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Give It a Tug and Feel It Grow: Extending Body Perception Through the Universal Nature of Illusory Finger Stretching

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ABSTRACT

If British teenage boy asks you to pull his finger, it is usually an indication that he simultaneously wishes to break wind. If you were to tell him that you could pull his finger and stretch it to twice its length, you might expect a similarly irreverent response yet when we pulled the fingers of nearly 600 children and adolescents, 93% reported the illusion of stretching. Grossly distorted body representations need not be the preserve of clinical disorders and can reliably be induced in healthy participants across all ages.

No MeSH data available.


Related in: MedlinePlus

Upon placing his or her hand inside MIRAGE (upper left), each participant was instructed to make a fist and extend the index finger as if pointing at the experimenter (although it is rude to point, it was excused on this occasion). The experimenter placed a wooden block against the fingertip and asked whether the participant could feel it. The block was immediately positioned further away with the words, “But when I move it back here you cannot touch it without moving your hand, can you?” Once agreement had been obtained, the experimenter grasped the distal phalanx (end) of the index finger and gently pulled; firm enough to straighten the collateral ligaments of the finger, but not enough to cause discomfort. Simultaneously, the portion of the live video corresponding to the proximal interphalangeal joint (middle or second knuckle) expanded in such a way that the visible area gradually doubled outwards until it reached the extreme ends of the finger (see Supplemental Video http://www.psychology.nottingham.ac.uk/staff/rwn/Giveitatugsupplementalvideo.mp4). After the stretch, which took 1 to 3 seconds depending upon actual finger length, the experimenter reproduced the wooden block and again touched it against the fingertip with the words, “But now you can!” At this point, the experimenter posed the question, “Does it feel like your finger has really stretched?” to which the participant responded “yes” or “no.”
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fig1-2041669515599310: Upon placing his or her hand inside MIRAGE (upper left), each participant was instructed to make a fist and extend the index finger as if pointing at the experimenter (although it is rude to point, it was excused on this occasion). The experimenter placed a wooden block against the fingertip and asked whether the participant could feel it. The block was immediately positioned further away with the words, “But when I move it back here you cannot touch it without moving your hand, can you?” Once agreement had been obtained, the experimenter grasped the distal phalanx (end) of the index finger and gently pulled; firm enough to straighten the collateral ligaments of the finger, but not enough to cause discomfort. Simultaneously, the portion of the live video corresponding to the proximal interphalangeal joint (middle or second knuckle) expanded in such a way that the visible area gradually doubled outwards until it reached the extreme ends of the finger (see Supplemental Video http://www.psychology.nottingham.ac.uk/staff/rwn/Giveitatugsupplementalvideo.mp4). After the stretch, which took 1 to 3 seconds depending upon actual finger length, the experimenter reproduced the wooden block and again touched it against the fingertip with the words, “But now you can!” At this point, the experimenter posed the question, “Does it feel like your finger has really stretched?” to which the participant responded “yes” or “no.”

Mentions: Each participant received a single finger stretch adhering to the protocol outlined in Figure 1. Overall, 93% reported the illusion that their finger had been stretched (Figure 2). Typical reactions were laughter, disgust, amazement, and drooling. The overriding verbal description was that it was “weird” (other descriptions cannot be printed here). For analysis, children were grouped into 2-year bins by gender to investigate two alternative hypothetical outcomes: (a) if sensory integration matures slowly (Assaiante, Barlaam, Cignetti, & Vaugoyeau, 2014), then susceptibility should increase with age; (b) given the skeptical and truculent nature of teenagers (reference your own life), with greater experience of what fingers should or should not do, susceptibility should decrease with age. However, no differences between groups were observed after corrections for multiple comparisons (min: χ2(1) = 5.35), supporting neither hypothesis. These results were obtained outside the laboratory, and while some participants were told to expect a stretched finger (something which deserves further investigation), the illusion worked consistently regardless of skepticism, gullibility, prior expectations, positive or negative peer pressure, background noise or sensory load.Figure 1.


Give It a Tug and Feel It Grow: Extending Body Perception Through the Universal Nature of Illusory Finger Stretching
Upon placing his or her hand inside MIRAGE (upper left), each participant was instructed to make a fist and extend the index finger as if pointing at the experimenter (although it is rude to point, it was excused on this occasion). The experimenter placed a wooden block against the fingertip and asked whether the participant could feel it. The block was immediately positioned further away with the words, “But when I move it back here you cannot touch it without moving your hand, can you?” Once agreement had been obtained, the experimenter grasped the distal phalanx (end) of the index finger and gently pulled; firm enough to straighten the collateral ligaments of the finger, but not enough to cause discomfort. Simultaneously, the portion of the live video corresponding to the proximal interphalangeal joint (middle or second knuckle) expanded in such a way that the visible area gradually doubled outwards until it reached the extreme ends of the finger (see Supplemental Video http://www.psychology.nottingham.ac.uk/staff/rwn/Giveitatugsupplementalvideo.mp4). After the stretch, which took 1 to 3 seconds depending upon actual finger length, the experimenter reproduced the wooden block and again touched it against the fingertip with the words, “But now you can!” At this point, the experimenter posed the question, “Does it feel like your finger has really stretched?” to which the participant responded “yes” or “no.”
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2 - License 3
Show All Figures
getmorefigures.php?uid=PMC5016819&req=5

fig1-2041669515599310: Upon placing his or her hand inside MIRAGE (upper left), each participant was instructed to make a fist and extend the index finger as if pointing at the experimenter (although it is rude to point, it was excused on this occasion). The experimenter placed a wooden block against the fingertip and asked whether the participant could feel it. The block was immediately positioned further away with the words, “But when I move it back here you cannot touch it without moving your hand, can you?” Once agreement had been obtained, the experimenter grasped the distal phalanx (end) of the index finger and gently pulled; firm enough to straighten the collateral ligaments of the finger, but not enough to cause discomfort. Simultaneously, the portion of the live video corresponding to the proximal interphalangeal joint (middle or second knuckle) expanded in such a way that the visible area gradually doubled outwards until it reached the extreme ends of the finger (see Supplemental Video http://www.psychology.nottingham.ac.uk/staff/rwn/Giveitatugsupplementalvideo.mp4). After the stretch, which took 1 to 3 seconds depending upon actual finger length, the experimenter reproduced the wooden block and again touched it against the fingertip with the words, “But now you can!” At this point, the experimenter posed the question, “Does it feel like your finger has really stretched?” to which the participant responded “yes” or “no.”
Mentions: Each participant received a single finger stretch adhering to the protocol outlined in Figure 1. Overall, 93% reported the illusion that their finger had been stretched (Figure 2). Typical reactions were laughter, disgust, amazement, and drooling. The overriding verbal description was that it was “weird” (other descriptions cannot be printed here). For analysis, children were grouped into 2-year bins by gender to investigate two alternative hypothetical outcomes: (a) if sensory integration matures slowly (Assaiante, Barlaam, Cignetti, & Vaugoyeau, 2014), then susceptibility should increase with age; (b) given the skeptical and truculent nature of teenagers (reference your own life), with greater experience of what fingers should or should not do, susceptibility should decrease with age. However, no differences between groups were observed after corrections for multiple comparisons (min: χ2(1) = 5.35), supporting neither hypothesis. These results were obtained outside the laboratory, and while some participants were told to expect a stretched finger (something which deserves further investigation), the illusion worked consistently regardless of skepticism, gullibility, prior expectations, positive or negative peer pressure, background noise or sensory load.Figure 1.

View Article: PubMed Central - PubMed

ABSTRACT

If British teenage boy asks you to pull his finger, it is usually an indication that he simultaneously wishes to break wind. If you were to tell him that you could pull his finger and stretch it to twice its length, you might expect a similarly irreverent response yet when we pulled the fingers of nearly 600 children and adolescents, 93% reported the illusion of stretching. Grossly distorted body representations need not be the preserve of clinical disorders and can reliably be induced in healthy participants across all ages.

No MeSH data available.


Related in: MedlinePlus