Assessing quantity combination and dissociation in giraffes.

Several species have demonstrated the ability to mentally manipulate quantities in tasks requiring their combination and dissociation, reflecting perceptual memory-based mechanisms that may be the foundation of proto-arithmetic and in some cases more advanced arithmetic abilities. Yet, ungulates remain underrepresented in this line of research. Here, we present the first investigation in giraffes (Giraffa camelopardalis) assessing their ability to combine and dissociate quantities. We tested four captive giraffes in three experimental and two controls tasks. In the experimental tasks, the animals could only see the initial quantities and the items moved, but not the final amounts. Results revealed that giraffes performed above chance in the Combination task (where food was combined to one of two covered quantities). However, they performed at chance level in both the Dissociation task (where food was removed from one of two covered quantities) and the Subsequent Events task (where food was transferred from one of the two quantities to the other one). Further analyses suggested that while two subjects might have relied on simpler strategies (e.g., choosing or avoiding the dish manipulated by the experimenter), the other two succeeded even when this strategy could not be used, suggesting the potential use of more complex mental computations.