## If a fish can pass the mark test, what are the implications for consciousness and self-awareness testing in animals?

2019
##### Authors
Kohda, Masanori
Hotta, Takashi
Takeyama, Tomohiro
Awata, Satoshi
Tanaka, Hirokazu
Asai, Jun-Ya
Journal article
Published
##### Published in
PLoS biology ; 17 (2019), 2. - e3000021. - eISSN 1545-7885
##### Abstract
The ability to perceive and recognise a reflected mirror image as self (mirror self-recognition, MSR) is considered a hallmark of cognition across species. Although MSR has been reported in mammals and birds, it is not known to occur in any other major taxon. Potentially limiting our ability to test for MSR in other taxa is that the established assay, the mark test, requires that animals display contingency testing and self-directed behaviour. These behaviours may be difficult for humans to interpret in taxonomically divergent animals, especially those that lack the dexterity (or limbs) required to touch a mark. Here, we show that a fish, the cleaner wrasse Labroides dimidiatus, shows behaviour that may reasonably be interpreted as passing through all phases of the mark test: (i) social reactions towards the reflection, (ii) repeated idiosyncratic behaviours towards the mirror, and (iii) frequent observation of their reflection. When subsequently provided with a coloured tag in a modified mark test, fish attempt to remove the mark by scraping their body in the presence of a mirror but show no response towards transparent marks or to coloured marks in the absence of a mirror. This remarkable finding presents a challenge to our interpretation of the mark test—do we accept that these behavioural responses, which are taken as evidence of self-recognition in other species during the mark test, lead to the conclusion that fish are self-aware? Or do we rather decide that these behavioural patterns have a basis in a cognitive process other than self-recognition and that fish do not pass the mark test? If the former, what does this mean for our understanding of animal intelligence? If the latter, what does this mean for our application and interpretation of the mark test as a metric for animal cognitive abilities?
##### Subject (DDC)
570 Biosciences, Biology
##### Cite This
ISO 690KOHDA, Masanori, Takashi HOTTA, Tomohiro TAKEYAMA, Satoshi AWATA, Hirokazu TANAKA, Jun-Ya ASAI, Alex JORDAN, 2019. If a fish can pass the mark test, what are the implications for consciousness and self-awareness testing in animals?. In: PLoS biology. 17(2), e3000021. eISSN 1545-7885. Available under: doi: 10.1371/journal.pbio.3000021
BibTex
@article{Kohda2019-02impli-45338,
year={2019},
doi={10.1371/journal.pbio.3000021},
title={If a fish can pass the mark test, what are the implications for consciousness and self-awareness testing in animals?},
number={2},
volume={17},
journal={PLoS biology},
author={Kohda, Masanori and Hotta, Takashi and Takeyama, Tomohiro and Awata, Satoshi and Tanaka, Hirokazu and Asai, Jun-Ya and Jordan, Alex},
note={Article Number: e3000021}
}

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Yes
Yes