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Individual differences in reading social intentions from motor deviants.

Lewkowicz D, Quesque F, Coello Y, Delevoye-Turrell YN - Front Psychol (2015)

Bottom Line: Video clips were sliced and normalized to control for either the reaction times (RTs) or/and the movement times (MTs) of the grasping action.Tested in a second group of participants, results showed that the detection of social intention relies on the variation of both RT and MT that are implicitly perceived in the grasping action.The ability to use implicitly these motor deviants for action-outcome understanding would be the key to intuitive social interaction.

View Article: PubMed Central - PubMed

Affiliation: SCALab, UMR CNRS 9193, Department of Psychology, Université de Lille , Villeneuve-d'Ascq, France.

ABSTRACT
As social animals, it is crucial to understand others' intention. But is it possible to detect social intention in two actions that have the exact same motor goal? In the present study, we presented participants with video clips of an individual reaching for and grasping an object to either use it (personal trial) or to give his partner the opportunity to use it (social trial). In Experiment 1, the ability of naïve participants to classify correctly social trials through simple observation of short video clips was tested. In addition, detection levels were analyzed as a function of individual scores in psychological questionnaires of motor imagery, visual imagery, and social cognition. Results revealed that the between-participant heterogeneity in the ability to distinguish social from personal actions was predicted by the social skill abilities. A second experiment was then conducted to assess what predictive mechanism could contribute to the detection of social intention. Video clips were sliced and normalized to control for either the reaction times (RTs) or/and the movement times (MTs) of the grasping action. Tested in a second group of participants, results showed that the detection of social intention relies on the variation of both RT and MT that are implicitly perceived in the grasping action. The ability to use implicitly these motor deviants for action-outcome understanding would be the key to intuitive social interaction.

No MeSH data available.


Related in: MedlinePlus

(A) A typical example of the video stimuli that was used both in Experiments 1 and 2 to test the role of motor deviants for the categorization of social and personal object-centered actions. One can note the neutral context that was used with the placement of 3D reflexive markers that provided us the means to verify the kinematic deviants between social and personal movements during the validation phase of the video database. (B) Velocity curves of the corresponding trial illustrating the double bell shaped profiles that are observed in the present reach to grasp task. Reaction times (RT in ms) and movement times of the first element of the sequence (MT of reach in ms) may have been used by the observers to dissociate social from personal actions.
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Figure 1: (A) A typical example of the video stimuli that was used both in Experiments 1 and 2 to test the role of motor deviants for the categorization of social and personal object-centered actions. One can note the neutral context that was used with the placement of 3D reflexive markers that provided us the means to verify the kinematic deviants between social and personal movements during the validation phase of the video database. (B) Velocity curves of the corresponding trial illustrating the double bell shaped profiles that are observed in the present reach to grasp task. Reaction times (RT in ms) and movement times of the first element of the sequence (MT of reach in ms) may have been used by the observers to dissociate social from personal actions.

Mentions: A particular attention was taken to suppress all contextual information from the video clips (see Figure 1A). Only the arm of the actor and the target object were framed within the video clips of the 30 preparatory actions. The video clips that were used as stimuli consisted in a sequential action of two motor elements (1) reach to grasp and (2) move to place. The video clips were cut exactly one frame after the actor finished placing the object. Movies were compressed with FFdshow codec (MJPEG) at 30 frames per second with a screen resolution of 640 × 480 pixels. 3D kinematics were analyzed with RTMocap toolbox (Lewkowicz and Delevoye-Turrell, 2015). Positional data points were filtered using a dual fourth-order Butterworth low-pass filter (fc = 15 Hz; forward and backward) and tangential 3D instantaneous velocities were calculated. A threshold of 20 mm·s–1 was used to determine the onset of movement (reaction time, RT). All velocity trajectories were bell shaped and consisted in two “bells,” the first corresponding to the reach to grasp element, the second being the move to place element of the preparatory action. The amplitude of peak velocity of the first element (APV1) was extracted using the local maxima (first 0-crossing of acceleration). The end of the first element was determined as the time of occurrence of the local minima (second 0-crossing of acceleration) between the first and the second element-peaks (see vertical arrow in Figure 1). The duration of the first element (MT1) was calculated as the time interval between the onset and the end of the first element. The amplitude of the peak height of trajectories (APH1) was defined as the maximum z coordinate of the wrist measured in the grasping element and the lift to place element. APV2, MT2, and APH2 are the corresponding kinematic parameters described above but extracted from the second move to place element of the motor sequence. Table 1 presents the characteristics of the movement parameters that were measured, e.g., RT, MT, peak wrist velocity, and height of hand trajectory. Figure 2 presents the scatterplot of amplitude of peak velocity against MT in order to confirm none negligible proportions of the plots that are discriminative between social and personal trials. Using comparison to the median values, pre-analysis confirmed the possibility to dissociate personal from social trials on the basis of RT, MT and height of grasping phase (APH).


Individual differences in reading social intentions from motor deviants.

Lewkowicz D, Quesque F, Coello Y, Delevoye-Turrell YN - Front Psychol (2015)

(A) A typical example of the video stimuli that was used both in Experiments 1 and 2 to test the role of motor deviants for the categorization of social and personal object-centered actions. One can note the neutral context that was used with the placement of 3D reflexive markers that provided us the means to verify the kinematic deviants between social and personal movements during the validation phase of the video database. (B) Velocity curves of the corresponding trial illustrating the double bell shaped profiles that are observed in the present reach to grasp task. Reaction times (RT in ms) and movement times of the first element of the sequence (MT of reach in ms) may have been used by the observers to dissociate social from personal actions.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4538241&req=5

Figure 1: (A) A typical example of the video stimuli that was used both in Experiments 1 and 2 to test the role of motor deviants for the categorization of social and personal object-centered actions. One can note the neutral context that was used with the placement of 3D reflexive markers that provided us the means to verify the kinematic deviants between social and personal movements during the validation phase of the video database. (B) Velocity curves of the corresponding trial illustrating the double bell shaped profiles that are observed in the present reach to grasp task. Reaction times (RT in ms) and movement times of the first element of the sequence (MT of reach in ms) may have been used by the observers to dissociate social from personal actions.
Mentions: A particular attention was taken to suppress all contextual information from the video clips (see Figure 1A). Only the arm of the actor and the target object were framed within the video clips of the 30 preparatory actions. The video clips that were used as stimuli consisted in a sequential action of two motor elements (1) reach to grasp and (2) move to place. The video clips were cut exactly one frame after the actor finished placing the object. Movies were compressed with FFdshow codec (MJPEG) at 30 frames per second with a screen resolution of 640 × 480 pixels. 3D kinematics were analyzed with RTMocap toolbox (Lewkowicz and Delevoye-Turrell, 2015). Positional data points were filtered using a dual fourth-order Butterworth low-pass filter (fc = 15 Hz; forward and backward) and tangential 3D instantaneous velocities were calculated. A threshold of 20 mm·s–1 was used to determine the onset of movement (reaction time, RT). All velocity trajectories were bell shaped and consisted in two “bells,” the first corresponding to the reach to grasp element, the second being the move to place element of the preparatory action. The amplitude of peak velocity of the first element (APV1) was extracted using the local maxima (first 0-crossing of acceleration). The end of the first element was determined as the time of occurrence of the local minima (second 0-crossing of acceleration) between the first and the second element-peaks (see vertical arrow in Figure 1). The duration of the first element (MT1) was calculated as the time interval between the onset and the end of the first element. The amplitude of the peak height of trajectories (APH1) was defined as the maximum z coordinate of the wrist measured in the grasping element and the lift to place element. APV2, MT2, and APH2 are the corresponding kinematic parameters described above but extracted from the second move to place element of the motor sequence. Table 1 presents the characteristics of the movement parameters that were measured, e.g., RT, MT, peak wrist velocity, and height of hand trajectory. Figure 2 presents the scatterplot of amplitude of peak velocity against MT in order to confirm none negligible proportions of the plots that are discriminative between social and personal trials. Using comparison to the median values, pre-analysis confirmed the possibility to dissociate personal from social trials on the basis of RT, MT and height of grasping phase (APH).

Bottom Line: Video clips were sliced and normalized to control for either the reaction times (RTs) or/and the movement times (MTs) of the grasping action.Tested in a second group of participants, results showed that the detection of social intention relies on the variation of both RT and MT that are implicitly perceived in the grasping action.The ability to use implicitly these motor deviants for action-outcome understanding would be the key to intuitive social interaction.

View Article: PubMed Central - PubMed

Affiliation: SCALab, UMR CNRS 9193, Department of Psychology, Université de Lille , Villeneuve-d'Ascq, France.

ABSTRACT
As social animals, it is crucial to understand others' intention. But is it possible to detect social intention in two actions that have the exact same motor goal? In the present study, we presented participants with video clips of an individual reaching for and grasping an object to either use it (personal trial) or to give his partner the opportunity to use it (social trial). In Experiment 1, the ability of naïve participants to classify correctly social trials through simple observation of short video clips was tested. In addition, detection levels were analyzed as a function of individual scores in psychological questionnaires of motor imagery, visual imagery, and social cognition. Results revealed that the between-participant heterogeneity in the ability to distinguish social from personal actions was predicted by the social skill abilities. A second experiment was then conducted to assess what predictive mechanism could contribute to the detection of social intention. Video clips were sliced and normalized to control for either the reaction times (RTs) or/and the movement times (MTs) of the grasping action. Tested in a second group of participants, results showed that the detection of social intention relies on the variation of both RT and MT that are implicitly perceived in the grasping action. The ability to use implicitly these motor deviants for action-outcome understanding would be the key to intuitive social interaction.

No MeSH data available.


Related in: MedlinePlus