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Crossed hands strengthen and diversify proprioceptive drift in the self-touch illusion.

Kodaka K, Ishihara Y - Front Hum Neurosci (2014)

Bottom Line: Moreover, it is interesting that strong PD with dominance of the receptive hand, which did not appear in the uncrossed condition, was observed frequently.We also found that a small number of participants exhibited quite a different pattern of the PD in the identical posture.On the basis of the results, we analyze in detail how the dominant hand on the PD is determined in the STI.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Design and Architecture, Nagoya City University Nagoya, Japan.

ABSTRACT
In the self-touch illusion (STI), some can feel that both hands are touching each other even when they are separated actually. This is achieved by giving synchronized touches to both hands. Because the STI involves both hands (an administrating hand and a receptive hand) of a single person, two types of proprioceptive drifts (PDs) simultaneously occur in such a way that both hands are attracted to each other. It is known that the PD distance is generally larger for the administrating hand than for the receptive hand when the two hands are uncrossed. However, it remains unclear why such an asymmetrical relationship is observed universally. In this study, we conducted two types of experiment to induce the STI. The first experiment involved four conditions combining a factor of "whether the hands are uncrossed or crossed" and a factor of "whether the administrating hand is resting or active on the surface," with the receptive (left) hand located at the body's midline. The result demonstrated that crossing hands and resting on surface (ROS) induced the STI. Specifically, crossing hands enhanced the amount of PD distance by more than two or three times. Moreover, it is interesting that strong PD with dominance of the receptive hand, which did not appear in the uncrossed condition, was observed frequently. The second experiment collected seven "illusion-sensitive" participants from the first experiment, all of whom had a strong tendency to feel the self-touch, and examined the effect of the location of the body midline on the PD when hands are crossed with the administrating hand ROS. The result demonstrated that the dominant hand on the PD completely differed among participants, but was relatively stable over the midline position and time in the same person. We also found that a small number of participants exhibited quite a different pattern of the PD in the identical posture. On the basis of the results, we analyze in detail how the dominant hand on the PD is determined in the STI.

No MeSH data available.


Related in: MedlinePlus

Relationship between agreement rating for illusion statement and average attractivity in four types of hand postures. Each average of attractivity was calculated from all sessions involving the same agreement rating (0–6) for the illusion statement. The number in parentheses indicates how many sessions produced the corresponding agreement rating, and the statistics depict the result of the Spearman correlation test. Error bars indicate standard error.
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Figure 7: Relationship between agreement rating for illusion statement and average attractivity in four types of hand postures. Each average of attractivity was calculated from all sessions involving the same agreement rating (0–6) for the illusion statement. The number in parentheses indicates how many sessions produced the corresponding agreement rating, and the statistics depict the result of the Spearman correlation test. Error bars indicate standard error.

Mentions: Figure 7 compares the average of attractivity values pooled from all sessions involving the identical agreement rating (0–6) for the illusion statement. As the graph obviously indicates, the attractivity strongly and positively correlated with subjective illusion strength (Spearman with n = 72, Uncrossed × Active: r = 0.467, p < 0.001; Uncrossed × ROS: r = 0.352, p < 0.01; Crossed × Active: r = 0.537, p < 0.001; Crossed × ROS: r = 0.606, p < 0.001). Specifically, the attractivity was near or less than zero when the rating was 0 or 1, whereas it jumped to near 0.5 for the ratings of 4 or 5. In sessions with the rating of 6 (“very strongly agree”), which had few samples, the attractivity was near 1.0 without exception, meaning that both index fingers touched each other on the level of the body image.


Crossed hands strengthen and diversify proprioceptive drift in the self-touch illusion.

Kodaka K, Ishihara Y - Front Hum Neurosci (2014)

Relationship between agreement rating for illusion statement and average attractivity in four types of hand postures. Each average of attractivity was calculated from all sessions involving the same agreement rating (0–6) for the illusion statement. The number in parentheses indicates how many sessions produced the corresponding agreement rating, and the statistics depict the result of the Spearman correlation test. Error bars indicate standard error.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4060641&req=5

Figure 7: Relationship between agreement rating for illusion statement and average attractivity in four types of hand postures. Each average of attractivity was calculated from all sessions involving the same agreement rating (0–6) for the illusion statement. The number in parentheses indicates how many sessions produced the corresponding agreement rating, and the statistics depict the result of the Spearman correlation test. Error bars indicate standard error.
Mentions: Figure 7 compares the average of attractivity values pooled from all sessions involving the identical agreement rating (0–6) for the illusion statement. As the graph obviously indicates, the attractivity strongly and positively correlated with subjective illusion strength (Spearman with n = 72, Uncrossed × Active: r = 0.467, p < 0.001; Uncrossed × ROS: r = 0.352, p < 0.01; Crossed × Active: r = 0.537, p < 0.001; Crossed × ROS: r = 0.606, p < 0.001). Specifically, the attractivity was near or less than zero when the rating was 0 or 1, whereas it jumped to near 0.5 for the ratings of 4 or 5. In sessions with the rating of 6 (“very strongly agree”), which had few samples, the attractivity was near 1.0 without exception, meaning that both index fingers touched each other on the level of the body image.

Bottom Line: Moreover, it is interesting that strong PD with dominance of the receptive hand, which did not appear in the uncrossed condition, was observed frequently.We also found that a small number of participants exhibited quite a different pattern of the PD in the identical posture.On the basis of the results, we analyze in detail how the dominant hand on the PD is determined in the STI.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Design and Architecture, Nagoya City University Nagoya, Japan.

ABSTRACT
In the self-touch illusion (STI), some can feel that both hands are touching each other even when they are separated actually. This is achieved by giving synchronized touches to both hands. Because the STI involves both hands (an administrating hand and a receptive hand) of a single person, two types of proprioceptive drifts (PDs) simultaneously occur in such a way that both hands are attracted to each other. It is known that the PD distance is generally larger for the administrating hand than for the receptive hand when the two hands are uncrossed. However, it remains unclear why such an asymmetrical relationship is observed universally. In this study, we conducted two types of experiment to induce the STI. The first experiment involved four conditions combining a factor of "whether the hands are uncrossed or crossed" and a factor of "whether the administrating hand is resting or active on the surface," with the receptive (left) hand located at the body's midline. The result demonstrated that crossing hands and resting on surface (ROS) induced the STI. Specifically, crossing hands enhanced the amount of PD distance by more than two or three times. Moreover, it is interesting that strong PD with dominance of the receptive hand, which did not appear in the uncrossed condition, was observed frequently. The second experiment collected seven "illusion-sensitive" participants from the first experiment, all of whom had a strong tendency to feel the self-touch, and examined the effect of the location of the body midline on the PD when hands are crossed with the administrating hand ROS. The result demonstrated that the dominant hand on the PD completely differed among participants, but was relatively stable over the midline position and time in the same person. We also found that a small number of participants exhibited quite a different pattern of the PD in the identical posture. On the basis of the results, we analyze in detail how the dominant hand on the PD is determined in the STI.

No MeSH data available.


Related in: MedlinePlus