Department of Physics, Chemistry and Biology (IFM)

Study sites & animals

A total of 15 white-handed gibbons (Hylobates lar) was observed, of which seven were males and eight were females.The gibbons were observed in five different zoos, two in Sweden and three in the Netherlands. Data were collected in Kolmården Wildlife Park (Kolmården, Sweden), Parken Zoo (Eskilstuna, Sweden), Wildlands Adventure Zoo (Emmen, the Netherlands), Safaripark Beekse Bergen (Hilvarenbeek, the Netherlands), and Ouwehands Dierenpark (Rhenen, the Netherlands).

Definition of the studied motor patterns

Limb preferences for spontaneously occurring lateralized behavior as well as for an unimanual and bimanual tube task were observed. 

Spontaneously occurring behavior
Thirteen different spontenously occurring motor patterns were observed, these were divided in four categories: manipulation, leading limb, supporting hand, and resting position. The spontaneously occurring behaviors were all recorded continuously. 

Tube task
The tube task is a complex manual task which is often used to determine hand preference in nonhuman primates. An opaque tube is filled with edible content and presented to the animals. To extract the content from the inside of the tube, fine manipulation with one hand is required while the other hand (bimanual) or a foot (unimanual) is holding the tube. 

The sessions in which the tubes were presented were recorded on video to make sure that data for all gibbons could be collected.