Wild capuchin monkeys select stone tools to crack open nuts on the basis of their weight and friability, two non-visual functional properties. Here we investigated whether they would select new stick-like tools on the basis of their rigidity. In Experiment 1 subjects faced an out-of-reach reward and a choice of three unfamiliar tools differing in colour, diameter, material, and rigidity. In order to retrieve the reward capuchins needed to select the rigid tool exemplar. Capuchins gathered information regarding tools pliability either by 1) manipulating the tools themselves (manipulation condition), 2) observing a human demonstrator repeatedly bending the tools (observation condition), or 3) seeing the tools placed on a platform without any manipulation taking place (visual static condition). Subjects selected the rigid tool above chance levels in both the manipulation and observation conditions, but not in the visual static condition. In Experiment 2 subjects needed to select and use a flexible tool to access a liquid reward (as opposed to the rigid tool, as in previous experiment). Again capuchins selected above chance levels the appropriate tool (i.e., flexible) thus demonstrating a good appreciation of the relation between the tool properties and the task requirements.
Tool choice on the basis of rigidity in capuchin monkeys
Springer., Berlin, Germania
Animal cognition (Print) 14 (2011): 775–786.
info:cnr-pdr/source/autori:Manrique, H. M., Sabbatini, G., Call, J., Visalberghi, E./titolo:Tool choice on the basis of rigidity in capuchin monkeys/doi:/rivista:Animal cognition (Print)/anno:2011/pagina_da:775/pagina_a:786/intervallo_pagine:775–786/volum