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Two strings to choose from: do ravens pull the easier one?

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Abstract

There are simple co-occurrences as well as functional relationships between events. One may assume that animals detect and use causation rather than mere co-variation. However, understanding causation often requires concepts of hidden forces. In string pulling, obstacles may hamper the access to food. Here, I studied whether ravens have an abstract concept of effort. First, in a competitive situation, ravens (Corvus corax) could choose one out of two strings. The strings differed in whether they were baited with meat and in how far away the meat was. Ravens pulled mainly the string containing meat and where the meat was nearer to the perch, respectively. Second, ravens could choose between two strings that had either a functional obstacle or a non-functional obstacle. Optimal performance required the integration of at least two cues: object and height. In 5 ravens, the model that best matched behaviour took into account only that meat was on a string, ignoring the obstacle. However, 2 ravens’ performance was best explained by a model that took into account both an object’s identity (meat or wood) and its height on the string. Third, one string out of two was loaded with a heavy meat piece. In this overloaded string condition, 5 out of 7 ravens did not try to pull the heavy meat piece but went straight for pulling the smaller piece. The pattern of results indicated that ravens can judge the effort required to pull a string.

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Notes

  1. The pandanus tools are used to retrieve invertebrates from trees. Insertion of something and pulling it out is common to both the natural and the trap-tube task. Letting something fall has no parallel in the NC crows’ natural environment.

  2. This result holds even if it is based on all 62 trials and 18 errors, because bird N and C never made an error.

  3. The inter-rater reliability for the duration was 0.96 and for the type of string pulled 1. Rater two scored one session per day and bird for experiment 2, n = 33.

References

  • Betsch T, Haberstroh S, Molter B, Glockner A (2004) Oops, I did it again—relapse errors in routinized decision making. Organ Behav Hum Decis Process 93:62–74

    Article  Google Scholar 

  • Brown MF (1990) The effects of maze-arm length on performance in the radial-arm maze. Anim Learn Behav 18(1):13–22

    Article  Google Scholar 

  • Bugnyar T, Heinrich B (2005) Ravens, Corvus corax, differentiate between knowledgeable and ignorant competitors. Proc R Soc B Biol Sci 272:1641–1646

    Article  Google Scholar 

  • Bugnyar T, Kotrschal K (2004) Leading a conspecific away from food in ravens (Corvus corax)? Anim Cogn 7:69–76

    Article  PubMed  Google Scholar 

  • Chittka L, Dyer AG, Bock F, Dornhaus A (2003) Psychophysics—bees trade off foraging speed for accuracy. Nature 424:388

    Article  PubMed  CAS  Google Scholar 

  • Clayton NS, Dally JM, Emery NJ (2007) Social cognition by food-caching corvids. The western scrub-jay as a natural psychologist. Philos Trans R Soc B 362:507–522

    Article  Google Scholar 

  • Emery NJ (2009) Cognitive ornithology: the evolution of avian intelligence. Philos Trans R Soc B 361:23–43

    Article  Google Scholar 

  • Emery NJ, Clayton NS (2004) The mentality of crows: convergent evolution of intelligence in corvids and apes. Science 306:1903–1907

    Article  PubMed  CAS  Google Scholar 

  • Halsey LG, Bezerra BM, Souto AS (2006) Can wild common marmosets (Callithrix jacchus) solve the parallel strings task? Anim Cogn 9:229–233

    Article  PubMed  CAS  Google Scholar 

  • Hanus D, Call J (2008) Chimpanzees infer the location of a reward on the basis of the effect of its weight. Curr Biol 18(9):R370–R372

    Article  PubMed  CAS  Google Scholar 

  • Hanus D, Mendes N, Tennie C, Call J (2011) Comparing the performance of apes (Gorilla gorilla, Pan troglodytes, Pongo pygmaeus) and human children (Homo sapiens) in the floating peanut task. PLoS One 6:e19555

    Article  PubMed  CAS  Google Scholar 

  • Hare B, Call J, Tomasello M (2004) Chimpanzees are more skillful in competitive than in cooperative cognitive tasks. Anim Behav 68:571–581

    Article  Google Scholar 

  • Heinrich B (1995) An experimental investigation of insight in common ravens (Corvus corax). Auk 112:994–1003

    Google Scholar 

  • Heinrich B, Bugnyar T (2005) Testing problem solving in ravens: string-pulling to reach food. Ethology 111:962–976

    Article  Google Scholar 

  • Hunt GR, Gray RD (2003) Diversification and cumulative evolution in New Caledonian crow tool manufacture. Proc R Soc Lond Ser B Biol Sci 270:867–874

    Article  Google Scholar 

  • Jones LV, Fiske DW (1953) Models for testing the significance of combined results. Psychol Bull 50:375–382

    Article  PubMed  CAS  Google Scholar 

  • Kirsch JA, Gunturkun O, Rose J (2008) Insight without cortex: lessons from the avian brain. Conscious Cogn 17:475–483

    Article  PubMed  Google Scholar 

  • Koehler DJ, James G (2009) Probability matching in choice under uncertainty: intuition versus deliberation. Cognition 113:123–127

    Article  PubMed  Google Scholar 

  • Liedtke J, Werdenich D, Gajdon GK, Huber L, Wanker R (2011) Big brains are not enough: performance of three parrot species in the trap-tube paradigm. Anim Cogn 14:143–149

    Article  PubMed  Google Scholar 

  • Martin-Ordas G, Call J, Colmenares F (2008) Tubes, tables and traps: great apes solve two functionally equivalent trap tasks but show no evidence of transfer across tasks. Anim Cogn 11:423–430

    Article  PubMed  Google Scholar 

  • Mendes N, Hanus D, Call J (2007) Raising the level: orangutans use water as a tool. Biol Lett 3:453–455

    Article  PubMed  Google Scholar 

  • Mulcahy NJ, Call J, Dunbar RIM (2005) Gorillas (Gorilla gorilla) and Orangutans (Pongo pygmaeus) encode relevant problem features in a tool-using task. J Comp Psychol 119(1):23–32

    Article  PubMed  Google Scholar 

  • Osthaus B, Lea SEG, Slater AM (2005) Dogs (Canis lupus familiaris) fail to show understanding of means-end connections in a string-pulling task. Anim Cogn 8:37–47

    Article  PubMed  Google Scholar 

  • Povinelli DJ (2000) Folk physics for apes: the chimpanzee’s theory of how the world works. Oxford University Press, Oxford

    Google Scholar 

  • Schrauf C, Call J (2011) Great apes use weight as a cue to find hidden food. Am J Primatol 73(4):323–334.

    Article  PubMed  Google Scholar 

  • Schuck-Paim C, Borsari A, Ottoni EB (2009) Means to an end: neotropical parrots manage to pull strings to meet their goals. Anim Cogn 12:287–301

    Article  PubMed  Google Scholar 

  • Schwab C, Bugnyar T, Schloegl C, Kotrschal K (2008) Enhanced social learning between siblings in common ravens, Corvus corax. Anim Behav 75:501–508

    Article  Google Scholar 

  • Seed AM, Tebbich S, Emery NJ, Clayton NS (2006) Investigating physical cognition in rooks, Corvus frugilegus. Curr Biol 16:697–701

    Article  PubMed  CAS  Google Scholar 

  • Sloman SA (2005) Causal models: how we think about the world and its alternatives. Oxford University Press, New York

    Google Scholar 

  • Stowe M, Bugnyar T, Loretto M-C, Schloegl C, Range F, Kotrschal K (2006) Novel object exploration in ravens (Corvus corax): effect of social relationships. Behav Process 73:68–75

    Article  Google Scholar 

  • Taylor AH, Hunt GR, Holzaider JC, Gray RD (2007) Spontaneous metatool use by New Caledonian crows. Curr Biol 17:1504–1507

    Article  PubMed  CAS  Google Scholar 

  • Taylor AH, Hunt GR, Medina FS, Gray RD (2009) Do New Caledonian crows solve physical problems through causal reasoning? Proc R Soc B Biol Sci 276:247–254

    Article  CAS  Google Scholar 

  • Taylor AH, Medina FS, Holzaider JC, Hearne LJ, Hunt GR, Gray RD (2010) An investigation into the cognition behind spontaneous string pulling in New Caledonian Crows. PLoS One 5:e9345. doi:10.1371/journal.pone.0009345

    Article  PubMed  Google Scholar 

  • Tebbich S, Seed AM, Emery NJ, Clayton NS (2007) Non-tool-using rooks, Corvus frugilegus, solve the trap-tube problem. Anim Cogn 10:225–231

    Article  PubMed  Google Scholar 

  • Tomasello M (2000) Two hypotheses about primate cognition. In: Heyes CM, Huber L (eds) The evolution of cognition. MIT Press, Cambridge

    Google Scholar 

  • Visalberghi E, Limongelli L (1994) Lack of comprehension of cause-effect relations in tool-using capuchin monkeys (Cebus apella). J Comp Psychol 108:15–22

    Article  PubMed  CAS  Google Scholar 

  • Visalberghi E, Néel C (2003) Tufted capuchins (Cebus apella) use weight and sound to choose between full and empty nuts. Ecol Psychol 15:215–228

    Article  Google Scholar 

  • Visalberghi E, Addessi E, Truppa V, Spagnoletti N, Ottoni E, Izar P, Fragaszy D (2009) Selection of effective stone tools by wild capuchin monkeys. Curr Biol 19:213–217

    Article  PubMed  CAS  Google Scholar 

  • Weir AAS, Chappell J, Kacelnik A (2002) Shaping of hooks in new Caledonian crows. Science 297:981

    Article  PubMed  CAS  Google Scholar 

  • Werdenich D, Huber L (2006) A case of quick problem solving in birds: string pulling in keas, Nestor notabilis. Anim Behav 71:855–863

    Article  Google Scholar 

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Acknowledgments

I thank the people at the Konrad Lorenz Research station for their support. The work was supported by the Verein der Förderer der Konrad Lorenz Forschungsstelle and the Cumberland Wildpark where the study has been carried out. I also thank B. Pfuhl for video scoring and U. Toelch and R. Biegler for helpful discussions. The paper was greatly improved by the comments and language advice from three anonymous referees.

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  1. Department of Psychology, NTNU, Trondheim, Norway

    Gerit Pfuhl

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  1. Gerit Pfuhl
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Correspondence to Gerit Pfuhl.

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Pfuhl, G. Two strings to choose from: do ravens pull the easier one?. Anim Cogn 15, 549–557 (2012). https://doi.org/10.1007/s10071-012-0483-0

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