You have accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Boeckle M., Schiestl M., Frohnwieser A., Gruber R., Miller R., Suddendorf T., Gray R. D., Taylor A. H. and Clayton N. S. 2021New Caledonian crows' planning behaviour: a reply to de Mahy et al.Proc. R. Soc. B.2882021127120211271http://doi.org/10.1098/rspb.2021.1271SectionSupplemental MaterialYou have accessInvited replyNew Caledonian crows' planning behaviour: a reply to de Mahy et al. M. Boeckle M. Boeckle http://orcid.org/0000-0002-0738-2764 Department of Psychology, University of Cambridge, Cambridge, UK Scientific Working Group, Die offene Tür (The open door), Karl Landsteiner University of Health Sciences, Krems, Austria Department of Psychiatry and Psychotherapy, University Hospital Tulln, Tulln, Austria [email protected] Google Scholar Find this author on PubMed Search for more papers by this author , M. Schiestl M. Schiestl School of Psychology, University of Auckland, Auckland, New Zealand Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany Faculty of Veterinary Sciences, University of Veterinary Sciences, Brno, Czech Republic Google Scholar Find this author on PubMed Search for more papers by this author , A. Frohnwieser A. Frohnwieser http://orcid.org/0000-0001-5219-4319 Department of Psychology, University of Cambridge, Cambridge, UK Google Scholar Find this author on PubMed Search for more papers by this author , R. Gruber R. Gruber School of Psychology, University of Auckland, Auckland, New Zealand Google Scholar Find this author on PubMed Search for more papers by this author , R. Miller R. Miller http://orcid.org/0000-0003-2996-9571 Department of Psychology, University of Cambridge, Cambridge, UK Google Scholar Find this author on PubMed Search for more papers by this author , T. Suddendorf T. Suddendorf http://orcid.org/0000-0003-3328-7442 School of Psychology, University of Queensland, Saint Lucia, Queensland, Australia Google Scholar Find this author on PubMed Search for more papers by this author , R. D. Gray R. D. Gray http://orcid.org/0000-0002-9858-0191 School of Psychology, University of Auckland, Auckland, New Zealand Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany Google Scholar Find this author on PubMed Search for more papers by this author , A. H. Taylor A. H. Taylor School of Psychology, University of Auckland, Auckland, New Zealand Google Scholar Find this author on PubMed Search for more papers by this author and N. S. Clayton N. S. Clayton http://orcid.org/0000-0003-1835-423X Department of Psychology, University of Cambridge, Cambridge, UK Google Scholar Find this author on PubMed Search for more papers by this author M. Boeckle M. Boeckle http://orcid.org/0000-0002-0738-2764 Department of Psychology, University of Cambridge, Cambridge, UK Scientific Working Group, Die offene Tür (The open door), Karl Landsteiner University of Health Sciences, Krems, Austria Department of Psychiatry and Psychotherapy, University Hospital Tulln, Tulln, Austria [email protected] Google Scholar Find this author on PubMed Search for more papers by this author , M. Schiestl M. Schiestl School of Psychology, University of Auckland, Auckland, New Zealand Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany Faculty of Veterinary Sciences, University of Veterinary Sciences, Brno, Czech Republic Google Scholar Find this author on PubMed Search for more papers by this author , A. Frohnwieser A. Frohnwieser http://orcid.org/0000-0001-5219-4319 Department of Psychology, University of Cambridge, Cambridge, UK Google Scholar Find this author on PubMed Search for more papers by this author , R. Gruber R. Gruber School of Psychology, University of Auckland, Auckland, New Zealand Google Scholar Find this author on PubMed Search for more papers by this author , R. Miller R. Miller http://orcid.org/0000-0003-2996-9571 Department of Psychology, University of Cambridge, Cambridge, UK Google Scholar Find this author on PubMed Search for more papers by this author , T. Suddendorf T. Suddendorf http://orcid.org/0000-0003-3328-7442 School of Psychology, University of Queensland, Saint Lucia, Queensland, Australia Google Scholar Find this author on PubMed Search for more papers by this author , R. D. Gray R. D. Gray http://orcid.org/0000-0002-9858-0191 School of Psychology, University of Auckland, Auckland, New Zealand Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany Google Scholar Find this author on PubMed Search for more papers by this author , A. H. Taylor A. H. Taylor School of Psychology, University of Auckland, Auckland, New Zealand Google Scholar Find this author on PubMed Search for more papers by this author and N. S. Clayton N. S. Clayton http://orcid.org/0000-0003-1835-423X Department of Psychology, University of Cambridge, Cambridge, UK Google Scholar Find this author on PubMed Search for more papers by this author Published:01 September 2021https://doi.org/10.1098/rspb.2021.1271 Review history New Caledonian crows' planning behaviour: a reply to de Mahy et al. In our recent paper [1], we presented a novel test to show that New Caledonian crows can select tools in preparation for specific future events. The test consisted of a temporal sequence where the crows were (i) shown a baited apparatus that varied in the test condition between two tool-apparatus combinations, (ii) 5 min later given a choice between five objects and (iii) 10 min later given access to the apparatus. Crows were able to choose the right tool for each specific apparatus they had seen 5 min earlier. This experimental design allowed us to empirically evaluate the hypothesis that the amount of past reinforcement associated with different objects affects the choice of functional tools when subjects solve variants of the spoon test [2]. We argue that our results demonstrate that New Caledonian crows are an excellent candidate for testing the conservative criteria for mental time travel [3].In their comment, de Mahy et al. [4] argue that the crows in our study were able to solve the experiment irrespective of whether they had a ‘concept of the future’ or not. However, they do not capture all of the details of our experiment and interpretation accurately. The argument they make, as outlined in table 1 of their critique, substantially reduces actual task complexity by ignoring key aspects of the cognitive process required in our experiment. In Conditions 3 and 4, subjects have to note the apparatus identity, and then recall this 5 min later, despite recall for these specific apparatuses having not been rewarded in the past. Subjects then have to make the choice between one object that has been highly (and most recently) associated with a reward, the stick, and one of the two other functional tools (depending on the apparatus they observed 5 min before). The key question is whether the memory of an apparatus viewed 5 min before would be sufficient to motivate subjects to choose the correct tool over the more highly rewarded stick purely because of a past learnt association between a specific tool–apparatus combination, as de Mahy et al. argue. We believe this is a highly improbable possibility.Simply seeing a specific object in the environment should not then lead to an animal preferring an option that has been linked to less reinforcement over one that has been linked to more (the stone and hooks had been associated less with reward than the stick). This suggests that the future value of these tools drove the crows to ignore choosing the object associated with more reward in favour of one that had been previously associated with less reward—but would lead to a certain reward in the near future. Note how difficult this choice becomes on the second trial that the crows receive of our test conditions. At this point, they observe an apparatus, and then they are presented with: (i) a stick, which has been associated with food more than the other objects; (ii) a second tool that they have just been rewarded for using; and finally (iii) a third tool that they have never been rewarded for choosing after seeing an apparatus 5 min before. It seems highly unlikely that, at this point, our subjects would be motivated by their memory of the apparatus to choose the third, correct tool, rather than tools that had been associated more with reward, both generally (the stick), and in the immediate past (the second tool) unless they were aware of the utility of these tools for the upcoming situation.Mahy et al. also mis-characterize our interpretation of the study, claiming that we contrast associative explanations with the birds relying on a ‘higher-order concept of future planning’. Though their commentary repeatedly refers to ‘higher-order’ representations, we actually make no reference to such ideas in our paper, nor do we make claims about ‘the concept of the future’. The study was not aimed at testing for higher-order concepts of the future in New Caledonian crows. Instead, it was a pre-registered adversarial collaboration aimed at overcoming one of the key shortcomings of earlier studies on planning in animals. That shortcoming was that when animals could repeatedly select the same tool [5] simple associative accounts could explain their choices [6,7]. It had been suggested that one way to make a stronger case that animals can prepare for a specific future situation would be to present distinct future problems and give them a choice between objects that function as a solution in one condition and as distractors in another [8]. Our study did just that. We found that New Caledonian crows can indeed solve such a task, demonstrating sufficient flexibility in their choices to pick the right tool for the right future task, despite the presence of other tools that had been highly associated with food.In our paper, we did not, however, develop or defend a specific theory as to what cognitive processes drive this planning behaviour or make a case, much more broadly, about the relationship between associative processes and more complex cognition, or between richer and leaner accounts of observed behaviour. Several of us have written extensively on such issues [9–11] but resolving these fundamental questions of comparative psychology was not an aim of our collaboration and it is not the objective of this response either. Instead, we would like to remind the commentators that we explicitly acknowledged in our original publication that more work is required to determine what cognitive processes underpin this behaviour. Our study provides strong evidence against one specific alternative explanation of previous experiments using variants of the spoon test. Our experimental design goes well beyond simple observations of tool use or nest building in the wild, where the previous reinforcement histories of the birds are unknown and innate tendencies cannot be excluded. Nevertheless, evidence against one specific associative account does not mean we can jump to conclusions about specific cognitive mechanisms, as the authors appear to assume we did. Furthermore, we stated clearly in our paper that ‘we cannot completely rule out that crows chose the correct tool because of some kind of associative learning’. This caution reflects the nature of our adversarial, pre-registered collaboration: our study makes clear progress in this field but does not over-reach in its conclusions. We believe that such collaborations offer a highly promising avenue for resolving the many antagonistic debates within comparative psychology, and trust that, on this point, we can find agreement with Mahy and colleagues.EthicsThis article does not present research with ethical considerations.Data accessibilityThe paper is a commentary and not based on data.Authors' contributionsThis paper has multiple authors, and the individual contributions are shown below. Writing: M.B., R.M., T.S., A.H.T., N.S.C. Review and editing: M.B., M.S., A.F., R.G., R.M., T.S., R.D.G., A.H.T., N.S.C.All authors gave final approval for publication and agreed to be held accountable for the work performed therein.Competing interestsAll authors declare that they have no conflict of interests.FundingThis research was supported by the European Research Council under the European Union's Seventh Framework Programme (grant no. FP7/2007-2013)/ERC Grant Agreement no. 3399933 (N.S.C.), the Max Planck Institute for the Science of Human History (R.D.G.) and Australian Research Council Discovery grant no. DP210101572 (T.S.).AcknowledgementsThe authors appreciate the contribution of NÖ Landesgesundheitsagentur, legal entity of University Hospitals in Lower Austria, for providing the organizational framework to conduct this research.FootnotesThe accompanying comment can be viewed at http://doi.org/10.1098/rspb.2021.0186.© 2021 The Author(s)Published by the Royal Society. All rights reserved.