Ring-Tailed Lemurs (Lemur Catta) Chose Objects on the Basis of Their Colour and Shape or According to the Lemurs' Lateralization?

Some studies about the colour vision in ring-tailed lemurs (Lemur catta) revealed that lemurs behave trichromatically. They can differentiate greens, blues and reds. Trichromacy provides an important advantage for fruit eating species, indeed it can be a valuable aid in determining when fruit is ripe. However, whether the food is fruit or leaves, the ability to see reds would make it easier to pick out a food target in a green vegetation background. New research sheds light on how primates, including man, evolved the ability to see red and green. Is there an advantage in being able to differentiate different shapes and not only colours? Furthermore is there an advantage in differentiating objects on the basis of their colour and shape? How and how much the position of an objects can influence the subjects' preference? This research aimed to answer these questions. Thus, two different groups of lemurs hosted at Parco Natura Viva, Bussolengo (VR), Italy, were employed with four different boxes, a green rectangular box and a red one, a triangular box and square one. There were 8 different combinations of the boxes to see the preference of each subject for the colour, shape and their own laterality. The results showed that there is a preference at a population level for the object with a particular shape, the square shape. Furthermore, some of the subjects showed a preference for the first interaction for the box placed on the same side and few subjects preferred to take the pellet from the box on the same side.