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Visual recognition of age class and preference for infantile features: implications for species-specific vs universal cognitive traits in primates.

Sato A, Koda H, Lemasson A, Nagumo S, Masataka N - PLoS ONE (2012)

Bottom Line: When analyzing the side of the first look, JM subjects significantly looked more often at novel images.CM subjects showed no difference in the side of their first look, but looked at infant JM images longer than they looked at adult images; the fact that CMs were totally naïve to JMs suggested that the attractiveness of infant images transcends species differences.Our results suggest not only species-specific processing for age class recognition but also the evolutionary origins of the instinctive human perception of baby cuteness schema, proposed by the ethologist Konrad Lorenz.

View Article: PubMed Central - PubMed

Affiliation: Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan.

ABSTRACT
Despite not knowing the exact age of individuals, humans can estimate their rough age using age-related physical features. Nonhuman primates show some age-related physical features; however, the cognitive traits underlying their recognition of age class have not been revealed. Here, we tested the ability of two species of Old World monkey, Japanese macaques (JM) and Campbell's monkeys (CM), to spontaneously discriminate age classes using visual paired comparison (VPC) tasks based on the two distinct categories of infant and adult images. First, VPCs were conducted in JM subjects using conspecific JM stimuli. When analyzing the side of the first look, JM subjects significantly looked more often at novel images. Based on analyses of total looking durations, JM subjects looked at a novel infant image longer than they looked at a familiar adult image, suggesting the ability to spontaneously discriminate between the two age classes and a preference for infant over adult images. Next, VPCs were tested in CM subjects using heterospecific JM stimuli. CM subjects showed no difference in the side of their first look, but looked at infant JM images longer than they looked at adult images; the fact that CMs were totally naïve to JMs suggested that the attractiveness of infant images transcends species differences. This is the first report of visual age class recognition and a preference for infant over adult images in nonhuman primates. Our results suggest not only species-specific processing for age class recognition but also the evolutionary origins of the instinctive human perception of baby cuteness schema, proposed by the ethologist Konrad Lorenz.

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First look sides (FLs) for the stimulus novelty and order conditions in 44 trials of 11 Japanese macaque subjects.In the adult/infant (AI) condition, the adult image was used as the stimulus in the familiar phase and the infant image served as the novel stimulus in the test phase. In the infant/adult (IA) condition, the infant image was used as the stimulus in the familiar phase and the adult imaged served as the novel stimulus in the test phase. Black bars, FLs for familiar stimuli; white bars, FLs for novel stimuli.
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pone-0038387-g002: First look sides (FLs) for the stimulus novelty and order conditions in 44 trials of 11 Japanese macaque subjects.In the adult/infant (AI) condition, the adult image was used as the stimulus in the familiar phase and the infant image served as the novel stimulus in the test phase. In the infant/adult (IA) condition, the infant image was used as the stimulus in the familiar phase and the adult imaged served as the novel stimulus in the test phase. Black bars, FLs for familiar stimuli; white bars, FLs for novel stimuli.

Mentions: Figure 2 shows the side of the first look (FL) in the two order conditions in Experiment 1. The GLMM analysis revealed no significant main effect for order condition (Estimated parameter coeffiencet ± se, 0.22±0.66, z = 0.33, P = 0.74), suggesting that FL patterns were equivalent between AI and IA conditions. Further analysis for intercept of GLMM showed that the probability of FL for novel images were higher than those for familiar ones (Intercept, 0.89±0.33, z = 2.63, P = 0.0085), suggesting that JM subjects looked first at novel images regardless of order conditions. Figure 3 shows the total look durations (LT) for the novel and the familiar stimuli in the two order conditions in Experiment 1. The GLMM analysis revealed a significant main effect for novelty (F1,42 = 8.16, P = 0.0066) but no significant effect for order condition (F1,32 = 1.30, P = 0.262); however, an interaction effect was found between novelty category and order condition (F1,42 = 6.41, P = 0.0152). This finding suggests that the effect of novelty (LT differences between novel and familiar stimuli) differed between the AI and IA conditions. The analysis of parameter coefficients in the GLMM revealed that the LT for novel images was significantly longer than that for familiar images in the AI condition, whereas no effect of novelty was found in the IA condition (Figure 3, Table 1). This finding indicates that LT for the novel stimulus was significantly longer than that for the familiar stimulus only when the novel stimulus was the infant image. Thus, JMs looked at infant images for a significantly longer time than they looked at adult images. These results demonstrate that JM subjects possess a spontaneous ability to discriminate infant images from adult images. Furthermore, JM subjects preferred looking at infant images over adult images.


Visual recognition of age class and preference for infantile features: implications for species-specific vs universal cognitive traits in primates.

Sato A, Koda H, Lemasson A, Nagumo S, Masataka N - PLoS ONE (2012)

First look sides (FLs) for the stimulus novelty and order conditions in 44 trials of 11 Japanese macaque subjects.In the adult/infant (AI) condition, the adult image was used as the stimulus in the familiar phase and the infant image served as the novel stimulus in the test phase. In the infant/adult (IA) condition, the infant image was used as the stimulus in the familiar phase and the adult imaged served as the novel stimulus in the test phase. Black bars, FLs for familiar stimuli; white bars, FLs for novel stimuli.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368701&req=5

pone-0038387-g002: First look sides (FLs) for the stimulus novelty and order conditions in 44 trials of 11 Japanese macaque subjects.In the adult/infant (AI) condition, the adult image was used as the stimulus in the familiar phase and the infant image served as the novel stimulus in the test phase. In the infant/adult (IA) condition, the infant image was used as the stimulus in the familiar phase and the adult imaged served as the novel stimulus in the test phase. Black bars, FLs for familiar stimuli; white bars, FLs for novel stimuli.
Mentions: Figure 2 shows the side of the first look (FL) in the two order conditions in Experiment 1. The GLMM analysis revealed no significant main effect for order condition (Estimated parameter coeffiencet ± se, 0.22±0.66, z = 0.33, P = 0.74), suggesting that FL patterns were equivalent between AI and IA conditions. Further analysis for intercept of GLMM showed that the probability of FL for novel images were higher than those for familiar ones (Intercept, 0.89±0.33, z = 2.63, P = 0.0085), suggesting that JM subjects looked first at novel images regardless of order conditions. Figure 3 shows the total look durations (LT) for the novel and the familiar stimuli in the two order conditions in Experiment 1. The GLMM analysis revealed a significant main effect for novelty (F1,42 = 8.16, P = 0.0066) but no significant effect for order condition (F1,32 = 1.30, P = 0.262); however, an interaction effect was found between novelty category and order condition (F1,42 = 6.41, P = 0.0152). This finding suggests that the effect of novelty (LT differences between novel and familiar stimuli) differed between the AI and IA conditions. The analysis of parameter coefficients in the GLMM revealed that the LT for novel images was significantly longer than that for familiar images in the AI condition, whereas no effect of novelty was found in the IA condition (Figure 3, Table 1). This finding indicates that LT for the novel stimulus was significantly longer than that for the familiar stimulus only when the novel stimulus was the infant image. Thus, JMs looked at infant images for a significantly longer time than they looked at adult images. These results demonstrate that JM subjects possess a spontaneous ability to discriminate infant images from adult images. Furthermore, JM subjects preferred looking at infant images over adult images.

Bottom Line: When analyzing the side of the first look, JM subjects significantly looked more often at novel images.CM subjects showed no difference in the side of their first look, but looked at infant JM images longer than they looked at adult images; the fact that CMs were totally naïve to JMs suggested that the attractiveness of infant images transcends species differences.Our results suggest not only species-specific processing for age class recognition but also the evolutionary origins of the instinctive human perception of baby cuteness schema, proposed by the ethologist Konrad Lorenz.

View Article: PubMed Central - PubMed

Affiliation: Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan.

ABSTRACT
Despite not knowing the exact age of individuals, humans can estimate their rough age using age-related physical features. Nonhuman primates show some age-related physical features; however, the cognitive traits underlying their recognition of age class have not been revealed. Here, we tested the ability of two species of Old World monkey, Japanese macaques (JM) and Campbell's monkeys (CM), to spontaneously discriminate age classes using visual paired comparison (VPC) tasks based on the two distinct categories of infant and adult images. First, VPCs were conducted in JM subjects using conspecific JM stimuli. When analyzing the side of the first look, JM subjects significantly looked more often at novel images. Based on analyses of total looking durations, JM subjects looked at a novel infant image longer than they looked at a familiar adult image, suggesting the ability to spontaneously discriminate between the two age classes and a preference for infant over adult images. Next, VPCs were tested in CM subjects using heterospecific JM stimuli. CM subjects showed no difference in the side of their first look, but looked at infant JM images longer than they looked at adult images; the fact that CMs were totally naïve to JMs suggested that the attractiveness of infant images transcends species differences. This is the first report of visual age class recognition and a preference for infant over adult images in nonhuman primates. Our results suggest not only species-specific processing for age class recognition but also the evolutionary origins of the instinctive human perception of baby cuteness schema, proposed by the ethologist Konrad Lorenz.

Show MeSH
Related in: MedlinePlus