Is inferential reasoning a distinctly human cognitive feature? Testing reasoning in cotton-top tamarins (Saguinus oedipus).

Logical inference is often assumed a human-unique ability, although many species of apes and monkeys have shown some facility within a two-cup task in which one cup is baited, the primate is shown the cup which is empty (an exclusion cue), and subsequently chooses the other baited cup. In published reports, New World monkey species show a limited ability to choose successfully, often with half or more of the subjects tested not showing the ability with auditory cues or with exclusion cues. In this study, five cotton-top tamarins () were tested in a two-cup task with visual or auditory cues which revealed the presence or absence of bait, and in a second study, were tested with a four-cup array using a variety of walls to define the baiting space and a variety of visual cues including inclusion and exclusion.