Cognitive Neural Basis For Motion Prediction Of Others In Synchronised Joint Movement

Synchronicity in behavior between individuals is a common form of cooperation.Synchronized joint action,defined as the synchronization of movements or actions based on interaction with each other.Motor predictions of others is the key process to achieve movement synchronization in synchronized joint action.The goal and motion information are the major cue to predict other's movements.The common coding theory claims that the task representation based on goal information is the precondition for motor prediction,which guides the processing of motor prediction based on motion information.The predictive joint-action model claims that the feedback cue in motion information that contain the information of action outcome can be used to optimize the motor prediction iteratively.Which view can better explain the cognitive mechanism of motor prediction in synchronized joint action? How do motor predictions based on different cues affect movement synchronization and neural patterns between individuals? In this paper,three studies consisted of eight experiments using a joint reaching task were conducted to discuss the above questions.Study1 explored the effect of cooperative intention on motor prediction of others in synchronized joint action,which included experiments 1a,1b,and experiments 2a,2b.Experiment 1a explored the effect of joint context and motion mode on individual movement.18 pairs of college students were asked to execute reaching movements with a fixed distance.Movement time was recorded through the motion capture system.Using a 2(joint context: without,with)× 2(motion mode: self-paced speed,fast speed)within design,the results showed that the main effect of joint context was significant;the main effect of motion mode was significant;the interaction effect of joint context and motion mode was significant.The movement time of selfpaced speed was significantly longer than that of fast speed when there was a joint context.When the motion mode was fast speed,the movement time without joint context was significantly longer than that with joint context.Experiment 1b explored the effect of joint context and motion manner on hemodynamic responses of individual movement.18 pairs of college students were asked to execute reaching movements with a fixed distance.Brain activities were recorded through functional near-infrared spectroscopy.Using a 2(joint context: without,with)× 2(motion mode: self-paced speed,fast speed)within design,the results showed that the main effect of joint context was significant.The activation of the premotor and supplementary motor cortex was significantly stronger with joint context than without joint context.Experiment 2a explored the effect of the type of joint intention on individual movement.18 pairs of college students were asked to execute reaching movements with a fixed distance.Movement time was recorded through the motion capture system.Using a single factor 3(type of joint intention: no intention,cooperation,competition)within design,the results showed that the main effect of the type of joint intention was significant.Compared with no intention,the movement time with cooperation or competition was shorter,and the movement time was longer in cooperation than in competition.Experiment 2b explored the effect of the type of joint intention on hemodynamic responses of individual movement.18 pairs of college students were asked to execute reaching movements with a fixed distance.Brain activities were recorded through functional near-infrared spectroscopy.Using a single factor 3(type of joint intention: no intention,cooperation,competition)within design,the results showed that the main effect of the type of joint intention was significant.The activation of the temporoparietal junction was significantly weaker in the no intention condition than in the competition condition.Study 2 explored the cognitive mechanism of motor predictions of others in synchronized joint action,which included experiment 3,experiment 4,experiment 5,and experiment 6.Experiment 3 explored the effect of task cue and distance differences on motor prediction of others in synchronized joint action.26 pairs of college students were asked to execute synchronized reaching movements with an unfixed distance.Movement time and synchronization performances were recorded through the motion capture system,and the mean absolute asynchrony was represented as the synchronization performances between pairs of participants(lower asynchrony indicated better synchronization performances).Using a 2(task cue: without,with)× 4(distance differences: ?0,?1,?2,?3)within design,?1,?2,?3 represented the differences of motor distances between pairs of participants(the motor distance is equal at ?0).The greater the number,the greater the distance between individuals.The results showed that:(1)The mean absolute asynchrony.The main effect of the task cue was significant;The main effect of the distance differences was significant;The interaction effect between the task cue and the distance differences were significant.When there was no task cue,the mean absolute asynchrony was significantly lower in ?0 and ?1 than in ?2 and ?3.When the task cue was offered,the mean absolute asynchrony was significantly lower in ?0,?1,and ?2 than in ?3.For ?0,?2,and ?3,the mean absolute asynchrony without task cue was significantly higher than with task cue.(2)Movement time.2(task cue: without,with)×(relationships of motor distances: closer farther)repeated measures ANOVAs revealed that the main effect of relationships of motor distances was significant;The interaction effect of task cue and relationships of motor distances was significant.When there was no task cue,the movement time of closer motor distances was significantly shorter than that of farther motor distances.For farther motor distances,the movement time without task cue was significantly longer than that with task cue.Experiment 4 explored the effect of feedback cue(visual)and distance differences on motor prediction of others in synchronized joint action.26 pairs of college students were asked to execute synchronized reaching movements with an unfixed distance.Movement time and synchronization performances were recorded through the motion capture system.Using a 2(feedback cue: without,with)× 4(distance differences: ?0,?1,?2,?3)within design.The results showed that:(1)The mean absolute asynchrony.The main effect of the feedback cue was significant;The main effect of the distance differences was significant;The interaction effect between the feedback cue and the distance differences were significant.The mean absolute asynchrony was significantly lower in ?0 and ?1 than in ?2 and ?3 regardless of feedback cue.And the mean absolute asynchrony without feedback cue was significantly higher than that with feedback cue regardless of distance differences.(2)Movement time.2(feedback cue: without,with)×(relationships of motor distances:closer farther)repeated measures ANOVAs revealed that the main effect feedback cue was significant;The main effect of relationships of motor distances was significant;The interaction effect of feedback cue and relationships of motor distances was significant.The movement time of closer motor distances was significantly shorter than that of farther motor distances regardless of feedback cue.The movement time without feedback cue was significantly longer than that with feedback cue regardless of relationships of motor distances.Experiment 5 explored the effect of feedback cue(words)and distance differences on motor prediction of others in synchronized joint action.24 pairs of college students were asked to execute synchronized reaching movements with an unfixed distance.Response time and synchronization performances were recorded through the computer.Using a 2(feedback cue: without,with)×4(distance differences: ?0,?1,?2,?3)within design.The results showed that:(1)The mean absolute asynchrony.The main effect of the feedback cue was significant,the mean absolute asynchrony without feedback cue was significantly higher than with feedback cue.The main effect of the distance differences was significant,the mean absolute asynchrony was significantly lower in ?1 than in ?3.(2)Response time.2(feedback cue: without,with)×(relationships of motor distances: closer farther)repeated measures ANOVAs revealed that the main effect of feedback cue was significant;The main effect of relationships of motor distances was significant;The interaction effect of feedback cue and relationships of motor distances was significant.The response time of closer motor distances was significantly shorter than that of farther motor distances regardless of feedback cue.The response time without feedback cue was significantly longer than that with feedback cue regardless of relationships of motor distances.Experiment 6 explored the effect of cue type and distance differences on motor prediction of others in synchronized joint action.24 pairs of college students were asked to execute synchronized reaching movements with an unfixed distance.Response time and synchronization performances were recorded through the computer.Using a 2(cue type: single,double)×4(distance differences: ?0,?1,?2,?3)within design.The results showed that:(1)The mean absolute asynchrony.The main effect of the distance differences was significant,the mean absolute asynchrony was significantly lower in ?0 and ?1 than in ?3.(2)Response time.2(cue type: single double)×(relationships of motor distances: closer farther)repeated measures ANOVAs revealed that the main effect of relationships of motor distances was significant;The interaction effect of cue type and relationships of motor distances was significant.For the single cue,the response time of closer motor distances was significantly shorter than that of farther motor distances.For farther motor distances,the response time in the single cue was significantly longer than that in the double cue.Study 3 explored the neural substrate of motor prediction of others in synchronized joint action,which included experiment 7 and experiment 8.Experiment 7 explored the effect of task cue and distance differences on motor prediction of others in synchronized joint action.24 pairs of college students were asked to execute synchronized reaching movements with unfixed distance.Brain activities were recorded through the functional near-infrared spectroscopy.Using a 2(task cue: without,with)× 4(distance differences: ?0,?1,?2,?3)within design.The results showed that the main effect of the task cue was significant.Brain activation in the premotor and supplementary motor cortex was significantly higher without task cue than that with task cue.Experiment 8 explored the effect of feedback cue and distance differences on motor prediction of others in synchronized joint action.24 pairs of college students were asked to execute synchronized reaching movements with unfixed distance.Brain activities were recorded through the functional near-infrared spectroscopy.Using a 2(feedback cue: without,with)× 4(distance differences: ?0,?1,?2,?3)within design.The results showed that the main effect of the feedback cue was significant.Brain activation in the dorsolateral prefrontal cortex and the premotor and supplementary motor cortex were significantly higher without feedback cue than that with feedback cue.Based on the above results,the following conclusions can be drawn:(1)During synchronized joint action,individuals regulate self-other related processes based on cooperative intention to predict others' movements and adjust motor performance.(2)The synchronization of movements in synchronized joint action is achieved via two routes:the goal information of others and the motor information of others,which has a different impact on synchronized joint action.(3)The task cue and feedback cue have a different effect in the motor prediction of others.The feedback cue predicts others' movements based on movement time,which plays a critical role in synchronized joint action.(4)The temporoparietal junction generally participates in the social interaction between individuals during synchronized joint action.Motor prediction of others based on the task cue is related to the neural activity in premotor and supplementary motor cortex,while motor prediction of others based on the task cue is related to the neural activity in dorsolateral prefrontal cortex and premotor and supplementary motor cortex.