Through the looking glass: how do marked dolphins use mirrors and what does it mean?

Alina Loth, Onur Güntürkün, Lorenzo von Fersen, Vincent M. Janik*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Downloads (Pure)


Mirror-guided self-inspection is seen as a cognitive hallmark purportedly indicating the existence of self-recognition. Only a few species of great apes have been reported to pass a standard mark test for mirror self-recognition in which animals attempt to touch a mark. In addition, evidence for passing the mark test was also reported for Asian elephants, two species of corvids, and a species of cleaner fish. Mirror self-recognition has also been claimed for bottlenose dolphins, using exposure of marked areas to a mirror as evidence. However, what counts as self-directed behaviour to see the mark and what does not has been debated. To avoid this problem, we marked the areas around both eyes of the animals at the same time, one with visible and the other with transparent dye to control for haptic cues. This allowed the animal to see the mark easily and us to investigate what side was exposed to the mirror as an indicator for mark observation. We found that the animals actively chose to inspect their visibly marked side while they did not show an increased interest in a marked conspecific in the pool. These results demonstrate that dolphins use the mirror to inspect their marks and, therefore, likely recognise a distinction between self and others.
Original languageEnglish
Number of pages10
JournalAnimal Cognition
VolumeOnline First
Early online date20 Sept 2022
Publication statusE-pub ahead of print - 20 Sept 2022


  • Self-recognition
  • Theory of mind
  • Consciousness
  • Bottlenose dolphin
  • Tursiops truncatus


Dive into the research topics of 'Through the looking glass: how do marked dolphins use mirrors and what does it mean?'. Together they form a unique fingerprint.

Cite this