properties that are relevant for a tool's function. We tested cotton-top tamarins (Saguinus oedipus) and rhesus macaques (Macaca mulatta) on an expectancy violation procedure designed to assess whether these species make distinctions between the functionally relevant and irrelevant features of a tool. Subjects watched an experimenter use a tool to push a grape down a ramp, and then were presented with different displays in which the features of the original tool (shape, color, orientation) were selectively varied. Results indicated that both species looked longer when a newly shaped stick acted on the grape than when a newly colored stick performed the same action, suggesting that both species perceive shape as a more salient transformation than color. In contrast, tamarins, but not rhesus, attended to changes in the tool's orientation. We propose that some non-human primates begin with a predisposition to attend to a tool's shape and, with sufficient experience, develop a more sophisticated understanding of the features that are functionally relevant to tools.
Department of Psychology, Harvard University, Cambridge, MA 02138, USA. laurie.santos@yale.edu
Laurie R
LR
Santos
Cory T
CT
Miller
Marc D
MD
Hauser
D000818:Animals; D004193:Discrimination Learning; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D007100:Imitative Behavior; D008253:Macaca mulatta / Q000254:growth & development* / Q000523:psychology*; D008297:Male; D009048:Motor Skills; D011214:Practice, Psychological; D012452:Saguinus / Q000254:growth & development* / Q000523:psychology*; D013045:Species Specificity