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Being Barbie: the size of one's own body determines the perceived size of the world.

van der Hoort B, Guterstam A, Ehrsson HH - PLoS ONE (2011)

Bottom Line: These effects were quantified in ten separate experiments with complementary verbal, questionnaire, manual, walking, and physiological measures.Importantly, despite identical retinal input, this "body size effect" was greater when the participants experienced a sense of ownership of the artificial bodies compared to a control condition in which ownership was disrupted.Thus, our own body size affects how we perceive the world.

View Article: PubMed Central - PubMed

Affiliation: Brain, Body and Self Laboratory, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden. bvdhoort@gmail.com

ABSTRACT
A classical question in philosophy and psychology is if the sense of one's body influences how one visually perceives the world. Several theoreticians have suggested that our own body serves as a fundamental reference in visual perception of sizes and distances, although compelling experimental evidence for this hypothesis is lacking. In contrast, modern textbooks typically explain the perception of object size and distance by the combination of information from different visual cues. Here, we describe full body illusions in which subjects experience the ownership of a doll's body (80 cm or 30 cm) and a giant's body (400 cm) and use these as tools to demonstrate that the size of one's sensed own body directly influences the perception of object size and distance. These effects were quantified in ten separate experiments with complementary verbal, questionnaire, manual, walking, and physiological measures. When participants experienced the tiny body as their own, they perceived objects to be larger and farther away, and when they experienced the large-body illusion, they perceived objects to be smaller and nearer. Importantly, despite identical retinal input, this "body size effect" was greater when the participants experienced a sense of ownership of the artificial bodies compared to a control condition in which ownership was disrupted. These findings are fundamentally important as they suggest a causal relationship between the representations of body space and external space. Thus, our own body size affects how we perceive the world.

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Related in: MedlinePlus

Results of Experiments 6–8: Own body size effect on size perception.The body size effect on verbal size estimation (A) and hand aperture (B) as a percentage deviation from the average estimation of all trials and the effect of the ownership illusion on hand aperture as a percentage deviation from corresponding asynchronous condition (C). * p<0.05, ** p<0.01, *** p<0.001. Error bars indicate SEM.
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pone-0020195-g004: Results of Experiments 6–8: Own body size effect on size perception.The body size effect on verbal size estimation (A) and hand aperture (B) as a percentage deviation from the average estimation of all trials and the effect of the ownership illusion on hand aperture as a percentage deviation from corresponding asynchronous condition (C). * p<0.05, ** p<0.01, *** p<0.001. Error bars indicate SEM.

Mentions: Compared with the illusion of owning a normal-sized artificial body, participants gave significantly higher verbal estimates of cube size during the small-body illusion (n = 14, Z = 2.982, p<0.005; Wilcoxon signed-rank test) and significantly lower estimates when experiencing the large-body illusion (n = 14, Z = −1.713, p<0.05; Wilcoxon signed-rank test) (Experiment 6, see Figure 4A). Moreover, when participants were requested to report the size of the target objects by holding up their hands and representing the width of the cubes as the distance between their hands (Experiment 7), we obtained the same results. Compared with the normal body, bimanual object-size estimations were significantly higher during the small-body illusion (n = 14, Z = 3.296, p<0.001; Wilcoxon signed-rank test) and significantly lower during the large-body illusion (n = 14, Z = −3.296, p<0.001; Wilcoxon signed-rank test) (see Figure 4B). Importantly, the strength of the illusion of body ownership did not differ for the different artificial body sizes during experiments 6 and 7 (see Text S1 and Figure S3).


Being Barbie: the size of one's own body determines the perceived size of the world.

van der Hoort B, Guterstam A, Ehrsson HH - PLoS ONE (2011)

Results of Experiments 6–8: Own body size effect on size perception.The body size effect on verbal size estimation (A) and hand aperture (B) as a percentage deviation from the average estimation of all trials and the effect of the ownership illusion on hand aperture as a percentage deviation from corresponding asynchronous condition (C). * p<0.05, ** p<0.01, *** p<0.001. Error bars indicate SEM.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3102093&req=5

pone-0020195-g004: Results of Experiments 6–8: Own body size effect on size perception.The body size effect on verbal size estimation (A) and hand aperture (B) as a percentage deviation from the average estimation of all trials and the effect of the ownership illusion on hand aperture as a percentage deviation from corresponding asynchronous condition (C). * p<0.05, ** p<0.01, *** p<0.001. Error bars indicate SEM.
Mentions: Compared with the illusion of owning a normal-sized artificial body, participants gave significantly higher verbal estimates of cube size during the small-body illusion (n = 14, Z = 2.982, p<0.005; Wilcoxon signed-rank test) and significantly lower estimates when experiencing the large-body illusion (n = 14, Z = −1.713, p<0.05; Wilcoxon signed-rank test) (Experiment 6, see Figure 4A). Moreover, when participants were requested to report the size of the target objects by holding up their hands and representing the width of the cubes as the distance between their hands (Experiment 7), we obtained the same results. Compared with the normal body, bimanual object-size estimations were significantly higher during the small-body illusion (n = 14, Z = 3.296, p<0.001; Wilcoxon signed-rank test) and significantly lower during the large-body illusion (n = 14, Z = −3.296, p<0.001; Wilcoxon signed-rank test) (see Figure 4B). Importantly, the strength of the illusion of body ownership did not differ for the different artificial body sizes during experiments 6 and 7 (see Text S1 and Figure S3).

Bottom Line: These effects were quantified in ten separate experiments with complementary verbal, questionnaire, manual, walking, and physiological measures.Importantly, despite identical retinal input, this "body size effect" was greater when the participants experienced a sense of ownership of the artificial bodies compared to a control condition in which ownership was disrupted.Thus, our own body size affects how we perceive the world.

View Article: PubMed Central - PubMed

Affiliation: Brain, Body and Self Laboratory, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden. bvdhoort@gmail.com

ABSTRACT
A classical question in philosophy and psychology is if the sense of one's body influences how one visually perceives the world. Several theoreticians have suggested that our own body serves as a fundamental reference in visual perception of sizes and distances, although compelling experimental evidence for this hypothesis is lacking. In contrast, modern textbooks typically explain the perception of object size and distance by the combination of information from different visual cues. Here, we describe full body illusions in which subjects experience the ownership of a doll's body (80 cm or 30 cm) and a giant's body (400 cm) and use these as tools to demonstrate that the size of one's sensed own body directly influences the perception of object size and distance. These effects were quantified in ten separate experiments with complementary verbal, questionnaire, manual, walking, and physiological measures. When participants experienced the tiny body as their own, they perceived objects to be larger and farther away, and when they experienced the large-body illusion, they perceived objects to be smaller and nearer. Importantly, despite identical retinal input, this "body size effect" was greater when the participants experienced a sense of ownership of the artificial bodies compared to a control condition in which ownership was disrupted. These findings are fundamentally important as they suggest a causal relationship between the representations of body space and external space. Thus, our own body size affects how we perceive the world.

Show MeSH
Related in: MedlinePlus