Department of Physics, Chemistry and Biology (IFM)

Three adult female black-handed spider monkeys (Ateles geoffroyi) were used in this study.

The study was conducted at the research station Pipiapan run by the Universidad Veracruzana outside of Catemaco, Veracruz, in Mexico. 

Testing was carried out using a two-choice instrumental conditioning paradigm, in which the animals are presented with two options, one correct and one incorrect. 

On top of each lid was a metal clip attached. This clip helt a 70 x 10 mm absorbent paper strip which was impregnanted with 20 μ l  of the odorant or the odorless control substance. 

To determine olfactory detection thresholds, the monkeys were presented with 10-fold increasing dilutions of an odorant used as the rewarded stimulus (S+) until they failed to discriminate it from the odorless solvent used as unrewarded stimulus (S-).