Chimpanzees recognize their own delayed self-image

Unlike mirror self-recognition, recognizing one's own image in delayed video footage may indicate the presence of a concept of self that extends across time and space. While humans typically show this ability around 4 years of age, it is unknown whether this capacity is found in non-human animals. In this study, chimpanzees performed a modified version of the mark test to investigate whether chimpanzees could remove stickers placed on the face and head while watching live and delayed video images. The results showed that three of five chimpanzees consistently removed the mark in delayed-viewing conditions, while they removed the stickers much less frequently in control video conditions which lacked a link to their current state. These findings suggest that chimpanzees, like human children at the age of 4 years and more, can comprehend temporal dissociation in their concept of self.