Ebel, S. J., Kopp, K. S., Liebal, K. 2020. Object preferences in captive Sumatran orang-utans (Pongo abelii). Behavioural Processes 170, 103993.

While preferences for perceptual features of objects are well studied in humans, little is known about this trait in other great apes. We therefore presented captive Sumatran orang-utans (Pongo abelii) with objects that differed in shape (spherical, cuboid), colour (red, green), or texture (hard, soft). Overall, orang-utans preferred spherical over cuboid and red over green objects. Soft objects were preferred over hard ones. However, this preference might be confounded by the decomposable characteristic of soft objects since the orang-utans often unwrapped them. This study shows object preferences in orang-utans similar to those in humans, suggesting that perceptual preferences for basic object features such as shape and colour may be shared across primate species.