School of Psychology, University of Chester, Parkgate Road, Chester, CH1 4BJ, UK.
Department of Psychology, Kyoto University Graduate School of Letters, Kyoto, Japan.
Anim Cogn. 2022 Aug;25(4):783-792. doi: 10.1007/s10071-021-01592-3. Epub 2022 Jan 7.
Mirror self-recognition (MSR), widely regarded as an indicator of self-awareness, has not been demonstrated consistently in gorillas. We aimed to examine this issue by setting out a method to evaluate gorilla self-recognition studies that is objective, quantifiable, and easy to replicate. Using Suarez and Gallup's (J Hum Evol 10:175-183, 1981) study as a reference point, we drew up a list of 15 methodological criteria and assigned scores to all published studies of gorilla MSR for both methodology and outcomes. Key features of studies finding both mark-directed and spontaneous self-directed responses included visually inaccessible marks, controls for tactile and olfactory cues, subjects who were at least 5 years old, and clearly distinguishing between responses in front of versus away from the mirror. Additional important criteria include videotaping the tests, having more than one subject, subjects with adequate social rearing, reporting post-marking observations with mirror absent, and giving mirror exposure in a social versus individual setting. Our prediction that MSR studies would obtain progressively higher scores as procedures and behavioural coding practices improved over time was supported for methods, but not for outcomes. These findings illustrate that methodological rigour does not guarantee stronger evidence of self-recognition in gorillas; methodological differences alone do not explain the inconsistent evidence for MSR in gorillas. By implication, it might be suggested that, in general, gorillas do not show compelling evidence of MSR. We advocate that future MSR studies incorporate the same criteria to optimize the quality of attempts to clarify the self-recognition abilities of gorillas as well as other species.
镜像自我识别（MSR）被广泛认为是自我意识的指标，但在大猩猩中并未得到一致证明。我们旨在通过提出一种客观、可量化且易于复制的方法来检验这个问题。以 Suarez 和 Gallup（J Hum Evol 10:175-183, 1981）的研究为参考点，我们列出了 15 项方法学标准，并对所有已发表的大猩猩 MSR 研究的方法和结果进行了评分。发现标记导向和自发自我导向反应的研究的关键特征包括标记无法被看到、控制触觉和嗅觉线索、被试年龄至少为 5 岁，以及清楚地区分在镜子前和远离镜子的反应。其他重要的标准包括对测试进行录像、有多个被试、被试有足够的社交养育、报告在没有镜子的情况下的标记后观察结果，以及在社交环境中而不是单独环境中进行镜子暴露。我们预测，随着时间的推移，程序和行为编码实践的改进，MSR 研究的得分会逐渐提高，这一预测得到了方法学的支持，但在结果方面却没有得到支持。这些发现表明，方法学严谨性并不能保证在大猩猩中更有力地证明自我识别；仅方法学差异并不能解释大猩猩中 MSR 不一致的证据。由此可以推断，一般来说，大猩猩并没有表现出令人信服的 MSR 证据。我们主张，未来的 MSR 研究应纳入相同的标准，以优化尝试澄清大猩猩以及其他物种自我识别能力的研究质量。
