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Roth TS, Samara I, Perea-Garcia JO, Kret ME. No immediate attentional bias towards or choice bias for male secondary sexual characteristics in Bornean orang-utans (Pongo pygmaeus). Sci Rep 2024; 14:12095. [PMID: 38802458 PMCID: PMC11130206 DOI: 10.1038/s41598-024-62187-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 05/14/2024] [Indexed: 05/29/2024] Open
Abstract
Primate faces provide information about a range of variant and invariant traits, including some that are relevant for mate choice. For example, faces of males may convey information about their health or genetic quality through symmetry or facial masculinity. Because perceiving and processing such information may have bearing on the reproductive success of an individual, cognitive systems are expected to be sensitive to facial cues of mate quality. However, few studies have investigated this topic in non-human primate species. Orang-utans are an interesting species to test mate-relevant cognitive biases, because they are characterised by male bimaturism: some adult males are fully developed and bear conspicuous flanges on the side of their face, while other males look relatively similar to females. Here, we describe two non-invasive computerised experiments with Bornean orang-utans (Pongo pygmaeus), testing (i) immediate attention towards large flanges and symmetrical faces using a dot-probe task (N = 3 individuals; 2F) and (ii) choice bias for pictures of flanged males over unflanged males using a preference test (N = 6 individuals; 4F). In contrast with our expectations, we found no immediate attentional bias towards either large flanges or symmetrical faces. In addition, individuals did not show a choice bias for stimuli of flanged males. We did find exploratory evidence for a colour bias and energy efficiency trade-offs in the preference task. We discuss our null results and exploratory results in the context of the evolutionary history of Bornean orang-utans, and provide suggestions for a more biocentric approach to the study of orang-utan cognition.
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Affiliation(s)
- Tom S Roth
- Cognitive Psychology Unit, Institute of Psychology, The Faculty of Social and Behavioral Sciences, Leiden University, Wassenaarseweg 52, 2333 AK, Leiden, The Netherlands.
- Apenheul Primate Park, J.CWilslaan 21, 7313 HK, Apeldoorn, The Netherlands.
- Animal Behaviour & Cognition, Department of Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
| | - Iliana Samara
- Cognitive Psychology Unit, Institute of Psychology, The Faculty of Social and Behavioral Sciences, Leiden University, Wassenaarseweg 52, 2333 AK, Leiden, The Netherlands
- Leiden Institute of Brain and Cognition (LIBC), Leiden, The Netherlands
| | - Juan Olvido Perea-Garcia
- Cognitive Psychology Unit, Institute of Psychology, The Faculty of Social and Behavioral Sciences, Leiden University, Wassenaarseweg 52, 2333 AK, Leiden, The Netherlands
| | - Mariska E Kret
- Cognitive Psychology Unit, Institute of Psychology, The Faculty of Social and Behavioral Sciences, Leiden University, Wassenaarseweg 52, 2333 AK, Leiden, The Netherlands
- Leiden Institute of Brain and Cognition (LIBC), Leiden, The Netherlands
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Wilson VAD, Masilkova M. Does the primate face cue personality? PERSONALITY NEUROSCIENCE 2023; 6:e7. [PMID: 38107779 PMCID: PMC10725780 DOI: 10.1017/pen.2023.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/24/2023] [Accepted: 05/31/2023] [Indexed: 12/19/2023]
Abstract
When looking at others, primates primarily focus on the face - detecting the face first and looking at it longer than other parts of the body. This is because primate faces, even without expression, convey trait information crucial for navigating social relationships. Recent studies on primates, including humans, have linked facial features, specifically facial width-to-height ratio (fWHR), to rank and Dominance-related personality traits, suggesting these links' potential role in social decisions. However, studies on the association between dominance and fWHR report contradictory results in humans and variable patterns in nonhuman primates. It is also not clear whether and how nonhuman primates perceive different facial cues to personality traits and whether these may have evolved as social signals. This review summarises the variable facial-personality links, their underlying proximate and evolutionary mechanisms and their perception across primates. We emphasise the importance of employing comparative research, including various primate species and human populations, to disentangle phylogeny from socio-ecological drivers and to understand the selection pressures driving the facial-personality links in humans. Finally, we encourage researchers to move away from single facial measures and towards holistic measures and to complement perception studies using neuroscientific methods.
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Affiliation(s)
- Vanessa A D Wilson
- Department of Comparative Cognition, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Department of Comparative Language Science, University of Zurich, Zurich, Switzerland
- Center for the Interdisciplinary Study of Language Evolution (ISLE), University of Zurich, Zurich, Switzerland
| | - Michaela Masilkova
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic
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Wilson VAD, Bethell EJ, Nawroth C. The use of gaze to study cognition: limitations, solutions, and applications to animal welfare. Front Psychol 2023; 14:1147278. [PMID: 37205074 PMCID: PMC10185774 DOI: 10.3389/fpsyg.2023.1147278] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/17/2023] [Indexed: 05/21/2023] Open
Abstract
The study of gaze responses, typically using looking time paradigms, has become a popular approach to improving our understanding of cognitive processes in non-verbal individuals. Our interpretation of data derived from these paradigms, however, is constrained by how we conceptually and methodologically approach these problems. In this perspective paper, we outline the application of gaze studies in comparative cognitive and behavioral research and highlight current limitations in the interpretation of commonly used paradigms. Further, we propose potential solutions, including improvements to current experimental approaches, as well as broad-scale benefits of technology and collaboration. Finally, we outline the potential benefits of studying gaze responses from an animal welfare perspective. We advocate the implementation of these proposals across the field of animal behavior and cognition to aid experimental validity, and further advance our knowledge on a variety of cognitive processes and welfare outcomes.
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Affiliation(s)
- Vanessa A. D. Wilson
- Department of Comparative Cognition, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Department of Comparative Language Science, University of Zurich, Zurich, Switzerland
- Center for the Interdisciplinary Study of Language Evolution (ISLE), University of Zurich, Zurich, Switzerland
- *Correspondence: Vanessa A. D. Wilson,
| | - Emily J. Bethell
- Research Centre in Evolutionary Anthropology and Palaeoecology, Liverpool John Moores University, Liverpool, United Kingdom
| | - Christian Nawroth
- Institute of Behavioural Physiology, Research Institute for Farm Animal Biology (FBN), Dummerstorf, Germany
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4
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Monkey visual attention does not fall into the uncanny valley. Sci Rep 2022; 12:11760. [PMID: 35817791 PMCID: PMC9273626 DOI: 10.1038/s41598-022-14615-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 06/09/2022] [Indexed: 11/08/2022] Open
Abstract
Very humanlike artificial agents can induce feelings of uneasiness in human perceivers. Stimuli that generate this response are said to occupy "the uncanny valley". Given inconsistent findings in the literature, whether or not nonhuman animals experience the uncanny valley is unclear. Here, we recorded the visual attention of eleven male rhesus monkeys as they viewed faces varying in realness across five levels, with visual attention measured by both number and duration of visual fixations on faces as a whole and on areas of interest within the faces (e.g., eyes, mouth). Face stimuli varied in terms of the realism of the image and behavior depicted by the face (lipsmack, threat, bared teeth, and neutral). We largely found no support that rhesus monkeys perceive an uncanny valley when viewing our stimuli; however, monkeys did generally pay more attention to eyes and less attention to mouths in real images compared to less realistic images. Across all stimuli, monkeys' visual attention was drawn to the mouths of images when teeth were visible. These findings suggest that rhesus monkeys in our study did not display an uncanny valley effect when viewing realistic stimuli but did percieve affective information depicted by faces regardless of how real those faces appear.
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Abstract
In order to understand ecologically meaningful social behaviors and their neural substrates in humans and other animals, researchers have been using a variety of social stimuli in the laboratory with a goal of extracting specific processes in real-life scenarios. However, certain stimuli may not be sufficiently effective at evoking typical social behaviors and neural responses. Here, we review empirical research employing different types of social stimuli by classifying them into five levels of naturalism. We describe the advantages and limitations while providing selected example studies for each level. We emphasize the important trade-off between experimental control and ecological validity across the five levels of naturalism. Taking advantage of newly emerging tools, such as real-time videos, virtual avatars, and wireless neural sampling techniques, researchers are now more than ever able to adopt social stimuli at a higher level of naturalism to better capture the dynamics and contingency of real-life social interaction.
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Affiliation(s)
- Siqi Fan
- Department of Psychology, Yale University, New Haven, CT 06520, USA
| | - Olga Dal Monte
- Department of Psychology, Yale University, New Haven, CT 06520, USA
- Department of Psychology, University of Turin, Torino, Italy
| | - Steve W.C. Chang
- Department of Psychology, Yale University, New Haven, CT 06520, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06510, USA
- Wu Tsai Institute, Yale University, New Haven, CT 06510, USA
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Taubert N, Stettler M, Siebert R, Spadacenta S, Sting L, Dicke P, Thier P, Giese MA. Shape-invariant encoding of dynamic primate facial expressions in human perception. eLife 2021; 10:61197. [PMID: 34115584 PMCID: PMC8195610 DOI: 10.7554/elife.61197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 04/22/2021] [Indexed: 11/30/2022] Open
Abstract
Dynamic facial expressions are crucial for communication in primates. Due to the difficulty to control shape and dynamics of facial expressions across species, it is unknown how species-specific facial expressions are perceptually encoded and interact with the representation of facial shape. While popular neural network models predict a joint encoding of facial shape and dynamics, the neuromuscular control of faces evolved more slowly than facial shape, suggesting a separate encoding. To investigate these alternative hypotheses, we developed photo-realistic human and monkey heads that were animated with motion capture data from monkeys and humans. Exact control of expression dynamics was accomplished by a Bayesian machine-learning technique. Consistent with our hypothesis, we found that human observers learned cross-species expressions very quickly, where face dynamics was represented largely independently of facial shape. This result supports the co-evolution of the visual processing and motor control of facial expressions, while it challenges appearance-based neural network theories of dynamic expression recognition.
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Affiliation(s)
- Nick Taubert
- Section for Computational Sensomotorics, Centre for Integrative Neuroscience & Hertie Institute for Clinical Brain Research, University Clinic Tübingen, Tübingen, Germany
| | - Michael Stettler
- Section for Computational Sensomotorics, Centre for Integrative Neuroscience & Hertie Institute for Clinical Brain Research, University Clinic Tübingen, Tübingen, Germany.,International Max Planck Research School for Intelligent Systems (IMPRS-IS), Tübingen, Germany
| | - Ramona Siebert
- Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Silvia Spadacenta
- Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Louisa Sting
- Section for Computational Sensomotorics, Centre for Integrative Neuroscience & Hertie Institute for Clinical Brain Research, University Clinic Tübingen, Tübingen, Germany
| | - Peter Dicke
- Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Peter Thier
- Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Martin A Giese
- Section for Computational Sensomotorics, Centre for Integrative Neuroscience & Hertie Institute for Clinical Brain Research, University Clinic Tübingen, Tübingen, Germany
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van Berlo E, Díaz-Loyo AP, Juárez-Mora OE, Kret ME, Massen JJM. Experimental evidence for yawn contagion in orangutans (Pongo pygmaeus). Sci Rep 2020; 10:22251. [PMID: 33335177 PMCID: PMC7747555 DOI: 10.1038/s41598-020-79160-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 12/03/2020] [Indexed: 11/17/2022] Open
Abstract
Yawning is highly contagious, yet both its proximate mechanism(s) and its ultimate causation remain poorly understood. Scholars have suggested a link between contagious yawning (CY) and sociality due to its appearance in mostly social species. Nevertheless, as findings are inconsistent, CY’s function and evolution remains heavily debated. One way to understand the evolution of CY is by studying it in hominids. Although CY has been found in chimpanzees and bonobos, but is absent in gorillas, data on orangutans are missing despite them being the least social hominid. Orangutans are thus interesting for understanding CY’s phylogeny. Here, we experimentally tested whether orangutans yawn contagiously in response to videos of conspecifics yawning. Furthermore, we investigated whether CY was affected by familiarity with the yawning individual (i.e. a familiar or unfamiliar conspecific and a 3D orangutan avatar). In 700 trials across 8 individuals, we found that orangutans are more likely to yawn in response to yawn videos compared to control videos of conspecifics, but not to yawn videos of the avatar. Interestingly, CY occurred regardless of whether a conspecific was familiar or unfamiliar. We conclude that CY was likely already present in the last common ancestor of humans and great apes, though more converging evidence is needed.
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Affiliation(s)
- Evy van Berlo
- Institute of Psychology, Cognitive Psychology Unit, Leiden University, Leiden, The Netherlands. .,Leiden Institute for Brain and Cognition (LIBC), Leiden, The Netherlands.
| | - Alejandra P Díaz-Loyo
- Laboratorio de Ecología de La Conducta, Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Oscar E Juárez-Mora
- Laboratorio de Ecología de La Conducta, Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Mariska E Kret
- Institute of Psychology, Cognitive Psychology Unit, Leiden University, Leiden, The Netherlands.,Leiden Institute for Brain and Cognition (LIBC), Leiden, The Netherlands
| | - Jorg J M Massen
- Department of Biology, Animal Ecology Group, Utrecht University, Utrecht, The Netherlands
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