Wild capuchins feed on high-energy husked fruits. Field researchers suggested that capuchins select beforehand the fruits which are worthwhile to crack open. We assessed whether captive capuchins use sound and/or weight as proximal causes to infer the fullness of a nut (full nuts are heavier and produce a low pitched frequency sound when tapped). Two subjects had to choose between a nut shell containing food and another nut shell without food differing in weight and sound (phase 1), or weight (phases 2 and 4), or sound (phase 3). Both subjects readily solved phase 1 and 2. The only subject who spontaneously finger-tapped on the nut shells solved phase 3. The minimal difference in weight perceived ranged between 2.1 and 3 g. Therefore, as expected by ecological psychology and optimal foraging theory, data suggest that capuchins seek information to discriminate effectively between full and empty nuts before going through the costly opening process.
Tufted capuchins (Cebus apella) use weight and sound to choose between full and empty nuts.
Lawrence Erlbaum Associates,, Hillsdale, N.J. , Stati Uniti d'America
Ecological psychology 15 (2003): 215–228.
info:cnr-pdr/source/autori:Visalberghi E., Neel.C./titolo:Tufted capuchins (Cebus apella) use weight and sound to choose between full and empty nuts./doi:/rivista:Ecological psychology/anno:2003/pagina_da:215/pagina_a:228/intervallo_pagine:215–228/volume: