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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 multimodal expressions during social and solitary play contexts. PF, play face. *p < 0.05, **p < 0.01.
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Figure 3: Mean rates (intervals per minute of play, with SE) of chimpanzee infants' playful multimodal expressions during social and solitary play contexts. PF, play face. *p < 0.05, **p < 0.01.

Mentions: Multimodal expressions were subdivided into five types: play face with hitting (48%), play face with flailing limbs (20%), play face with tickle request (13%), play face with acrobatics (12%), and play face with bouncing (6%). Expression rate was examined by multimodal type and play context. Rates differed significantly by multimodal type (F = 7.37, df = 4, 24, p < 0.001, η2p = 0.55), and there was a significant interaction between multimodal type and play context (F = 6.01, df = 4, 24, p < 0.01, η2p = 0.50) (Figure 3). Pairwise comparisons (Bonferroni adjusted) showed that the rate of play face with hitting was significantly higher than the rate of play face with flailing limbs (mean difference = 0.179, p < 0.05). The multimodal type × play type interaction was examined by comparing the expression rate by multimodal type across social and solitary play. One type of expression, play face with hitting, was displayed at a significantly higher rate during social play than during solitary play (F = 16.57, df = 1, 6, p < 0.01, η2p = 0.73), and none of the other types of multimodal expression differed significantly by play context. Note that although play face with tickle request expressions were observed only during social play, three infants never displayed this multimodal expression. Only two types of multimodal expressions occurred at rates significantly higher than 0: play face with hitting during social play (t = 4.28, p < 0.01) and play face with acrobatics during solitary play (t = 3.485, p < 0.05).


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 multimodal expressions during social and solitary play contexts. PF, play face. *p < 0.05, **p < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Mean rates (intervals per minute of play, with SE) of chimpanzee infants' playful multimodal expressions during social and solitary play contexts. PF, play face. *p < 0.05, **p < 0.01.
Mentions: Multimodal expressions were subdivided into five types: play face with hitting (48%), play face with flailing limbs (20%), play face with tickle request (13%), play face with acrobatics (12%), and play face with bouncing (6%). Expression rate was examined by multimodal type and play context. Rates differed significantly by multimodal type (F = 7.37, df = 4, 24, p < 0.001, η2p = 0.55), and there was a significant interaction between multimodal type and play context (F = 6.01, df = 4, 24, p < 0.01, η2p = 0.50) (Figure 3). Pairwise comparisons (Bonferroni adjusted) showed that the rate of play face with hitting was significantly higher than the rate of play face with flailing limbs (mean difference = 0.179, p < 0.05). The multimodal type × play type interaction was examined by comparing the expression rate by multimodal type across social and solitary play. One type of expression, play face with hitting, was displayed at a significantly higher rate during social play than during solitary play (F = 16.57, df = 1, 6, p < 0.01, η2p = 0.73), and none of the other types of multimodal expression differed significantly by play context. Note that although play face with tickle request expressions were observed only during social play, three infants never displayed this multimodal expression. Only two types of multimodal expressions occurred at rates significantly higher than 0: play face with hitting during social play (t = 4.28, p < 0.01) and play face with acrobatics during solitary play (t = 3.485, p < 0.05).

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