Control Of Imitation Research Articles

Motor cognition in schizophrenia: Control of automatic imitation and mapping of action context are reduced

The ability to imitate is considered impaired in schizophrenia patients. This assumption, however, is based on heterogeneous studies mostly targeting voluntary imitation, e.g., pantomime. Studies on automatic imitation, however, and on underlying mechanisms of top-down inhibition of automatic imitation and contextual modulation in schizophrenia are highly limited. We employed two sensorimotor paradigms to examine imitation-inhibition and action context mapping in 37 schizophrenia patients and 36 matched controls. In the first experiment, participants performed finger lifts while observing a hand executing compatible or incompatible finger lifts from the third-person perspective. The compatibility or incompatibility of these finger lifts affected participants' reaction times (RTs). The comparison of between-condition RT differences shows a larger movement compatibility effect in schizophrenia than in controls. The second experiment involved finger lifts while watching a still hand, from the first-person perspective, with constrained fingers that either corresponded or did not correspond to the participants' response fingers. Here, schizophrenia patients showed a diminished RT slowing in corresponding constraint trials. While the former results provide evidence for an impaired control of imitation in patients with schizophrenia, the latter results indicate a reduced encoding of action context. In conclusion, this study provides the first evidence for deficits of top-down control of imitation and motor context processing in the same sample of schizophrenia patients.

Not So Automatic Imitation: Expectation of Incongruence Reduces Interference in Both Autism Spectrum Disorder and Typical Development.

Research has observed evidence for bothhypo-(supposedly due to a broken mirror neuron system) andhyper-(thought to be the result of deficits in adaptive control) imitation in autism spectrum disorder (ASD). This work sought to adjudicate between thesefindings using an automatic imitation (AI) paradigm with the novel manipulation of the need to engage adaptive control of imitation.Results demonstrated that ASD participants do not display a specific deficit in AI capability, are able to engage in proactive control of AI, and thatrelative to a well-matched effector condition, AI is not selectively associated with ASD symptom severity. These data cast doubt upon the notion of impairments in imitation or its control in ASD.

The inhibition of automatic imitation: A meta-analysis and synthesis of fMRI studies

Humans copy other people without their conscious awareness, a behaviour known as automatic imitation. Although automatic imitation forms a key part of daily social interactions, we do not copy other people indiscriminately. Instead, we control imitative tendencies by prioritising some actions and inhibiting others. To date, neuroimaging studies investigating the control of automatic imitation have produced inconsistent findings. Some studies suggest that imitation control relies on a domain-specific neural circuit related to social cognition (the theory-of-mind network). In contrast, other studies show engagement of a domain-general neural circuit that is engaged during a diverse range of cognitive control tasks (the multiple demand network). Given the inconsistency of prior findings, in the current paper we avoided problems associated with interpreting individual studies by performing a meta-analysis. To do so, we used a multi-level kernel density analysis to quantitatively identify consistent patterns of activation across functional magnetic resonance imaging studies investigating the control of imitation. Our results show clear and consistent evidence across studies that the control of automatic imitation is guided by brain regions in the multiple demand network including dorsolateral frontoparietal cortex. In contrast, there was only limited evidence that regions in the theory of mind network were engaged. Indeed, medial prefrontal cortex showed no consistent engagement and right temporoparietal junction engagement may reflect spatial rather than imitative control. As such, the current meta-analysis reinforces the role of domain-general control mechanisms and provides limited evidence in support of the role of domain-specific processes in regulating imitative tendencies. Consequently, neurocognitive models of imitation need updating to place more emphasis on domain-general control mechanisms, as well as to consider more complex organisational structures of control, which may involve contributions from multiple cognitive systems.

Disentangling Neural Sources of the Motor Interference Effect in High Functioning Autism: An EEG-Study.

The role of imitation in autism spectrum disorder (ASD) is controversial. Researchers have argued that deficient control of self- and other-related motor representations (self-other distinction) might explain imitation difficulties. In a recent EEG study, we showed that control of imitation relies on high-level as well as on low-level cognitive processes. Here, we aimed to further our insights into control of imitation deficits in ASD. We focused on congruency effects in the P3 (high-level), the N190 and the readiness potential (RP; low-level). We predicted smaller congruency effects within the P3 in the ASD group. However, we found differences in the RP and not in the P3-component. Thus, high-level self-other distinction centred on motor actions may be preserved in ASD, while impairments are reflected during motor preparation.

The imitation game: Effects of social cues on ‘imitation’ are domain-general in nature

Imitation has been hailed as ‘social glue’, facilitating rapport with others. Previous studies suggest that social cues modulate imitation but the mechanism of such modulation remains underspecified. Here we examine the locus, specificity, and neural basis of the social control of imitation. Social cues (group membership and eye gaze) were manipulated during an imitation task in which imitative and spatial compatibility could be measured independently. Participants were faster to perform compatible compared to incompatible movements in both spatial and imitative domains. However, only spatial compatibility was modulated by social cues: an interaction between group membership and eye gaze revealed more spatial compatibility for ingroup members with direct gaze and outgroup members with averted gaze. The fMRI data were consistent with this finding. Regions associated with the control of imitative responding (temporoparietal junction, inferior frontal gyrus) were more active during imitatively incompatible compared to imitatively compatible trials. However, this activity was not modulated by social cues. On the contrary, an interaction between group, gaze and spatial compatibility was found in the dorsolateral prefrontal cortex in a pattern consistent with reaction times. This region may be exerting control over the motor system to modulate response inhibition.

Self-other resonance, its control and prosocial inclinations: Brain-behavior relationships.

Humans seem to place a positive reward value on prosocial behavior. Evidence suggests that this prosocial inclination is driven by our reflexive tendency to share in the observed sensations, emotions and behavior of others, or "self-other resonance". In this study, we examine how neural correlates of self-other resonance relate to prosocial decision-making. Subjects performed two tasks while undergoing fMRI: observation of a human hand pierced by a needle, and observation and imitation of emotional facial expressions. Outside the scanner, subjects played the Dictator Game with players of low or high income (represented by neutral-expression headshots). Subjects' offers in the Dictator Game were correlated with activity in neural systems associated with self-other resonance and anticorrelated with activity in systems implicated in the control of pain, affect, and imitation. Functional connectivity between areas involved in self-other resonance and top-down control was negatively correlated with subjects' offers. This study suggests that the interaction between self-other resonance and top-down control processes are an important component of prosocial inclinations towards others, even when biological stimuli associated with self-other resonance are limited. These findings support a view of prosocial decision-making grounded in embodied cognition.

Task-dependent and distinct roles of the temporoparietal junction and inferior frontal cortex in the control of imitation.

The control of neurological networks supporting social cognition is crucially important for social interaction. In particular, the control of imitation is directly linked to interaction quality, with impairments associated with disorders characterized by social difficulties. Previous work suggests inferior frontal cortex (IFC) and the temporoparietal junction (TPJ) are involved in controlling imitation, but the functional roles of these areas remain unclear. Here, transcranial direct current stimulation (tDCS) was used to enhance cortical excitability at IFC and the TPJ prior to the completion of three tasks: (i) a naturalistic social interaction during which increased imitation is known to improve rapport, (ii) a choice reaction time task in which imitation needs to be inhibited for successful performance and (iii) a non-imitative control task. Relative to sham stimulation, stimulating IFC improved the context-dependent control of imitation—participants imitated more during the social interaction and less during the imitation inhibition task. In contrast, stimulating the TPJ reduced imitation in the inhibition task without affecting imitation during social interaction. Neither stimulation site affected the non-imitative control task. These data support a model in which IFC modulates imitation directly according to task demands, whereas TPJ controls task-appropriate shifts in attention toward representation of the self or the other, indirectly impacting upon imitation.

The control of automatic imitation based on bottom-up and top-down cues to animacy: insights from brain and behavior.

Humans automatically imitate other people's actions during social interactions, building rapport and social closeness in the process. Although the behavioral consequences and neural correlates of imitation have been studied extensively, little is known about the neural mechanisms that control imitative tendencies. For example, the degree to which an agent is perceived as human-like influences automatic imitation, but it is not known how perception of animacy influences brain circuits that control imitation. In the current fMRI study, we examined how the perception and belief of animacy influence the control of automatic imitation. Using an imitation-inhibition paradigm that involves suppressing the tendency to imitate an observed action, we manipulated both bottom-up (visual input) and top-down (belief) cues to animacy. Results show divergent patterns of behavioral and neural responses. Behavioral analyses show that automatic imitation is equivalent when one or both cues to animacy are present but reduces when both are absent. By contrast, right TPJ showed sensitivity to the presence of both animacy cues. Thus, we demonstrate that right TPJ is biologically tuned to control imitative tendencies when the observed agent both looks like and is believed to be human. The results suggest that right TPJ may be involved in a specialized capacity to control automatic imitation of human agents, rather than a universal process of conflict management, which would be more consistent with generalist theories of imitative control. Evidence for specialized neural circuitry that "controls" imitation offers new insight into developmental disorders that involve atypical processing of social information, such as autism spectrum disorders.

Neural systems for preparatory control of imitation.

Humans have an automatic tendency to imitate others. Previous studies on how we control these tendencies have focused on reactive mechanisms, where inhibition of imitation is implemented after seeing an action. This work suggests that reactive control of imitation draws on at least partially specialized mechanisms. Here, we examine preparatory imitation control, where advance information allows control processes to be employed before an action is observed. Drawing on dual route models from the spatial compatibility literature, we compare control processes using biological and non-biological stimuli to determine whether preparatory imitation control recruits specialized neural systems that are similar to those observed in reactive imitation control. Results indicate that preparatory control involves anterior prefrontal, dorsolateral prefrontal, posterior parietal and early visual cortices regardless of whether automatic responses are evoked by biological (imitative) or non-biological stimuli. These results indicate both that preparatory control of imitation uses general mechanisms, and that preparatory control of imitation draws on different neural systems from reactive imitation control. Based on the regions involved, we hypothesize that preparatory control is implemented through top-down attentional biasing of visual processing.

The Role of the Right Temporoparietal Junction in the Control of Imitation

Controlling neural representations of the self and other people is fundamental to social cognition. Brain imaging studies have implicated the right temporoparietal junction (rTPJ) in this ability, but causal evidence for its role is lacking. A debate is also ongoing regarding whether the control of, or switching between, self and other representations is a specialized or domain-general process: the rTPJ's well-established role in reorienting attention supports a domain-general process, but a role specific to social cognition has also been proposed. Neuronavigated repetitive transcranial magnetic stimulation was used to target the rTPJ (and a control mid-occipital site) during a task requiring participants to switch between representations of others' actions on both a social and a nonsocial level, by manipulating imitative and spatial compatibility simultaneously and independently. Both imitative and spatial compatibility effects were apparent on response times; however, the effect of imitative compatibility was significantly stronger, indicating less control of imitation, during stimulation of the rTPJ relative to the control site. This suggests that the rTPJ is involved in switching between self and other representations, and further, that this process may not be entirely domain general.

Enhancing Social Ability by Stimulating Right Temporoparietal Junction

The temporoparietal junction (TPJ) is a key node within the "social brain". Several studies suggest that the TPJ controls representations of the self or another individual across a variety of low-level (agency discrimination, visual perspective taking, control of imitation) and high-level (mentalizing, empathy) sociocognitive processes. We explored whether sociocognitive abilities relying on on-line control of self and other representations could be modulated with transcranial direct current stimulation (tDCS) of TPJ. Participants received excitatory (anodal), inhibitory (cathodal), or sham stimulation before completing three sociocognitive tasks. Anodal stimulation improved the on-line control of self-other representations elicited by the imitation and perspective-taking tasks while not affecting attribution of mental states during a self-referential task devoid of such a requirement. Our findings demonstrate the efficacy of tDCS to improve social cognition and highlight the potential for tDCS to be used as a tool to aid self-other processing in clinical populations.

Emotional Resonance Deficits in Autistic Children

According to some theories imitation, defined as an action resonance mechanism, is deficient in autism. In contrast, other theories (e.g., the "top down control of imitation" hypothesis) state that the problem is not in imitation per se but in the way social cues modulate imitative responses. In this study, 15 high-functioning children with autism and 15 matched controls were tested for their ability to imitate finger movements preceded by neutral and emotional facial expressions (primes) in a stimulus-response compatibility task. Hand movements performed after neutral expressions did not differ between the two groups (i.e., they both showed a normal imitative tendency). However, hand movements performed after emotional expressions significantly differed between the two populations, with controls, but not autistic spectrum disorder (ASD), showing enhanced imitation in the emotional condition. This study supports the view that, in ASD, imitation abilities are spared but they are not modulated according to the emotional and social context.

Shaking hands: Priming by social action effects

In a semi-naturalistic response-effect compatibility paradigm, participants were given the opportunity to learn that hand-shaking actions would be followed by social effects (human hand-shaking stimuli from a third-person perspective) or inanimate effects (block arrow stimuli). Relative to the actions, these effects appeared on the same or the opposite side of the screen (positional compatibility), and pointed towards or away from the response hand (directional compatibility). After learning, response times indicated a positional compatibility effect for both social and inanimate effects, but a directional compatibility effect occurred only for social action effects. These findings indicate that actions can be represented, not only by their effects on the inanimate world, but also by their effects on the actions of others. They are consistent with ideomotor theory, and with the view that actions are represented by bidirectional response-effect associations. They also have implications with respect to the origins and on-line control of imitation and the systems supporting imitation.

Resisting motor mimicry: Control of imitation involves processes central to social cognition in patients with frontal and temporo-parietal lesions

Perception and execution of actions share a common representational and neural substrate and thereby facilitate unintentional motor mimicry. Controlling automatic imitation is therefore a crucial requirement of such a “shared representational” system. Based on previous findings from neuroimaging, we suggest that resisting motor mimicry recruits the same underlying computational mechanisms also involved in higher-level social cognitive processing, such as self − other differentiation and the representation of mental states. The aim of the present study was to investigate on a behavioral level whether there is a functional association between the inhibition of imitation and tasks, assessing the understanding of mental states and of different perspectives of self and other. In a sample of neuropsychological patients with frontal lesions, a correlation between the ability for mental state attribution and the control of imitation was found, with a similar effect in the control group. Temporo-parietal lesioned patients showed a highly significant correlation between imitative control and visual and cognitive perspective-taking. Even after controlling for executive functions, the results remained significant, indicating the functional specificity of this relationship. These findings provide new insight into the functional processes underlying the control of shared representations and suggest a novel link between embodied and higher-level social cognition.

Associative sequence learning: the role of experience in the development of imitation and the mirror system.

A core requirement for imitation is a capacity to solve the correspondence problem; to map observed onto executed actions, even when observation and execution yield sensory inputs in different modalities and coordinate frames. Until recently, it was assumed that the human capacity to solve the correspondence problem is innate. However, it is now becoming apparent that, as predicted by the associative sequence learning model, experience, and especially sensorimotor experience, plays a critical role in the development of imitation. We review evidence from studies of non-human animals, children and adults, focusing on research in cognitive neuroscience that uses training and naturally occurring variations in expertise to examine the role of experience in the formation of the mirror system. The relevance of this research depends on the widely held assumption that the mirror system plays a causal role in generating imitative behaviour. We also report original data supporting this assumption. These data show that theta-burst transcranial magnetic stimulation of the inferior frontal gyrus, a classical mirror system area, disrupts automatic imitation of finger movements. We discuss the implications of the evidence reviewed for the evolution, development and intentional control of imitation.

Evolution, development and intentional control of imitation

Imitation is at the heart of social cognitive neuroscience. It is a neurocognitive process that bridges the gap between minds; powers cognitive and social development; promotes cooperation and well-being; and provides a channel of cultural inheritance. The papers in this theme issue review cutting-edge research on imitation and report original data using all of the principal methodologies, including comparative, developmental, cognitive-behavioural and neurological techniques. This paper introduces these interdisciplinary contributions and, proposing that the field currently has four inter-related foci--correspondence, control, cooperation and cultural inheritance--offers an overview of the state-of-the-art in research on the mechanisms and functions of imitation.

Discrimination and instructions as factors in the control of nonreinforced imitation

Three experiments were conducted to investigate factors controlling performance of nonreinforced verbal imitation. The first experiment investigated the discrimination hypothesis by systematically reducing the number of responses in the reinforced class. Results were inconsistent. Two of four children showed a significant reduction in nonreinforced responses though rates stayed high. The second and third experiments evaluated instructions on nonreinforced responses. Instructions to SAY the words were given only during the first session. Subsequent instructions not to say nonreinforced words resulted in reduced imitation, while instructions to “Do anything you want” resulted in high rates of nonreinforced imitation for both children in Experiment 2 and three of four children in Experiment 3.

Generalized imitation: The effects of experimenter absence, differential reinforcement, and stimulus complexity

The level of imitative behavior displayed by four preschool children was assessed during experimenter presence, experimenter absence, and under a differential reinforcement condition where only two of four responses were reinforced. Imitations were frequently performed during experimenter presence but were seldom observed when the experimenter was absent. Three of the four subjects imitated differentially under the reinforcement condition. However, the presence of the experimenter served to abolish this performance in two subjects. An attempt to add to the complexity of the stimulus situation by increasing the number and type of behaviors demonstrated to these two subjects, was not successful in maintaining nonreinforced imitations. The study indicates the need for a more precise definition of “generalized imitation” and emphasizes the importance of antecedent and setting conditions as factors in the multiple control of imitation.

THE SOCIAL CONTROL OF GENERALIZED IMITATION1

Instructions, discrimination procedures, and sources of reinforcement were manipulated in order to determine the bases for the maintained "non-reinforced" imitations observed in generalized imitation research. Six girls received imitation training from two experimenters. One experimenter modelled only reinforced responses; the other modelled only non-reinforced responses. The children imitated all responses when no reinforced alternative was available, even though results of choice procedures and special instructions clearly demonstrated that they discriminated reinforced from non-reinforced responses. Instructions not to perform non-reinforced imitations immediately eliminated these behaviors. It is suggested that social setting events may be largely responsible for generalized imitation.