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Automatic versus voluntary motor imitation: effect of visual context and stimulus velocity.

Bisio A, Stucchi N, Jacono M, Fadiga L, Pozzo T - PLoS ONE (2010)

Bottom Line: The present study was designed to understand if the kinematics of a previously seen stimulus primes the executed action, and if this effect is sensitive to the kinds of stimuli presented.Despite that the performance, in term of reproduced velocity, improved in a context of voluntary imitation, subjects did not replicate the observed motions exactly.These effects were not affected by the kind of stimuli used, i.e., motor responses were influenced in the same manner after dot or human observation.

View Article: PubMed Central - PubMed

Affiliation: Department of Robotics, Brain and Cognitive Sciences, Italian Institute of Technology, Genova, Italy. ambra.bisio@iit.it

ABSTRACT
Automatic imitation is the tendency to reproduce observed actions involuntarily. Though this topic has been widely treated, at present little is known about the automatic imitation of the kinematic features of an observed movement. The present study was designed to understand if the kinematics of a previously seen stimulus primes the executed action, and if this effect is sensitive to the kinds of stimuli presented. We proposed a simple imitation paradigm in which a dot or a human demonstrator moved in front of the participant who was instructed either to reach the final position of the stimulus or to imitate its motion with his or her right arm. Participants' movements were automatically contaminated by stimulus velocity when it moved according to biological laws, suggesting that automatic imitation was kinematic dependent. Despite that the performance, in term of reproduced velocity, improved in a context of voluntary imitation, subjects did not replicate the observed motions exactly. These effects were not affected by the kind of stimuli used, i.e., motor responses were influenced in the same manner after dot or human observation. These findings support the existence of low-level sensory-motor matching mechanisms that work on movement planning and represent the basis for higher levels of social interaction.

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Preliminary experiment, velocity profile.Upward (dark grey) and downward (light grey) movement velocity profile of a typical subject, normalized on amplitude and duration (MD). On the bottom the Time to Peak Velocity values (TPV) of these movements are reported.
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pone-0013506-g002: Preliminary experiment, velocity profile.Upward (dark grey) and downward (light grey) movement velocity profile of a typical subject, normalized on amplitude and duration (MD). On the bottom the Time to Peak Velocity values (TPV) of these movements are reported.

Mentions: Modulations of velocity along the trajectory were in agreement with those already described by Papaxanthis et al. [15]: the time to peak velocity values (TPV) were 0.43±0.07 and 0.5±0.06 (mean ± standard deviation) for upward and downward movements, respectively. Figure 2A shows an example of an upward and downward velocity profiles for a typical subject. The mean TPV values of participants in the two directions were statically different (F(1,15) = 37.89, p<0.01), whereas the mean velocities (V, up: 0.81±0.16 m/s, down: 0.78±0.2 m/s) were not.


Automatic versus voluntary motor imitation: effect of visual context and stimulus velocity.

Bisio A, Stucchi N, Jacono M, Fadiga L, Pozzo T - PLoS ONE (2010)

Preliminary experiment, velocity profile.Upward (dark grey) and downward (light grey) movement velocity profile of a typical subject, normalized on amplitude and duration (MD). On the bottom the Time to Peak Velocity values (TPV) of these movements are reported.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2958128&req=5

pone-0013506-g002: Preliminary experiment, velocity profile.Upward (dark grey) and downward (light grey) movement velocity profile of a typical subject, normalized on amplitude and duration (MD). On the bottom the Time to Peak Velocity values (TPV) of these movements are reported.
Mentions: Modulations of velocity along the trajectory were in agreement with those already described by Papaxanthis et al. [15]: the time to peak velocity values (TPV) were 0.43±0.07 and 0.5±0.06 (mean ± standard deviation) for upward and downward movements, respectively. Figure 2A shows an example of an upward and downward velocity profiles for a typical subject. The mean TPV values of participants in the two directions were statically different (F(1,15) = 37.89, p<0.01), whereas the mean velocities (V, up: 0.81±0.16 m/s, down: 0.78±0.2 m/s) were not.

Bottom Line: The present study was designed to understand if the kinematics of a previously seen stimulus primes the executed action, and if this effect is sensitive to the kinds of stimuli presented.Despite that the performance, in term of reproduced velocity, improved in a context of voluntary imitation, subjects did not replicate the observed motions exactly.These effects were not affected by the kind of stimuli used, i.e., motor responses were influenced in the same manner after dot or human observation.

View Article: PubMed Central - PubMed

Affiliation: Department of Robotics, Brain and Cognitive Sciences, Italian Institute of Technology, Genova, Italy. ambra.bisio@iit.it

ABSTRACT
Automatic imitation is the tendency to reproduce observed actions involuntarily. Though this topic has been widely treated, at present little is known about the automatic imitation of the kinematic features of an observed movement. The present study was designed to understand if the kinematics of a previously seen stimulus primes the executed action, and if this effect is sensitive to the kinds of stimuli presented. We proposed a simple imitation paradigm in which a dot or a human demonstrator moved in front of the participant who was instructed either to reach the final position of the stimulus or to imitate its motion with his or her right arm. Participants' movements were automatically contaminated by stimulus velocity when it moved according to biological laws, suggesting that automatic imitation was kinematic dependent. Despite that the performance, in term of reproduced velocity, improved in a context of voluntary imitation, subjects did not replicate the observed motions exactly. These effects were not affected by the kind of stimuli used, i.e., motor responses were influenced in the same manner after dot or human observation. These findings support the existence of low-level sensory-motor matching mechanisms that work on movement planning and represent the basis for higher levels of social interaction.

Show MeSH