The Influence Of Word Motion Features On The Embodied Representation Of Abstract Verb

How concepts are represented in the brain? The grounded cognition or embodied cognition theories assume that conceptual representations are essentially rooted in modal experiential information.Concepts are represented through cell assemblies distributed over several distinct brain areas including regions responsible for sensorimotor,introspective and emotional processes.Abstract concepts,however,which do not refer to entities with a direct sensory-motor experience,have challenged the embodied theories.Taking verbs as an example,it is still debated whether abstract verbs meaning are represented in the sensorimotor system.While some findings have provided evidence that abstract verbs may be represented in the sensorimotor system,some others did not found any activation in the motor-related areas during the processing of abstract verbs.After sorting out and analyzing the previous studies,it can be speculated that the involvement of the motor system in the representations of abstract verbs is modulated by the motor features.Abstract verbs with more direct motor experiences acquired during their learning are more likely to be predominant in the motor features and accordingly grounded much more in the motor system.Previous studies overlooked differences in the motor features when selecting abstract verbs.Therefore,the present study put the focus on the effect of motor features of abstract verbs on their representations in the motor system and provided an explanation for the variance of previous results.Importantly,the results of this study have supported and extended the embodied multiple representation theories of abstract concepts,and highlighted the critical role of sensorimotor experience in the embodiment and learning of abstract concepts.Based on the previous studies and the embodied cognitive theories,we put forward the following questions.1.Is there any difference in the involvement of the motor system during the processing of abstract verbs with high and low motor features? 2.If the answer of the first question is yes,the following question is: does the motor feature play a causal role in the embodied representations of abstract verbs? 3.Is there a greater activation of peripheral motor system during the processing of abstract verbs?To address these questions,the present study designed four sub studies including behavioral,fMRI and EMG experiments.Study 1 explored the effect of motor features on the involvement of the motor system during the processing of abstract verbs through two experiments,using the typical embodied paradigm-the Action-sentence Compatibility Effect(ACE).The results found ACE only during the processing of concrete verbs(exp.1)and abstract verbs with high motor features,but not during the processing of abstract verbs with low motor features(exp.2).These findings confirmed the relationship between the motor features and the involvement of the motor system during the processing of abstract verbs.Study 2,using the learning-test paradigm,further investigated the causal role of the motor features in the involvement of the motor system during the processing of abstract verbs through two experiments.The results showed that,after increasing motor features in the abstract verbs with low motor features(exp.3)or in the novel abstract verbs(exp.4)during the learning phase,ACE was observed in the test task requiring semantic processing(exps.3a and 4a),but not in the test task requiring no semantic processing(exps.3b and 4b).These findings demonstrated the causal link between the motor features and abstract verbs representations in the motor system from the behavioral aspect.Study 3 adopted the experimental paradigm and procedures of Study 2,to examine whether the increase of motor features in the novel abstract verbs cause the representations more in the motor system in an fMRI experiment(exp.5).As expected,the results found greater activation in the motor-related areas(eg.left precentral gyrus)to the learned novel abstract verbs after an increase of the motor features,which provided the neural evidence for the causal role of the motor features in the embodied representations of abstract verbs.Study 4 focused on the spontaneous activity of forearm muscle during the processing of the learned novel abstract verbs after an increase of motor features,with the aim to explore the motor resonance in the peripheral motor system.The results showed that both action verbs and the learned novel abstract verbs processing elicited an enhanced EMG activity of the right extensor digitorum muscle(exp.6).In conclusion,the present study has proposed and confirmed the causal role of the motor features in the embodied representations(ie.representations in the motor system)of abstract verbs.The main findings are as follows.Motor system is involved in the abstract verb processing,but the involvement is causally affected by the motor features in the abstract verbs.Increasing the motor features could make the representations of the abstract verbs more dependent on the motor system.The effect of motor features on the recruitment of the motor system during the processing of abstract verbs were task-dependent.Moreover,after an increase of the motor features,the learned novel abstract verbs processing elicited motor resonance in the peripheral motor system.This study provides support for the causal link between the motor features of the abstract verbs and their representations in the motor system,and explains the inconsistent results of the previous studies by highlighting the role of motor features in the abstract verbs.Furthermore,consistent with the grounded cognition framework,the results suggest that abstract concepts are grounded in modality-specific brain systems depending on their conceptual feature content.