Data from: 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.