Ünver Emre, Garland Alexis, Tabrik Sepideh, Güntürkün Onur
Faculty of Psychology, Biopsychology, Ruhr University Bochum, 44780, Bochum, Germany.
Wallenberg Research Centre at Stellenbosch University, Stellenbosch Institute for Advanced Study (STIAS), Stellenbosch, 7600, South Africa.
Anim Cogn. 2017 Jul;20(4):677-688. doi: 10.1007/s10071-017-1090-x. Epub 2017 Apr 10.
A small number of species are capable of recognizing themselves in the mirror when tested with the mark-and-mirror test. This ability is often seen as evidence of self-recognition and possibly even self-awareness. Strangely, a number of species, for example monkeys, pigs and dogs, are unable to pass the mark test but can locate rewarding objects by using the reflective properties of a mirror. Thus, these species seem to understand how a visual reflection functions but cannot apply it to their own image. We tested this discrepancy in pigeons-a species that does not spontaneously pass the mark test. Indeed, we discovered that pigeons can successfully find a hidden food reward using only the reflection, suggesting that pigeons can also use and potentially understand the reflective properties of mirrors, even in the absence of self-recognition. However, tested under monocular conditions, the pigeons approached and attempted to walk through the mirror rather than approach the physical food, displaying similar behavior to patients with mirror agnosia. These findings clearly show that pigeons do not use the reflection of mirrors to locate reward, but actually see the food peripherally with their near-panoramic vision. A re-evaluation of our current understanding of mirror-mediated behavior might be necessary-especially taking more fully into account species differences in visual field. This study suggests that use of reflections in a mirrored surface as a tool may be less widespread than currently thought.
当用标记-镜子测试进行检测时，少数物种能够在镜子中认出自己。这种能力通常被视为自我识别甚至可能是自我意识的证据。奇怪的是，许多物种，例如猴子、猪和狗，无法通过标记测试，但却能利用镜子的反射特性找到有奖励的物体。因此，这些物种似乎理解视觉反射的功能，但却不能将其应用于自身形象。我们在鸽子身上测试了这种差异，鸽子是一种不会自发通过标记测试的物种。事实上，我们发现鸽子仅利用反射就能成功找到隐藏的食物奖励，这表明鸽子即使在没有自我识别的情况下，也能利用并可能理解镜子的反射特性。然而，在单眼条件下进行测试时，鸽子靠近并试图穿过镜子而不是靠近实际的食物，表现出与镜像失认症患者相似 的行为。这些发现清楚地表明，鸽子不是利用镜子的反射来定位奖励，而是实际上用它们近乎全景的视觉从周边看到食物。可能有必要重新评估我们目前对镜像介导行为的理解，尤其是要更充分地考虑视野中的物种差异。这项研究表明，将镜面反射用作工具的情况可能比目前认为的要少。
