Plotnik JM, de Waal FBM, Reiss D. Self-recognition in an Asian elephant. Proc. Natl. Acad. Sci. Published online before print October 30, 2006.
Considered an indicator of self-awareness, mirror self-recognition (MSR) has long seemed limited to humans and apes. In both phylogeny and human ontogeny, MSR is thought to correlate with higher forms of empathy and altruistic behavior. Apart from humans and apes, dolphins and elephants are also known for such capacities. After the recent discovery of MSR in dolphins (Tursiops truncatus), elephants thus were the next logical candidate species. We exposed three Asian elephants (Elephas maximus) to a large mirror to investigate their responses. Animals that possess MSR typically progress through four stages of behavior when facing a mirror: (i) social responses, (ii) physical inspection (e.g., looking behind the mirror), (iii) repetitive mirror-testing behavior, and (iv) realization of seeing themselves. Visible marks and invisible sham-marks were applied to the elephants' heads to test whether they would pass the litmus "mark test" for MSR in which an individual spontaneously uses a mirror to touch an otherwise imperceptible mark on its own body. Here, we report a successful MSR elephant study and report striking parallels in the progression of responses to mirrors among apes, dolphins, and elephants. These parallels suggest convergent cognitive evolution most likely related to complex sociality and cooperation.
Moti Nissani, Donna Hoefler-Nissani. Absence of Mirror Self-Referential Behavior in Two Asian Elephants.
To date, one investigation failed to find mirror self-referential behavior in Asian elephants while another reported positive results, a contradiction which could, among other things, be ascribed to the poor visual acuity of elephants. To resolve this contradiction, the present study of mirror self-referential behavior in two captive Asian elephants bypasses the traditional mark test, relying instead on the elephants’ response to a far more visually conspicuous object. In this study, neither elephant engaged in self-referential behavior in front of a mirror. Our simple experimental paradigm could serve as a more convenient alternative to the widely used traditional mark test, could meet some methodological objections which have been raised against the traditional mark test, and could profitably augment the traditional test in difficult or controversial cases.
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