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Playful expressions of one-year-old chimpanzee infants in social and solitary play contexts.

Ross KM, Bard KA, Matsuzawa T - Front Psychol (2014)

Bottom Line: No group or age differences were found in the rate of infant playful expressions.Matched expression rates were highest when playing with peers despite infant expressiveness being highest when playing with older chimpanzees.Given that playful expressions emerge early in life and continue to occur in solitary contexts through the second year of life, we suggest that the play face and certain body behaviors are emotional expressions of joy, and that such expressions develop additional social functions through interactions with peers and older social partners.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Winchester Winchester, UK ; Department of Psychology, Centre for Comparative and Evolutionary Psychology, University of Portsmouth Portsmouth, UK.

ABSTRACT
Knowledge of the context and development of playful expressions in chimpanzees is limited because research has tended to focus on social play, on older subjects, and on the communicative signaling function of expressions. Here we explore the rate of playful facial and body expressions in solitary and social play, changes from 12- to 15-months of age, and the extent to which social partners match expressions, which may illuminate a route through which context influences expression. Naturalistic observations of seven chimpanzee infants (Pan troglodytes) were conducted at Chester Zoo, UK (n = 4), and Primate Research Institute, Japan (n = 3), and at two ages, 12 months and 15 months. No group or age differences were found in the rate of infant playful expressions. However, modalities of playful expression varied with type of play: in social play, the rate of play faces was high, whereas in solitary play, the rate of body expressions was high. Among the most frequent types of play, mild contact social play had the highest rates of play faces and multi-modal expressions (often play faces with hitting). Social partners matched both infant play faces and infant body expressions, but play faces were matched at a significantly higher rate that increased with age. Matched expression rates were highest when playing with peers despite infant expressiveness being highest when playing with older chimpanzees. Given that playful expressions emerge early in life and continue to occur in solitary contexts through the second year of life, we suggest that the play face and certain body behaviors are emotional expressions of joy, and that such expressions develop additional social functions through interactions with peers and older social partners.

No MeSH data available.


Related in: MedlinePlus

Mean rates (intervals per minute of play, with SE) of chimpanzee infants' playful expressions by modality (play face, body, multimodal) and by sub-types of social and solitary play. Simple contrasts in One-Way ANOVA were conducted to compare expression rate during mild contact social play with the other three sub-types of play, for each modality of expression. *p < 0.05, **p < 0.01, ***p < 0.001.
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Figure 4: Mean rates (intervals per minute of play, with SE) of chimpanzee infants' playful expressions by modality (play face, body, multimodal) and by sub-types of social and solitary play. Simple contrasts in One-Way ANOVA were conducted to compare expression rate during mild contact social play with the other three sub-types of play, for each modality of expression. *p < 0.05, **p < 0.01, ***p < 0.001.

Mentions: Four sub-types of play (solitary locomotor play, solitary object play, social mild contact play, and social locomotor play) occurred with sufficient frequency to allow expression rates to be calculated for all infants. Expression rate was examined by play sub-type and modality. The effect of play sub-type was significant (F = 30.82, df = 3, 18, p < 0.001, η2p = 0.84), the effect of modality was significant (F = 17.86, df = 1.10, 6.62, p < 0.01, η2p = 0.75), and the interaction between modality and play sub-type was also significant (F = 8.06, df = 2.30, 13.81, p < 0.01, η2p = 0.57) (Figure 4). To examine the interaction effect, expression rate was examined by play sub-type for each modality. Play face rate and multimodal rate differed significantly across the four play sub-types, while body rate did not differ (play face, F = 16.47, df = 3, 18, p < 0.001, η2p = 0.73; multimodal, F = 17.57, df = 3, 18, p < 0.001, η2p = 0.75; body, F = 2.16, df = 3, 18, p = 0.13, η2p = 0.27). Simple contrasts showed that play face rate and multimodal rate were significantly higher during mild contact play than during the other play sub-types. Play face with hitting accounted for 73% of multimodal expressions during mild contact social play.


Playful expressions of one-year-old chimpanzee infants in social and solitary play contexts.

Ross KM, Bard KA, Matsuzawa T - Front Psychol (2014)

Mean rates (intervals per minute of play, with SE) of chimpanzee infants' playful expressions by modality (play face, body, multimodal) and by sub-types of social and solitary play. Simple contrasts in One-Way ANOVA were conducted to compare expression rate during mild contact social play with the other three sub-types of play, for each modality of expression. *p < 0.05, **p < 0.01, ***p < 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109582&req=5

Figure 4: Mean rates (intervals per minute of play, with SE) of chimpanzee infants' playful expressions by modality (play face, body, multimodal) and by sub-types of social and solitary play. Simple contrasts in One-Way ANOVA were conducted to compare expression rate during mild contact social play with the other three sub-types of play, for each modality of expression. *p < 0.05, **p < 0.01, ***p < 0.001.
Mentions: Four sub-types of play (solitary locomotor play, solitary object play, social mild contact play, and social locomotor play) occurred with sufficient frequency to allow expression rates to be calculated for all infants. Expression rate was examined by play sub-type and modality. The effect of play sub-type was significant (F = 30.82, df = 3, 18, p < 0.001, η2p = 0.84), the effect of modality was significant (F = 17.86, df = 1.10, 6.62, p < 0.01, η2p = 0.75), and the interaction between modality and play sub-type was also significant (F = 8.06, df = 2.30, 13.81, p < 0.01, η2p = 0.57) (Figure 4). To examine the interaction effect, expression rate was examined by play sub-type for each modality. Play face rate and multimodal rate differed significantly across the four play sub-types, while body rate did not differ (play face, F = 16.47, df = 3, 18, p < 0.001, η2p = 0.73; multimodal, F = 17.57, df = 3, 18, p < 0.001, η2p = 0.75; body, F = 2.16, df = 3, 18, p = 0.13, η2p = 0.27). Simple contrasts showed that play face rate and multimodal rate were significantly higher during mild contact play than during the other play sub-types. Play face with hitting accounted for 73% of multimodal expressions during mild contact social play.

Bottom Line: No group or age differences were found in the rate of infant playful expressions.Matched expression rates were highest when playing with peers despite infant expressiveness being highest when playing with older chimpanzees.Given that playful expressions emerge early in life and continue to occur in solitary contexts through the second year of life, we suggest that the play face and certain body behaviors are emotional expressions of joy, and that such expressions develop additional social functions through interactions with peers and older social partners.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Winchester Winchester, UK ; Department of Psychology, Centre for Comparative and Evolutionary Psychology, University of Portsmouth Portsmouth, UK.

ABSTRACT
Knowledge of the context and development of playful expressions in chimpanzees is limited because research has tended to focus on social play, on older subjects, and on the communicative signaling function of expressions. Here we explore the rate of playful facial and body expressions in solitary and social play, changes from 12- to 15-months of age, and the extent to which social partners match expressions, which may illuminate a route through which context influences expression. Naturalistic observations of seven chimpanzee infants (Pan troglodytes) were conducted at Chester Zoo, UK (n = 4), and Primate Research Institute, Japan (n = 3), and at two ages, 12 months and 15 months. No group or age differences were found in the rate of infant playful expressions. However, modalities of playful expression varied with type of play: in social play, the rate of play faces was high, whereas in solitary play, the rate of body expressions was high. Among the most frequent types of play, mild contact social play had the highest rates of play faces and multi-modal expressions (often play faces with hitting). Social partners matched both infant play faces and infant body expressions, but play faces were matched at a significantly higher rate that increased with age. Matched expression rates were highest when playing with peers despite infant expressiveness being highest when playing with older chimpanzees. Given that playful expressions emerge early in life and continue to occur in solitary contexts through the second year of life, we suggest that the play face and certain body behaviors are emotional expressions of joy, and that such expressions develop additional social functions through interactions with peers and older social partners.

No MeSH data available.


Related in: MedlinePlus