The assumed motor capabilities of a partner influence motor imagery in a joint serial disc transfer task.

Motor imagery (MI) of one's own movements is thought to involve the sub-threshold activation of one's own motor codes. Movement coordination during joint action is thought to occur because co-actors integrate a simulation of their own actions with the simulated actions of the partner. The present experiments gained insight into MI of joint action by investigating if and how the assumed motor capabilitiesof the imaginary partner affected MI. Participants performed a serial disc transfer task alone and then imagined performing the same task alone and with an imagined partner. In the individual tasks, participants transferred all four discs. In the joint task, participants imagined themselves transferring the first 2 discs and a partner transferring the last 2 discs. The description of the imagined partner (high/low performer) was manipulated across blocks to determine if participants adapted their MI of the joint task based on the partner's characteristics. Results revealed that imagined movement times (MTs) were shorter when the description of the imagined partner was a 'high' performer compared to a 'low' performer. Interestingly, participants not only adjusted the partner's portion of the task, but they also adjusted their own portion of the task - imagined MTs of the first disc transfers were shorter when imagining performing the task with a high performer than with a low performer. These findings suggest that MI is based on the simulation of one's own response code, and that the adaptation of MI to their partner's movements influences the MI of one's own movements.

Imitation-inhibition training can reduce the observation-inflation effect in face-to-face scenarios.

Observing others performing an action can lead to false memories of self-performance-the observation-inflation effect. Previous research has indicated that this phenomenon might impact the memory of actions in real-world interactions. However, whether direct observation without interaction can lead to observation inflation remains unclear. In Experiment 1, participants passively observed the experimenter performing actions live. In subsequent memory tests, they indeed reported false memories regarding their performances. Building on this, Experiment 2 investigated the causes of the observation-inflation effect induced by "real" actions. Participants underwent imitation-inhibition training with the individuals they observed previously. The results revealed that participants who completed imitation-inhibition training reported fewer false memories in memory tests than those who completed imitation training. These findings suggest that even passive observation of "real" actions can lead to observation inflation, and the simulation of others' actions by individuals may be a potential underlying cause of their occurrence in real-life situations.

Action observation perspective influences the effectiveness of combined action observation and motor imagery training for novices learning an Osoto Gari judo throw.

Combined action observation and motor imagery (AOMI) training improves motor skill performance, but limited research has investigated possible moderating factors for this intervention. This study examined the influence of action observation (AO) perspective on the effectiveness of AOMI training for novices learning a 'shadow' Osoto Gari judo throw. Thirty novice participants were randomly assigned to AOMI training that displayed egocentric footage (AOMIEGO) or allocentric footage (AOMIALLO) of the Osoto Gari, or Control training. A motor learning design incorporating pre-test (Day 1), acquisition (Days 2-6), post-test (Day 7), and retention-test (Day 14) was adopted. Motor skill performance, self-efficacy, and mental representation structures were recorded as measures of learning. There were mixed effects for motor skill performance across the three training conditions utilized in this study, with AOMIALLO training significantly reducing error scores for final right hip flexion angle and peak right ankle velocity compared to AOMIEGO training. Self-efficacy increased for all training conditions over time. Both AOMIEGO and AOMIALLO training led to improved functional changes in mental representation structures over time compared to Control training. The findings suggest AOMI training led to improved perceptual-cognitive scaffolding, irrespective of AO perspective, and offer some support for the use of AOMIALLO training to facilitate novice learning of complex, serial motor skills in sport.

Brain mechanisms discriminating enactive mental simulations of running and plogging.

Enactive cognition emphasizes co-constructive roles of humans and their environment in shaping cognitive processes. It is specifically engaged in the mental simulation of behaviors, enhancing the connection between perception and action. Here we investigated the core network of brain regions involved in enactive cognition as applied to mental simulations of physical exercise. We used a neuroimaging paradigm in which participants (N = 103) were required to project themselves running or plogging (running while picking-up litter) along an image-guided naturalistic trail. Using both univariate and multivariate brain imaging analyses, we find that a broad spectrum of brain activation discriminates between the mental simulation of plogging versus running. Critically, we show that self-reported ratings of daily life running engagement and the quality of mental simulation (how well participants were able to imagine themselves running) modulate the brain reactivity to plogging versus running. Finally, we undertook functional connectivity analyses centered on the insular cortex, which is a key region in the dynamic interplay between neurocognitive processes. This analysis revealed increased positive and negative patterns of insular-centered functional connectivity in the plogging condition (as compared to the running condition), thereby confirming the key role of the insular cortex in action simulation involving complex sets of mental mechanisms. Taken together, the present findings provide new insights into the brain networks involved in the enactive mental simulation of physical exercise.

Motor imagery in autism: a systematic review.

Introduction: Motor Imagery (MI) is when an individual imagines performing an action without physically executing that action and is thought to involve similar neural processes used for execution of physical movement. As motor coordination difficulties are common in autistic individuals it is possible that these may affect MI ability. The aim of this systematic review was to assess the current knowledge around MI ability in autistic individuals. Methods: A systematic search was conducted for articles published before September 2023, following PRISMA guidance. Search engines were PsycINFO, PubMed, Web of Science, Scopus, Wiley Online Library and PsyArXiv. Inclusion criteria included: (a) Original peer-reviewed and pre-print publications; (b) Autistic and a non-autistic group (c) Implicit or explicit imagery tasks (d) Behavioral, neurophysiological or self-rating measures, (e) Written in the English language. Exclusion criteria were (a) Articles only about MI or autism (b) Articles where the autism data is not presented separately (c) Articles on action observation, recognition or imitation only (d) Review articles. A narrative synthesis of the evidence was conducted. Results: Sixteen studies across fourteen articles were included. Tasks were divided into implicit (unconscious) or explicit (conscious) MI. The implicit tasks used either hand (6) or body (4) rotation tasks. Explicit tasks consisted of perspective taking tasks (3), a questionnaire (1) and explicit instructions to imagine performing a movement (2). A MI strategy was apparent for the hand rotation task in autistic children, although may have been more challenging. Evidence was mixed and inconclusive for the remaining task types due to the varied range of different tasks and, measures conducted and design limitations. Further limitations included a sex bias toward males and the hand rotation task only being conducted in children. Discussion: There is currently an incomplete understanding of MI ability in autistic individuals. The field would benefit from a battery of fully described implicit and explicit MI tasks, conducted across the same groups of autistic children and adults. Improved knowledge around MI in autistic individuals is important for understanding whether MI techniques may benefit motor coordination in some autistic people.

Guidelines for reporting action simulation studies (GRASS): Proposals to improve reporting of research in motor imagery and action observation.

Researchers from multiple disciplines have studied the simulation of actions through motor imagery, action observation, or their combination. Procedures used in these studies vary considerably between research groups, and no standardized approach to reporting experimental protocols has been proposed. This has led to under-reporting of critical details, impairing the assessment, replication, synthesis, and potential clinical translation of effects. We provide an overview of issues related to the reporting of information in action simulation studies, and discuss the benefits of standardized reporting. We propose a series of checklists that identify key details of research protocols to include when reporting action simulation studies. Each checklist comprises A) essential methodological details, B) essential details that are relevant to a specific mode of action simulation, and C) further points that may be useful on a case-by-case basis. We anticipate that the use of these guidelines will improve the understanding, reproduction, and synthesis of studies using action simulation, and enhance the translation of research using motor imagery and action observation to applied and clinical settings.

Emotion processes and perceptual control of action choice.

This editorial introduces an invited article by Andreas Eder on a new perceptual control theory of action choice, based on the comparison of real and simulated interoceptive signals generated by action alternatives. Eder extends the cognitive action-control framework, postulating a bi-directional connection between outcomes and actions by introducing "emotional feelings", defined as valued interoceptive signals from the body. An invited commentary by Agnes Moors compares this theory with her own goal-directed theory of action control. While agreeing on the central role of a control cycle and the goal-directed nature of emotional actions, Moors disagrees on the content of the representations involved in the control cycle and the nature of the feelings involved. A second commentary by Bob Bramson and Karin Roelofs discusses the issues of the distinction between perception control vs. action control, the need for biologically plausible implementation alternatives, and potential implications for psychopathology and clinical intervention. Finally, the potential relevance of predictive coding theory and the role of appraisal processes in emotion generation with respect to their bearing on action comparison and choice are discussed.

Eye movements during motor imagery and execution reveal different visuomotor control strategies in manual interception.

Previous research has investigated the degree of congruency in gaze metrics between action execution (AE) and motor imagery (MI) for similar manual tasks. Although eye movement dynamics seem to be limited to relatively simple actions toward static objects, there is little evidence of how gaze parameters change during imagery as a function of more dynamic spatial and temporal task demands. This study examined the similarities and differences in eye movements during AE and MI for an interception task. Twenty-four students were asked to either mentally simulate or physically intercept a moving target on a computer display. Smooth pursuit, saccades, and response time were compared between the two conditions. The results show that MI was characterized by higher smooth pursuit gain and duration while no meaningful differences were found in the other parameters. The findings indicate that eye movements during imagery are not simply a duplicate of what happens during actual performance. Instead, eye movements appear to vary as a function of the interaction between visuomotor control strategies and task demands.

The effects of combined action observation and motor imagery on corticospinal excitability and movement outcomes: Two meta-analyses.

Motor simulation interventions involving motor imagery (MI) and action observation (AO) have received considerable interest in the behavioral sciences. A growing body of research has focused on using AO and MI simultaneously, termed 'combined action observation and motor imagery' (AOMI). The current paper includes two meta-analyses that quantify changes in corticospinal excitability and motor skill performance for AOMI compared to AO, MI and control conditions. Specifically, the first meta-analysis collated and synthesized existing motor evoked potential (MEP) amplitude data from transcranial magnetic stimulation studies and the second meta-analysis collated and synthesized existing movement outcome data from behavioral studies. AOMI had a positive effect compared to control and AO but not MI conditions for both MEP amplitudes and movement outcomes. No methodological factors moderated the effects of AOMI, indicating a robust effect of AOMI across the two outcome variables. The results of the meta-analyses are discussed in relation to existing literature on motor simulation and skill acquisition, before providing viable directions for future research on this topic.

The action-sentence compatibility effect (ACE): Meta-analysis of a benchmark finding for embodiment.

The embodied account of language comprehension has been one of the most influential theoretical developments in the recent decades addressing the question how humans comprehend and represent language. To examine its assumptions, many studies have made use of behavioral paradigms involving basic compatibility effects. The action-sentence compatibility effect (ACE) is one of the most influential of these compatibility effects and is the most widely cited evidence for the embodied account of language comprehension. However, recently there have been difficulties in extending or even in reliably replicating the ACE. The conflicting findings concerning the ACE and its extensions lead to the discussion of whether the ACE is indeed a reliable effect. In a first step we conducted a meta-analysis using a random-effects model. This analysis revealed a small but significant effect size of the ACE. Furthermore, the task-parameter Delay occurred as a factor of interest in whether the ACE appears with positive or negative effect direction. A second meta-analytic approach (Fisher's method) supports these findings. Additionally, an analysis of publication bias suggests that there is bias in the ACE literature. In post-hoc analyses of the recent multi-lab investigation of the ACE (Morey et al., 2021), evidence for individual differences in the ACE was found. However, further analyses indicate that these differences are likely due to item-specific variability and the specific way in which items were assigned to conditions in the counterbalancing lists.

Imagining interceptions: Eye movements as an online indicator of covert motor processes during motor imagery.

The analysis of eye movements during motor imagery has been used to understand the influence of covert motor processes on visual-perceptual activity. There is evidence showing that gaze metrics seem to be affected by motor planning often dependent on the spatial and temporal characteristics of a task. However, previous research has focused on simulated actions toward static targets with limited empirical evidence of how eye movements change in more dynamic environments. The study examined the characteristics of eye movements during motor imagery for an interception task. Twenty-four participants were asked to track a moving target over a computer display and either mentally simulate an interception or rest. The results showed that smooth pursuit variables, such as duration and gain, were lower during motor imagery when compared to passive observation. These findings indicate that motor plans integrate visual-perceptual information based on task demands and that eye movements during imagery reflect such constraint.

Dissociable effects of acute versus cumulative violent video game exposure on the action simulation circuit in university students.

There is an ongoing debate as to whether violent video game exposure (VGE) has a negative impact on social functioning. This debate continues in part because of methodological concerns and the paucity of identifiable neurocognitive mechanisms. Also, little attention has been given to how specific personality characteristics may influence susceptibility to the purported effects. Using a combined experimental and cross-sectional approach, we examined the impact of VGE on action simulation as a function of trait coldheartedness in a sample of university students. Healthy adults played a violent or nonviolent version of Grand Theft Auto V before completing an fMRI measure of action simulation circuit (ASC) activity. Simulation-related activity was not significantly different between groups; however, greater overall activation was observed in left inferior frontal gyrus for those in the violent condition. Contrary to predictions, no evidence was observed that trait coldheartedness significantly interacts with violent gaming to influence ASC activation. However, prior cumulative VGE was negatively correlated with simulation-related activity in a subsection of the ASC. This study highlights a potential dissociation between the effects of acute versus cumulative violent gaming and may challenge assumptions that the directionality of effects for cross-sectional associations always mirror those of acute exposure.

Is motor activity the key to the observation-inflation effect? The role of action simulation.

Observing others performing an action can lead to false memories of self-performance - the observation-inflation effect. The action simulation hypothesis proposes that an action simulation caused by people's observation of an action is the key reason for this effect. Previous studies have inconsistent views of this hypothesis. In the present study, we re-examined the role of action simulation and discussed the key aspects of the mental processes associated with it. We examined the hypotheses that (a) the magnitude of the observation-inflation effect would decrease as the action simulation was impeded and (b) the magnitude of the observation-inflation effect would not be significantly different in conditions in which participants watched either a part of a video or a full video. The results are consistent with the hypotheses. This study provides strong evidence that action simulation influences the generation of observation-inflation effects and that the process is continuous and can refer to further action information.

Neurophysiological markers discriminate different forms of motor imagery during action observation.

The dual-action simulation hypothesis proposes that both an observed and an imagined action can be represented simultaneously in the observer's brain. These two sensorimotor streams would either merge or compete depending on their relative suitability for action planning. To test this hypothesis, three forms of combined action observation and motor imagery (AO + MI) instructions were used in this repeated-measures experiment. Participants observed index finger abduction-adduction movements while imagining the same action (congruent AO + MI), little finger abduction-adduction (coordinative AO + MI), or a static hand (conflicting AO + MI). Single-pulse transcranial magnetic stimulation was applied to the left primary motor cortex. The amplitude of motor evoked potential responses were recorded from both the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles of the right-hand while eye movements were tracked. When controlling for the influence of relevant eye movements, corticospinal excitability was facilitated relative to control conditions in the concurrently observed and imagined muscles for both congruent and coordinative AO + MI conditions. Eye-movement metrics and social validation data from post-experiment interviews provided insight into the attentional and cognitive mechanisms underlying these effects. The findings provide empirical support for the dual-action simulation hypothesis, indicating for the first time that it is possible to co-represent observed and imagined actions simultaneously.

Sensorimotor system engagement during ASL sign perception: An EEG study in deaf signers and hearing non-signers.

When a person observes someone else performing an action, the observer's sensorimotor cortex activates as if the observer is the one performing the action, a phenomenon known as action simulation. While this process has been well-established for basic (e.g., grasping) and complex (e.g., dancing) actions, it remains unknown if the framework of action simulation is applicable to visual languages such as American Sign Language (ASL). We conducted an EEG experiment with deaf signers and hearing non-signers to compare overall sensorimotor EEG between groups, and to test whether sensorimotor systems are differentially sensitive to signs that are produced with one hand ("1H") or two hands ("2H"). We predicted greater alpha and beta event-related desynchronization (previously correlated with action simulation) during the perception of 2H ASL signs compared to 1H ASL signs, due to greater demands on sensorimotor processing systems required for producing two-handed actions. We recorded EEG from both groups as they observed videos of ASL signs, half 1H and half 2H. Event-related spectral perturbations (ERSPs) in the alpha and beta ranges were computed for the two conditions at central electrode sites overlying the sensorimotor cortex. Sensorimotor EEG responses in both Hearing and Deaf groups were sensitive to the observed gross motor characteristics of the observed signs. We show for the first time that despite hearing non-signers showing overall more sensorimotor cortex involvement during sign observation, mirroring-related processes are in fact involved when deaf signers observe signs.

Assessing language-induced motor activity through Event Related Potentials and the Grip Force Sensor, an exploratory study.

The link between language processing and motor systems has been the focus of increasing interest to Cognitive Neuroscience. Some classical papers studying Event Related Potentials (ERPs) induced by linguistic stimuli have found differences in electrophysiological activity when comparing action and non-action words; more specifically, a bigger p200 for action words. On the other hand, a series of studies have validated the use of a grip force sensor (GFS) to measure language-induced motor activity during both isolated words and sentence listening, finding that action words induce an augmentation in the grip force around 250-300 ms after the onset of the stimulus. The purpose of the present study is to combine both techniques to assess if the p200 is related to the augmentation of the grip force measured by a GFS. We measured ERP and GFS changes elicited by listening to action and non-action words while maintaining an active grasping task. Our results show that both the p200 and the grip force around 300 ms are bigger for action words, compared to non-action. We also report a statistical correlation between these measures. To our knowledge, this is the first study where the electrophysiological activity and the changes in the grip force induced by auditory language processing are put together, opening new venues of interpretation for the sensorimotor interaction in language processing.

Sensorimotor characteristics of sign translations modulate EEG when deaf signers read English.

Bilingual individuals automatically translate written words from one language to another. While this process is established in spoken-language bilinguals, there is less known about its occurrence in deaf bilinguals who know signed and spoken languages. Since sign language uses motion and space to convey linguistic content, it is possible that action simulation in the brain's sensorimotor system plays a role in this process. We recorded EEG from deaf participants fluent in ASL as they read individual English words and found significant differences in alpha and beta EEG at central electrode sites during the reading of English words whose ASL translations use two hands, compared to English words whose ASL translations use one hand. Hearing non-signers did not show any differences between conditions. These results demonstrate the involvement of the sensorimotor system in cross-linguistic, cross-modal translation, and suggest that covert action simulation processes are involved when deaf signers read.

Neural correlates of action: Comparing meta-analyses of imagery, observation, and execution.

Several models propose Motor Imagery, Action Observation, and Movement Execution recruit the same brain regions. There is, however, no quantitative synthesis of the literature that directly compares their respective networks. Here we summarized data from neuroimaging experiments examining Motor Imagery (303 experiments, 4902 participants), Action Observation (595 experiments, 11,032 participants), and related control tasks involving Movement Execution (142 experiments, 2302 participants). Comparisons across these networks showed that Motor Imagery and Action Observation recruited similar premotor-parietal cortical networks. However, while Motor Imagery recruited a similar subcortical network to Movement Execution, Action Observation did not consistently recruit any subcortical areas. These data quantify and amend previous models of the similarities in the networks for Motor Imagery, Action Observation, and Movement Execution, while highlighting key differences in their recruitment of motor cortex, parietal cortex, and subcortical structures.

Group membership and racial bias modulate the temporal estimation of in-group/out-group body movements.

Social group categorization has been mainly studied in relation to ownership manipulations involving highly-salient multisensory cues. Here, we propose a novel paradigm that can implicitly activate the embodiment process in the presence of group affiliation information, whilst participants complete a task irrelevant to social categorization. Ethnically White participants watched videos of White- and Black-skinned models writing a proverb. The writing was interrupted 7, 4 or 1 s before completion. Participants were tasked with estimating the residual duration following interruption. A video showing only hand kinematic traces acted as a control condition. Residual duration estimates for out-group and control videos were significantly lower than those for in-group videos only for the longest duration. Moreover, stronger implicit racial bias was negatively correlated to estimates of residual duration for out-group videos. The underestimation bias for the out-group condition might be mediated by implicit embodiment, affective and attentional processes, and finalized to a rapid out-group categorization.

Curb Your Embodiment.

To explain how abstract concepts are grounded in sensory-motor experiences, several theories have been proposed. I will discuss two of these proposals, Conceptual Metaphor Theory and Situated Cognition, and argue why they do not fully explain grounding. A central idea in Conceptual Metaphor Theory is that image schemas ground abstract concepts in concrete experiences. Image schemas might themselves be abstractions, however, and therefore do not solve the grounding problem. Moreover, image schemas are too simple to explain the full richness of abstract concepts. Situated cognition might provide such richness. Research in our laboratory, however, has shown that even for concrete concepts, sensory-motor grounding is task dependent. Therefore, it is questionable whether abstract concepts can be significantly grounded in sensory-motor processing.