Perceived differences between chimpanzee (Pan troglodytes) and human (Homo sapiens) facial expressions are related to emotional interpretation. (original) (raw)
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It has long been recognized that behavior evolves as do other traits and that it may have great impact on evolution. It tends to be conservative when survival and fast responding are at stake, and because of that, similar patterns can be found across populations or species, typical in their form and intensity, and often also typical in context and consequence. Such fixed stereotypic patterns that evolved to communicate are known as displays, and their phylogenies can virtually be traced. In this chapter, we contrast and discuss two coexisting trends in the study of the meaning and origins of human facial expression: one, with a tradition of exploring cross-cultural commonalities in the recognition of facial expression, that may indicate species-specific displays of emotion (prototypical facial expressions) and another that builds upon the growing evidence that such expressive prototypes are outnumbered by a diversity of facial compositions that, even in emotional situations, vary in relation to culture, context, group, maturation, and individual factors. We present behavioral studies that look at links between basic emotion and facial actions in both human and non-human primates and discuss the role of multiple factors in facial action production and interpretation.
Personality and Temperament in …, 2011
Independently, we created descriptive systems to characterize chimpanzee facial behavior, responding to a common need to have an objective, standardized coding system to ask questions about primate facial behaviors. Even with slightly different systems, we arrive at similar outcomes, with convergent conclusions about chimpanzee facial mobility. This convergence is a validation of the importance of the approach, and provides support for the future use of a facial action coding system for chimpanzees, ChimpFACS . Chimpanzees share many facial behaviors with those of humans. Therefore, processes and mechanisms that explain individual differences in facial activity can be compared with the use of a standardized systems such as ChimpFACS and FAC S . In this chapter we describe our independent methodological approaches, comparing how we arrived at our facial coding categories. We present some Action Descriptors (ADs) from Gaspar's initial studies, especially focusing on an ethogram of chimpanzee and bonobo facial behavior, based on studies conducted between 1997 and 2004 at three chimpanzee colonies (The Detroit Zoo; Cleveland Metroparks Zoo; and Burger's Zoo) and two bonobo colonies (The Columbus Zoo and Aquarium; The Milwaukee County Zoo). We discuss the potential signifi cance of arising issues, the minor qualitative species differences that were found and the larger quantitative differences in particular facial behaviors observed between species, e.g., bonobos expressed more movements containing particular action units (Brow Lowerer, Lip Raiser, Lip Corner Puller) compared with chimpanzees. The substantial interindividual variation in facial behavior within each species was most striking. Considering individual differences and the impact of development, we highlight the fl exibility in facial activity of chimpanzees. We discuss the meaning of facial behaviors in nonhuman primates, addressing specifi cally n c o r r e c t e d P r o o f K.A. Bard et al. individual attributes of Social Attraction, facial expressivity, and the connection of facial behavior to emotion. We do not rule out the communicative function of facial behavior, in which case an individual's properties of facial behavior are seen as infl uencing his or her social life, but provide strong arguments in support of the role of facial behavior in the expression of internal states.
New Developments in Understanding Emotional Facial Signals in Chimpanzees
Current Directions in Psychological Science, 2007
There has been little research over the past few decades focusing on similarities and differences in the form and function of emotional signals in nonhuman primates, or whether these communication systems are homologous with those of humans. This is, in part, due to the fact that detailed and objective measurement tools to answer such questions have not been systematically developed for nonhuman primate research. Despite this, emotion research in humans has benefited for over 30 years from an objective, anatomically based facial-measurement tool: the Facial Action Coding System. In collaboration with other researchers, we have now developed a similar system for chimpanzees (ChimpFACS) and, in the process, have made exciting new discoveries regarding chimpanzees' perception and categorization of emotional facial expressions, similarities in the facial anatomy of chimpanzees and humans, and we have identified homologous facial movements in the two species. Investigating similarities and differences in primate emotional communication systems is essential if we are to understand unique evolutionary specializations among different species.
Personality and temperament in nonhuman …, 2011
Independently, we created descriptive systems to characterize chimpanzee facial behavior, responding to a common need to have an objective, standardized coding system to ask questions about primate facial behaviors. Even with slightly different systems, we arrive at similar outcomes, with convergent conclusions about chimpanzee facial mobility. This convergence is a validation of the importance of the approach, and provides support for the future use of a facial action coding system for chimpanzees, ChimpFACS . Chimpanzees share many facial behaviors with those of humans. Therefore, processes and mechanisms that explain individual differences in facial activity can be compared with the use of a standardized systems such as ChimpFACS and FAC S . In this chapter we describe our independent methodological approaches, comparing how we arrived at our facial coding categories. We present some Action Descriptors (ADs) from Gaspar's initial studies, especially focusing on an ethogram of chimpanzee and bonobo facial behavior, based on studies conducted between 1997 and 2004 at three chimpanzee colonies (The Detroit Zoo; Cleveland Metroparks Zoo; and Burger's Zoo) and two bonobo colonies (The Columbus Zoo and Aquarium; The Milwaukee County Zoo). We discuss the potential signifi cance of arising issues, the minor qualitative species differences that were found and the larger quantitative differences in particular facial behaviors observed between species, e.g., bonobos expressed more movements containing particular action units (Brow Lowerer, Lip Raiser, Lip Corner Puller) compared with chimpanzees. The substantial interindividual variation in facial behavior within each species was most striking. Considering individual differences and the impact of development, we highlight the fl exibility in facial activity of chimpanzees. We discuss the meaning of facial behaviors in nonhuman primates, addressing specifi cally n c o r r e c t e d P r o o f K.A. Bard et al. individual attributes of Social Attraction, facial expressivity, and the connection of facial behavior to emotion. We do not rule out the communicative function of facial behavior, in which case an individual's properties of facial behavior are seen as infl uencing his or her social life, but provide strong arguments in support of the role of facial behavior in the expression of internal states.
It has long been recognized that behavior evolves as do other traits and that it may have great impact on evolution. It tends to be conservative when survival and fast responding are at stake, and because of that, similar patterns can be found across populations or species, typical in their form and intensity, and often also typical in context and consequence. Such fixed stereotypic patterns that evolved to communicate are known as displays, and their phylogenies can virtually be traced. In this chapter, we contrast and discuss two coexisting trends in the study of the meaning and origins of human facial expression: one, with a tradition of exploring cross-cultural commonalities in the recognition of facial expression, that may indicate species-specific displays of emotion (prototypical facial expressions) and another that builds upon the growing evidence that such expressive prototypes are outnumbered by a diversity of facial compositions that, even in emotional situations, vary in relation to culture, context, group, maturation, and individual factors. We present behavioral studies that look at links between basic emotion and facial actions in both human and non-human primates and discuss the role of multiple factors in facial action production and interpretation.
Viewing heterospecific facial expressions: an eye-tracking study of human and monkey viewers
Experimental Brain Research, 2019
Common facial expressions of emotion have distinctive patterns of facial muscle movements that are culturally similar among humans, and perceiving these expressions is associated with stereotypical gaze allocation at local facial regions that are characteristic for each expression, such as eyes in angry faces. It is, however, unclear to what extent this 'universality' view can be extended to process heterospecific facial expressions, and how 'social learning' process contributes to heterospecific expression perception. In this eye-tracking study, we examined face-viewing gaze allocation of human (including dog owners and non-dog owners) and monkey observers while exploring expressive human, chimpanzee, monkey and dog faces (positive, neutral and negative expressions in human and dog faces; neutral and negative expressions in chimpanzee and monkey faces). Human observers showed species-and experience-dependent expression categorization accuracy. Furthermore, both human and monkey observers demonstrated different face-viewing gaze distributions which were also species dependent. Specifically, humans predominately attended at human eyes but animal mouth when judging facial expressions. Monkeys' gaze distributions in exploring human and monkey faces were qualitatively different from exploring chimpanzee and dog faces. Interestingly, the gaze behaviour of both human and monkey observers were further affected by their prior experience of the viewed species. It seems that facial expression processing is species dependent, and social learning may play a significant role in discriminating even rudimentary types of heterospecific expressions.
Journal of Nonverbal …, 2007
A comparative perspective has remained central to the study of human facial expressions since . The expression of the emotions in man and animals (3rd ed.). New York: Oxford University Press] insightful observations on the presence and significance of cross-species continuities and species-unique phenomena. However, cross-species comparisons are often difficult to draw due to methodological limitations. We report the application of a common methodology, the Facial Action Coding System (FACS) to examine facial movement across two species of hominoids, namely humans and chimpanzees. FACS . Facial action coding system. CA: Consulting Psychology Press] has been employed to identify the repertoire of human facial movements. We demonstrate that FACS can be applied to other species, but highlight that any modifications must be based on both underlying anatomy and detailed observational analysis of movements. Here we describe the ChimpFACS and use it to compare the repertoire of facial movement in chimpanzees and humans. While the underlying mimetic musculature shows minimal differences, important differences in facial morphology impact upon the identification and detection of related surface appearance changes across these two species.
Classifying Chimpanzee Facial Expressions Using Muscle Action
Emotion, 2007
The Chimpanzee Facial Action Coding System (ChimpFACS) is an objective, standardized observational tool for measuring facial movement in chimpanzees based on the well-known human Facial Action Coding System (FACS; P. Ekman & W. V. Friesen, 1978). This tool enables direct structural comparisons of facial expressions between humans and chimpanzees in terms of their common underlying musculature. Here the authors provide data on the first application of the ChimpFACS to validate existing categories of chimpanzee facial expressions using discriminant functions analyses. The ChimpFACS validated most existing expression categories (6 of 9) and, where the predicted group memberships were poor, the authors discuss potential problems with ChimpFACS and/or existing categorizations. The authors also report the prototypical movement configurations associated with these 6 expression categories. For all expressions, unique combinations of muscle movements were identified, and these are illustrated as peak intensity prototypical expression configurations. Finally, the authors suggest a potential homology between these prototypical chimpanzee expressions and human expressions based on structural similarities. These results contribute to our understanding of the evolution of emotional communication by suggesting several structural homologies between the facial expressions of chimpanzees and humans and facilitating future research.
The Emotional Expressions and Emotion Perception in Nonhuman Primates
2022
The expression of emotions and their recognition in conspecifics are pivotal to social life. As Darwin postulated in his pioneering book The expression of the emotions in man and animals, many morphological features and functions of emotional expressions character ized in humans are homologous to those of other animals. Intriguingly, despite this early work, scientists have been skeptical about the feasibility of studying emotions in nonhu mans and, therefore, the study of their emotional expressions has been limited. However, recent technological advances in neuroscience, genetics, and fine-scale behavioral analy ses enable researchers to investigate human emotions in direct comparison with other an imals. Throughout this chapter, the authors provide convincing evidence that nonhuman primates produce and recognize conspecific emotional expressions. Some of them, espe cially the bared-teeth display, are used in multiple contexts, suggesting cognitively so phisticated functions. The flexible use of emotional expressions seems to be tightly linked to species sociality, such as level of tolerance.