Humboldt-Universität zu Berlin Dissertation Great Apes’ Causal Cognition in the Physical Domain Zur Erlangung des akademischen Grades Doctor rerum naturalium Mathematisch-Naturwissenschaftliche Fakultät II Daniel Hanus Dekan: Prof. Dr. Peter Frensch Gutachter: 1. Prof. Dr. Elke van der Meer, Humboldt-Universität, Berlin 2. Prof. Dr. Michael Tomasello, Max Planck Institut für evolutionäre Anthropologie, Leipzig 3. Dr. Josep Call, Max Planck Institut für evolutionäre Anthropologie, Leipzig eingereicht: 04. August 2009 Datum der Promotion: 03. Dezember 2009 1 Table of content Zusammenfassung .................................................................................................................... 4 Summary ................................................................................................................................... 5 Acknowledgements ................................................................................................................... 6 List of original publications ..................................................................................................... 7 GENERAL INTRODUCTION ............................................................................................... 8 Prologue ................................................................................................................................. 8 General approach .................................................................................................................... 9 Causal cognition in children ................................................................................................. 10 Causal cognition in animals ................................................................................................. 13 Causal cognition in primates ................................................................................................ 14 Outline studies ...................................................................................................................... 16 STUDY I .................................................................................................................................. 18 Comparing the performances of apes and humans in the floating peanut task ............... 18 Abstract ................................................................................................................................ 19 Introduction .......................................................................................................................... 20 Experiment 1: ......................................................................................................................... 22 Leipzig chimpanzees and gorillas ........................................................................................ 22 Method ................................................................................................................................. 22 Subjects ............................................................................................................................ 22 Apparatus and procedure .................................................................................................. 22 Results .................................................................................................................................. 23 Discussion ............................................................................................................................ 23 Experiment 2: ......................................................................................................................... 25 Sanctuary orangutans and chimpanzees ............................................................................... 25 Method ................................................................................................................................. 25 Subjects ............................................................................................................................ 25 Apparatus and procedure .................................................................................................. 25 Experimental phase .......................................................................................................... 26 Control phase .................................................................................................................... 26 Results .................................................................................................................................. 27 Experimental phase .......................................................................................................... 27 Control phase .................................................................................................................... 28 Discussion ............................................................................................................................ 30 Experiment 3: ......................................................................................................................... 32 Functional fixedness ............................................................................................................. 32 Method ................................................................................................................................. 32 Subjects ............................................................................................................................ 32 Apparatus and procedure .................................................................................................. 33 2 Results .................................................................................................................................. 33 Discussion ............................................................................................................................ 35 Experiment 4: ......................................................................................................................... 36 Children ................................................................................................................................ 36 Method ................................................................................................................................. 36 Participants ....................................................................................................................... 36 Apparatus and procedure .................................................................................................. 36 Results .................................................................................................................................. 37 Discussion ............................................................................................................................ 38 General discussion ................................................................................................................ 39 STUDY II ................................................................................................................................ 46 Contrasting the use of causal and arbitrary cues in chimpanzee problem solving .......... 46 Abstract ................................................................................................................................ 47 Introduction .......................................................................................................................... 47 Method ................................................................................................................................. 49 Subjects ............................................................................................................................ 49 Materials ........................................................................................................................... 49 Procedure .......................................................................................................................... 49 Results .................................................................................................................................. 51 Discussion ............................................................................................................................ 53 STUDY III ............................................................................................................................... 56 Chimpanzees infer the location of a reward on the basis of the effect of its weight ........ 56 Original article ........................................................................................................................ 57 Supplemental data .................................................................................................................. 62 Experimental methods .......................................................................................................... 62 Subjects ............................................................................................................................ 62 Materials ........................................................................................................................... 62 Procedure .......................................................................................................................... 62 Analysis details .................................................................................................................... 63 GENERAL DISCUSSION ....................................................................................................