No evidence of what-where-when memory in great apes (Pan troglodytes, Pan paniscus, Pongo abelii, and Gorilla gorilla).

Abstract

Episodic memory is the ability to recollect specific past events belonging to our personal experience, and it is one of the most crucial human abilities, allowing us to mentally travel through time. In animals, however, evidence of what-where-when memory (hereafter, WWW memory) is limited to very few taxa, mostly reflecting the socioecological challenges faced in their environment. In this article, we aimed to replicate 2 studies previously conducted on birds and primates to find convincing evidence of WWW memory in great apes. For this purpose, we tested 12 captive great apes in 3 different tasks. In Task 1, we tested whether great apes take into account temporal information when choosing between highly preferred perishable and less-preferred nonperishable food items. In Task 2, we tested whether great apes can differentiate between similar events having happened at different times in the past. Finally, in Task 3, we tested whether great apes can use their memory flexibly, incorporating novel information in their memories. In none of the tasks did our subjects make the correct choice significantly above chance, with performance further declining when subjects were presented with 2 events (Task 2). Moreover, none of them could reliably integrate novel information into their memories. Overall, our study casts doubt on the existence of WWW memory in great apes, and especially calls for more caution when using WWW memory tasks and interpreting their results. (PsycInfo Database Record (c) 2020 APA, all rights reserved).