Music Preference and Discrimination in Three Sumatran Orangutans (Pongoabelii) Sarah E. Ritvo a Thesis Submitted to the Faculty
Total Page：16
File Type：pdf, Size：1020Kb
MUSIC PREFERENCE AND DISCRIMINATION IN THREE SUMATRAN ORANGUTANS (PONGOABELII) SARAH E. RITVO A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS GRADUATE PROGRAM IN PSYCHOLOGY YORK UNIVERSITY TORONTO, ONTARIO August 2013 © Sarah E. Ritvo, 2013 l' . ABSTRACT This investigation assessed musical preference and discriminative ability in three Sumatran orangutans. In Study 1, preferences for music vs. silence were examined in three phases. In Phase I, subjects made choices via touchscreen to replay a previously sounded music exemplar or listen to silence instead. In Phase II, subjects could "shuffle" between music exemplars and/or silence exemplars through touchscreen contact. In Phase III, subjects could produce musical notes by touching the keys on a virtual piano. In Study 2, subjects' ability to discriminate 'music' from 'scrambled music' was tested using a touchscreen-delivered delayed matching-to-sample task. Results indicate subjects preferred silence to music (or were indifferent) and that they could not discriminate 'music' from 'scrambled music', suggesting orangutans do not find musk reinforcing and/or do not perceive music the way humans do. Consequently, the use of music as environmental enrichment in captive primate facilities appears unfounded and may be aversive rather than enriching. ii ACKNOWLEDGEMENTS First, I would like to thank my graduate supervisor, Dr. Suzanne MacDonald, for her guidance and supervision, for numerous encouraging and delicious lunch dates, and for enthusiastically and graciously providing me with the opportunity to live out a dream that I have harbored since childhood. Second, I would like to thank my lab mates, Heidi Marsh, Laura Adams and Catherine Reeve for their support, mentorship, and inspiring shared passion for comparative cognition. I would also like to sincerely thank Dr. Joel Katz for his continuous support and indispensable analytical guidance and insight into the intricacies of my methodologies and data, as well as Dr. Jennine 'Rawana and Dr. Amro Zayed for their participation in my thesis committee. This project would not have been possible without the support of the Toronto Zoo and its staff. Thank you for your assistance and tolerance (I'm sorry if I ruined the music used in these studies for you forever!) I would particularly like to. thank Jacqueline Craig and Matthew Berridge for bravely volunteering their voices to be ;.used as stimuli. To the orangutans at the Toronto Zoo, Sekali, Kembali, Ramai, Jingga, Puppe and Budi, I am forever grateful for your patience, your wit, your slapstick comedic relief and for your unexpected and touching displays of friendship. Finally, I would like to acknowledge the infinite and unconditional love and support of my parents, Paul and Janet Ritvo and my partner, James Kitts. None of this would have been possible without you. Thank you for encouraging me to pursue my dreams and for your unwavering belief in my ability to do so. iii TABLE OF CONTENTS ABSTRACT ....................................................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................ iii TABLE OF CONTENTS ................................................................................................ iv LIST OF TABLES .......................................................................................................... vii LIST OF FIGURES ......................................................................................................... ix INTRODUCTION............................................................................................................. 1 RESEARCH TO DATE .......................................................................................................... 4 MUSIC AND CAPTIVE PRIMATE CARE ................................................................................. 6 ASSESSING PREFERENCE .................................................................................................... 7 Behavioural Observation During Stimulus Exposure .................................................. 7 The Least-Aversive or Most-Desired Choice Paradigm .............................................. 9 Participant-Controlled Procedures ............................................................................. 10 RATIONALE .................................................................................................................. 12 SPECIES OF INVESTIGATION ............................................................................................. 12 Orangutan Auditory Acuity ........................................................................................ 14 PURPOSE OF INVESTIGATION ........................................................................................... 15 METHOD ........................................................................................................................ 17 SUBJECTS . 17 DESIGN ............................................................................................................................ 17 Auditory Acuity Assessment ...................................................................................... 19 Study 1: Musical Preferences ..................................................................................... 22 Phase I: Music Preferences vs. Silence ................................................................. 22 Data Analysis ........................................................................................... 23 Phase II: Music-Silence Shuffle ............................................................................ 24 Data Analysis ........................................................................................... 25 Phase III: Musical Note Production ..................................................................... 25 Data Analysis ........................................................................................... 26 Study 2: Auditory Discrimination .............................................................................. 26 Phase I: Music vs. Scrambled Music .................................................................... 26 Data Analysis ........................................................................................... 28 Phase II: Male vs. Female Voices ......................................................................... 28 Data Analysis ........................................................................................... 29 RESULTS ........................................................................................................................ 30 iv AUDITORY ACUITY ASSESSMENT ................................................................................... 30 STUDY 1. MUSIC PREFERENCES ...................................................................................... 30 Phase I: Music Preferences vs. Silence ....................................................................... 30 Quantitative Analyses .......................................................................................... 30 Qualitative Analyses .......................................................................................... 32 Phase II: Music-Silence Shuffle ................................................................................. 33 Quantitative Analyses .......................................................................................... 33 Qualitative Analyses ........................................................................................... 3 3 Phase III: Musical Note Production ........................................................................... 35 Quantitative Analyses .......................................................................................... 35 Qualitative Analyses ........................................................................................... 35 STUDY 2: AUDITORY DISCRIMINATION ........................................................................... 35 Phase I: Music vs. Scrambled Music ......................................................................... 36 Quantitative Analyses .......................................................................................... 36 Qualitative Analyses ........................................................................................... 36 Phase II: Male vs. Female Voices .............................................................................. 38 Quantitative Analyses .......................................................................................... 38 Qualitative Analyses ........................................................................................... 39 DISCUSSION .................................................................................................................. 41 AUDITORY ACUITY ASSESSMENT ................................................................................... 41 STUDY 1: MUSIC PREFERENCES ...................................................................................... 42 Phase I: Music Preferences vs. Silence ...................................................................... 42 Phase II: Music-Silence Shuffle ................................................................................. 43 Phase III: Musical Note Production ..........................................................................