String-pulling in Martin's spot-nosed monkey (Cercopithecus nictitans martini): evidence of physical continuity understanding.

In this study we tested an adult female Martin's spot-nosed monkey in several configurations of the string-pulling paradigm, including six different discrimination problems of patterned strings. Our subject solved almost all of the problems presented. Although she seemed to have a spatial preference in the most complex tasks, she maintained a high success rate in almost all of them. She also showed goal-directed behaviour that was not strictly based on visual feedback. Although more research is needed to understand better the subject's performance, we conclude that she showed clear signs of understanding physical continuity, and some degree of understanding of connectedness and causal relationships. [ABSTRACT FROM AUTHOR]