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Animal cognition2021; 24(5); 1099-1108; doi: 10.1007/s10071-021-01502-7

If horses had toes: demonstrating mirror self recognition at group level in Equus caballus.

Abstract: Mirror self-recognition (MSR), investigated in primates and recently in non-primate species, is considered a measure of self-awareness. Nowadays, the only reliable test for investigating MSR potential skills consists in the untrained response to a visual body mark detected using a reflective surface. Here, we report the first evidence of MSR at group level in horses, by facing the weaknesses of methodology present in a previous pilot study. Fourteen horses were used in a 4-phases mirror test (covered mirror, open mirror, invisible mark, visible colored mark). After engaging in a series of contingency behaviors (looking behind the mirror, peek-a-boo, head and tongue movements), our horses used the mirror surface to guide their movements towards their colored cheeks, thus showing that they can recognize themselves in a mirror. The analysis at the group level, which 'marks' a turning point in the analytical technique of MSR exploration in non-primate species, showed that horses spent a longer time in scratching their faces when marked with the visible mark compared to the non-visible mark. This finding indicates that horses did not see the non-visible mark and that they did not touch their own face guided by the tactile sensation, suggesting the presence of MSR in horses. Although a heated debate on the binary versus gradualist model in the MSR interpretation exists, recent empirical pieces of evidence, including ours, indicate that MSR is not an all-or-nothing phenomenon that appeared once in phylogeny and that a convergent evolution mechanism can be at the basis of its presence in phylogenetically distant taxa.
© 2021. The Author(s).
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Publication Date: 2021-03-13 PubMed ID: 33713273PubMed Central: PMC8360890DOI: 10.1007/s10071-021-01502-7Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article investigates mirror self-recognition (MSR) in horses, analyzing potential self-awareness in this animal group. The results indicate horses may be capable of MSR, a characteristic previously mainly attributed to primates.

Overview of the Research and Methodology

  • The researchers perform a study involving 14 horses and a 4-phase mirror test. The aim of this analysis is to examine whether horses demonstrate self-recognition when seeing their reflection in a mirror.
  • The mirror test comprises four stages: a covered mirror phase, an open mirror phase, an invisible mark phase, and a visible colored mark phase.
  • Before the test, weaknesses in previous research methods regarding MSR in horses were addressed to improve the methodology used in this study.

Observational Results

  • Horses exhibited unique behaviors in response to their reflection, such as looking behind the mirror, performing head and tongue movements, and engaging in a peek-a-boo action. Both actions presumably showed attempts to understand and react to the image in the mirror.
  • Additionally, the horses used the reflective surface of the mirror to guide their movements towards their colored cheeks, hinting at the possibility of them recognizing themselves.

Group-Level Analysis

  • Analysis at the group level indicated that horses spent more time scratching their faces when marked with a visible color in contrast to when they had a non-visible mark.
  • These observations suggest that the horses did not see the non-visible mark. Moreover, it implies they didn’t touch their face based on tactile sensation, further pointing towards the possibility of MSR in horses.

Discussion and Conclusions

  • The study indicates that MSR may not be restricted to primates and could also be displayed by non-primate species such as horses.
  • Despite debates about whether MSR is a binary (either present or absent) or gradualist (varies in degree) model, the results from this research suggest that MSR may not be an all-or-nothing phenomenon, and can occur through a process of convergent evolution in various phylogenetically disparate taxa.

Cite This Article

APA
(2021). If horses had toes: demonstrating mirror self recognition at group level in Equus caballus. Anim Cogn, 24(5), 1099-1108. https://doi.org/10.1007/s10071-021-01502-7

Publication

Animal cognition
ISSN: 1435-9456
NlmUniqueID: 9814573
Country: Germany
Language: English
Volume: 24
Issue: 5
Pages: 1099-1108

Researcher Affiliations

MeSH Terms

  • Animals
  • Behavior, Animal
  • Horses
  • Pilot Projects
  • Recognition, Psychology
  • Toes
  • Touch

Grant Funding

  • 599999_2017_FFABR / University of Pisa

Conflict of Interest Statement

The authors declare that the research was conducted without any conceptual or financial relationships that could represent a potential conflict of interest.

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Citations

This article has been cited 8 times.
  1. Tomberg C, Petagna M, de Selliers de Moranville LA. Horses (Equus caballus) facial micro-expressions: insight into discreet social information. Sci Rep 2023 May 27;13(1):8625.
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  2. Baciadonna L, Cornero FM, Clayton NS, Emery NJ. Mirror stimulation in Eurasian jays (Garrulus glandarius). PeerJ 2023;11:e14729.
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  3. Scopa C, Maglieri V, Baragli P, Palagi E. Getting rid of blinkers: the case of mirror self-recognition in horses (Equus caballus). Anim Cogn 2022 Aug;25(4):711-716.
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  4. Gallup GG Jr, Anderson JR. Putting the cart before the horse: claims for mirror self-recognition in horses are unfounded. Anim Cogn 2022 Feb;25(1):1-4.
    doi: 10.1007/s10071-021-01538-9pubmed: 34313872google scholar: lookup
  5. Kohda M, Sogawa S, Bshary R. On the mirror test and the evolutionary origin of self-awareness in vertebrates. Philos Trans R Soc Lond B Biol Sci 2025 Nov 13;380(1939):20240312.
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