Selection and transport of tools to crack open nuts by semifree-ranging capuchin monkeys (Cebus apella): experimental manipulation of costs, quality of "hammers" and the distance between "hammers" and "anvils".

• Grant number: 09/03223-5
• Support Opportunities: Scholarships in Brazil - Master
• Start date: September 01, 2009
• End date: December 31, 2010
• Field of knowledge: Humanities - Psychology - Experimental Psychology
• Principal Investigator: Eduardo Benedicto Ottoni
• Grantee: Bianca de Oliveira Fonseca
• Host Institution: Instituto de Psicologia (IP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The spontaneous use of tools by capuchin monkeys has been studied by the Laboratory of Cognitive Ethology in wild and semifree-ranging groups. In the Tietê Ecological Park, the use of stones to crack open jerivá's nuts has been the target of naturalistic studies for over a decade. Recently, we start to study this behavior also through "experimental interventions" to deepen our understanding of various aspects of the selection and transport of the tools employed by the animals. The present study extends these experiments, evaluating tool selectivity of the monkeys as a function of "hammers" properties (shape and weight) and the effects of the distance between available "anvils" and "hammers" on this selectivity. We will analyze the effect of coespecifics' presence on the simutaneous transport of coconuts and "hammers", a peculiarity previously observed in the behavior of our subjects (and seen by some authors as a result of cognitive limitations), which, we suppose, may result from an "audience effect" associated with the risk of theft of these resources.

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

FONSECA, Bianca de Oliveira. Selection and transport of tools to crack open nuts by semifree-ranging capuchin monkeys (Sapajus sp): experimental manipulation of the costs of the distance between \hammers\ and \anvils\ and efficiency of the tool. 2012. Master's Dissertation - Universidade de São Paulo (USP). Instituto de Psicologia (IP/SBD) São Paulo.