Sense of Self in Magpies

In a paper published in PLoS Biology by Prior et al. in late 2008, research suggested that magpies have a rudimentary sense of self. This conclusion was supported by experiments that evaluated five magpies with mark and mirror tests. Three of the magpies showed self-recognition behavior rather than the social or aggressive behavior usually displayed by most animals except humans, primates, and a few other known exceptions.

Past Studies on Animal Sense of Self. In 1977, Gordon G. Gallup, Jr., published a pioneering study outlining an explicit test for self-recognition by exposing animals to mirrors. His original experiments yielded support that chimpanzees and orangutans show self-directed behavior; therefore, they display a sense of self. Up until this study, no other animals had displayed a sense of self except for humans (past infancy).

Reiss and Marino (2001) studied bottlenose dolphins and found similar results with two dolphins who were marked on parts of their body not visible without the aid of a reflective surface. Reiss also contributed to a study with Plotnik et al. (2006) that found similar results in Asian elephants using a mark and mirror test to determine if they could achieve mirror self-recognition. Recent research would suggest that these animals have self-awareness because their brains have developed to a point where they have learning and memory capabilities that, in conjunction with sensory input, leads to a sense of self. (Tannenbaum 2008).

Why Magpie? Certain birds have shown the ability to use tools, have episodic-like memory, and use past experiences to predict behaviors in other birds of the same species. Although these traits are not indicators of a sense of self, they demonstrate birds’ intellectual capacities despite having diverged from primates 300 million years ago.

In particular, European magpies (Pica pica) were chosen because they:
1) hoard food and store it for future consumption, which illustrates their memory abilities.
2) have achieved the highest level of Piagetian object permanence, which surprisingly cannot be attained by monkeys.
3) demonstrate their social intelligence not only with food storage, but their general tendencies to be curious creatures.

The Task at Hand. Five magpies housed in two-compartment cages and exposed to four experimental conditions based on Gallup’s mirror tests conducted with chimpanzees.
1) The bird was marked with a bright color (yellow or red) and placed in a cage with a mirror.
2) The bird was marked with a bright color and placed in a cage with a non-reflective plate where the mirror would have been placed.
3) The bird was marked with a black mark on its throat, which has black feathers, and placed in the cage with mirror.
4) Surprise! The bird was marked with a black mark and placed in the cage with the plate.

Magpie mirror test video

The five birds, Gerti, Goldie, Harvey, Lilly, and Schatzi, were subjected to each of the four trials. When initially placed in front of the mirror, the magpies demonstrated typical social behaviors. Gerti, Goldie, and Schatzi all “showed at least one instance of spontaneous self-directed behavior” during the mark and mirror test. The figure to the left shows Gerti's activity towards the brightly colored mark (orange bar) and black mark (black bar) with and without a mirror present.

So... why does this matter? Sense of self does not simply appear in humans; rather, it is acquired along with other abilities as has been discussed by developmental theorists and outlined in detail with the use of experimental tasks (Bertenthal & Fischer 1978). Still, questions of consciousness and self-awareness, their necessity, and their origins are not completely clear. Studies on animal sense of self alter our view of their brains and capabilities despite evolving separately for millions of years. However, there are a number of issues that arise in the experimental procedure for testing sense of self with the mirror test. Many of the studies cited had small samples of only a handful of animals, especially the controversial studies on elephants, dolphins, and the birds discussed here. In the case of the magpies, two birds did not show self-recognizing behavior. To cement these findings, further studies must be conducted to produce generalizable results.

Bibliography

Bertenthal, B. I. & Fischer, K. W. (1978). Developmental of self-recognition in the infant. Developmental Psychology 14(1), 44-50.
Gallup, G. G. (1977). Self-recognition in primates: A comparative approach to the bidirectional properties of consciousness. American Psychologist, 329-338.
Plotnik, J. M., de Waal, F. B. M., & Reiss, D. (2006). Self-recognition in an Asian elephant. Proceedings of the National Academy of the Sciences 103(45), 17053-17057.
Prior, H., Schwarz, A., & Gunturkun, O. (2008). Mirror-induced behavior in the magpie (Pica pica): Evidence of self-recognition. PLoS Biology 6(8), 1642-1650.
Reiss, D. & Marino, L. (2001). Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence. Proceedings of the National Academy of the Sciences of the United States of America 98(10), 5937-5942.
Tannenbaum, E. (2008). Speculations on the emergence of self-awareness in big-brained organisms: The roles of associative memory and learning, existential and religious questions, and the emergence of tautologies. Consciousness and Cognition, 1-14.