Automatic imitation of intransitive actions

Previous research has indicated a potential discontinuity between monkey and human ventral premotor-parietal mirror systems, namely that monkey mirror systems process only transitive (object-directed) actions, whereas human mirror systems may also process intransitive (non-object-directed) actions. The present study investigated this discontinuity by seeking evidence of automatic imitation of intransitive actions--hand opening and closing--in humans using a simple reaction time (RT), stimulus-response compatibility paradigm. Left-right and up-down spatial compatibility were controlled by ensuring that stimuli were presented and responses executed in orthogonal planes, and automatic imitation was isolated from simple and complex orthogonal spatial compatibility by varying the anatomical identity of the stimulus hand and response hemispace, respectively. In all conditions, action compatible responding was faster than action incompatible responding, and no effects of spatial compatibility were observed. This experiment therefore provides evidence of automatic imitation of intransitive actions, and support for the hypothesis that human and monkey mirror systems differ with respect to the processing of intransitive actions.     

Automatic imitation and spatial compatibility in a key-pressing task

Automatic imitation has been often confounded with spatial compatibility effects. Heyes (2011) called attention to this confound, and proposed some criteria which must be satisfied before these effects could be unequivocally taken to be an index of the functioning of the human mirror system. Evidence satisfying such criteria has been reported by Catmur and Heyes (2011), using a relatively unfamiliar finger abduction movement. However, because many previous studies relied on more familiar actions, we aimed at testing whether analogous effects could be obtained with a more practiced key-pressing task. In Experiment 1, we used anatomical controls (i.e., views of right vs. left hands) under conditions affording mirror imitation, and showed that spatial compatibility masked the effects of automatic imitation. Experiment 2 used rotated conditions to control for this spatial-anatomical confound, and it showed unequivocal effects of automatic imitation, which were obtained regardless of its relation to the spatial stimulus-response mapping. These results cast some doubts on the interpretation of previous reports relying exclusively on scenes presented from a mirror perspective, and suggest the convenience of using both rotated scenes and anatomical controls in order to assess automatic imitation.     

Automatic imitation of biomechanically possible and impossible actions: effects of priming movements versus goals

Recent behavioral, neuroimaging, and neurophysiological research suggests a common representational code mediating the observation and execution of actions; yet, the nature of this representational code is not well understood. The authors address this question by investigating (a) whether this observation-execution matching system (or mirror system) codes both the constituent movements of an action as well as its goal and (b) how such sensitivity is influenced by top-down effects of instructions. The authors tested the automatic imitation of observed finger actions while manipulating whether the movements were biomechanically possible or impossible, but holding the goal constant. When no mention was made of this difference (Experiment 1), comparable automatic imitation was elicited from possible and impossible actions, suggesting that the actions had been coded at the level of the goal. When attention was drawn to this difference (Experiment 2), however, only possible movements elicited automatic imitation. This sensitivity was specific to imitation, not affecting spatial stimulus-response compatibility (Experiment 3). These results suggest that automatic imitation is modulated by top-down influences, coding actions in terms of both movements and goals depending on the focus of attention.     

Prosocial consequences of imitation

Research has shown that helping behavior can be primed easily. However, helping decreases significantly in the presence of inhibition cues, signaling high costs for the executor. On the other hand, multiple studies demonstrated that helping behavior increases after being mimicked. The present study investigated whether imitation still increases helping when more substantial costs are involved. Helping behavior was operationalized as the willingness to accompany the confederate on a 15-20 minute walk to the train station. Results show that even in the face of these high costs, participants who were mimicked agreed more often to help the confederate than participants who were anti-mimicked. These findings suggest that mimicry not only makes people more helpful when it comes to small favors, but also allows them to ignore the substantial costs possibly involved in helping others.     

Generalized imitation in infants

Effects of modeling and contingent praise on infant's motor response topographies were experimentally analyzed. Three 10-month-old male infants and their mothers participated in 20-min. experimental sessions two to four times a week for 2 to 7 months. During each session a mother presented her infant with 15 toys randomly selected from a pool of 45. The infant was allowed to play with each toy for 1 min. During treatment the mother modeled prescribed responses with each toy, and during 10 training trials per session, she praised her infant if he emitted topographically similar responses. Interspersed among training trials were five probe trials for which praise was seldom available. All three infants showed systematic increases in the targeted training and probe response topographies following the introduction of the modeling and praise treatment procedure. Thus, responding during probes demonstrated generalized imitation with infants, a new and developmentally important population.     

Processes and products of imitation: Additional evidence that imitation is progressive

The spontaneous verbal interactions of two children and their babysitter were recorded over the period of half a year. The children were males, from middle-class backgrounds, and 2 years old at the beginning of the observation period. Imitated utterances were found to surpass quantitatively spontaneous ones on the dimensions of grammatical and semantic complexity. With few exceptions, new structures appeared first in imitative utterances and only later in spontaneous ones. Both the higher complexity and the prior appearance of new constructions in imitative utterances suggest that imitation fulfilled a progressive function for the observed children.     

Arousal and imitation of aggression

Forty boys, aged 5 and 6 years, viewed either an aggressive or nonaggressive film and were tested for imitation of the behavior displayed in the film. On the next day, before being tested again for imitation of the film, half the subjects in each film condition engaged in arousing play with the experimenter, and half in quiet play. According to the prediction, those aroused on the second day displayed more imitative behavior than those not aroused, regardless of which film they had seen. The results are discussed in terms of arousal as a performance variable in social learning.Thanks are due to Louis Morris, for advice and suggestions, and to Jeffrey Cohen, for assistance in data collection. This research was facilitated by funds from the Tulane University Council on Research.     

An analysis of generalized imitation

An experimenter presented English words to three intermediate-level children and reinforced accurate imitation of these words. The experimenter also presented novel Spanish words, but the imitation of these words was never experimentally reinforced. One subject quickly ceased performing non-reinforced imitative responses. The other two subjects were exposed to a series of conditions designed to facilitate discrimination. Upon observing the first subject for one session they immediately ceased imitating Spanish demonstrations. For all three subjects, when reinforcement was delivered for responses other than imitation, all imitative responses eventually ceased. When reinforcement was reintroduced for English imitations there was an immediate resumption of such responses to their previous 100% level. The occurrence of non-reinforced imitations in this and previous studies was discussed as being a function of one or combination of four variables: (1) similarity acquiring conditioned reinforcing properties, or (2) instructional, (3) coincidental, or (4) conditional stimulus generalization.     

Language and imitation in development

Noting the central role accorded imitation in the origins of symbolic functioning, language development, and identity formation, as well as its relationship to aspects of individuation, the authors have reviewed the problem of imitation from both cognitive developmental and psychoanalytic perspectives. They have specifically delineated piagetian views regarding the origins of imitation and traced its relationship to the emergence of language, while attempting to clarify various psychoanalytic formulations on this topic. This dual theoretical perspective is then reconsidered within the framework of the current empirical infancy literature. Pathological sequelae of imitation are also reviewed in relation to their impact upon ego formation and the process of socialization. Tracing a cognitive developmental line, the authors then discuss the relationship between imitation and the emergence of language; language is also considered as an important vehicle of communication which furthers and enhances ego development and object relations. The authors conclude with a partial integration of piagetian and psychoanalytic hypotheses regarding imitation and identity formation with the aim of stimulating further discussion on this topic.     

Causes and consequences of imitation

Recent behavioural and neuroscientific research concerning imitation has revealed evidence of experience-dependent imitation in chimpanzees and birds, wide ranging imitation deficits in autism, and unintentional imitation in adult humans. This review examines these findings and also evaluates evidence of neonatal imitation and intentional imitation in infancy, and evidence suggesting that the left inferior frontal gyrus is specialized for imitation. At the theoretical level, the empirical findings support the view that the perceptual-motor translation that is a unique and defining property of imitation depends primarily on direct links between sensory and motor representations established through correlated experience of observing movements and carrying them out.     

Multiple imitation mechanisms in children

Four studies using a computerized paradigm investigated whether children's imitation performance is content-specific and to what extent dependent on other cognitive processes such as trial-and-error learning, recall, and observational learning. Experiment 1 showed that 3-year-olds could successfully imitate what we call novel cognitive rules (e.g., first → second → third), which involved responding to 3 different pictures whose spatial configuration varied randomly from trial to trial. However, these same children failed to imitate what we call novel motor-spatial rules (e.g., up → down → right), which involved responding to 3 identical pictures that remained in a fixed spatial configuration from trial to trial. Experiment 2 showed that this dissociation was not due to a general difficulty in encoding motor-spatial content, as children successfully recalled, following a 30-s delay, a new motor-spatial sequence that had been learned by trial and error. Experiment 3 replicated these results and further demonstrated that 3-year-olds can infer a novel motor-spatial sequence following observation of a partially correct and partially incorrect response-a dissociation between imitation and observational learning (or emulation learning). Finally, Experiment 4 presented 3-year-olds with "familiar" motor-spatial sequences that involved making a linear response (e.g., left → middle → right) as well as "novel" motor-spatial sequences (e.g., right → up → down) used in Experiments 1-3 that were nonlinear and always involved a change in direction. Children had no difficulty imitating familiar motor-spatial sequences but again failed to imitate novel motor-spatial sequences. These results suggest that there may be multiple, dissociable imitation learning mechanisms that are content-specific. More importantly, the development of these imitation systems appears to be independent of the operations of other cognitive systems, including trial and error learning, recall, and observational learning.     

Conversational role influences speech imitation

This study assessed the impact of a conscious imitation goal on phonetic convergence during conversational interaction. Twelve pairs of unacquainted talkers participated in a conversational task designed to elicit between-talker repetitions of the same lexical items. To assess the degree to which the talkers exhibited phonetic convergence during the conversational task, these repetitions were used to elicit perceptual similarity judgments provided by separate sets of listeners. In addition, perceptual measures of phonetic convergence were compared with measures of articulation rates and vowel formants. The sex of the pair of talkers and a talker's role influenced the degree of phonetic convergence, and perceptual judgments of phonetic convergence were not consistently related to individual acoustic-phonetic attributes. Therefore, even with a conscious imitative goal, situational factors were shown to retain a strong influence on phonetic form in conversational interaction.     

Social attitudes modulate automatic imitation

In naturalistic interpersonal settings, mimicry or “automatic imitation” generates liking, affiliation, cooperation and other positive social attitudes. The purpose of this study was to find out whether the relationship between social attitudes and mimicry is bidirectional: Do social attitudes have a direct and specific effect on mimicry? Participants were primed with pro-social, neutral or anti-social words in a scrambled sentence task. They were then tested for mimicry using a stimulus-response compatibility procedure. In this procedure, participants were required to perform a pre-specified movement (e.g. opening their hand) on presentation of a compatible (open) or incompatible (close) hand movement. Reaction time data were collected using electromyography (EMG) and the magnitude of the mimicry/automatic imitation effect was calculated by subtracting reaction times on compatible trials from those on incompatible trials. Pro-social priming produced a larger automatic imitation effect than anti-social priming, indicating that the relationship between mimicry and social attitudes is bidirectional, and that social attitudes have a direct and specific effect on the tendency to imitate behavior without intention or conscious awareness.     

The social control of generalized imitation

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.     

Toddlers' responsive imitation predicts preschool-age conscience

Imitation has long been considered a mechanism for the development of conscience. Despite the central role of imitation in theories of moral internalization, the prediction from imitation to moral behavior has not been tested using an individual differences approach. In a longitudinal design, we examined whether individual differences in toddlers' responsive imitation predict preschool-age conscience. Mothers modeled actions for their children to imitate, and both matching behavior and motivation were observed at 14 and 22 months of age. We also measured preschool conscience by observing children's internalized conduct and guilt at ages 33 and 45 months. Imitation measures consistently predicted conscience variables. These relations were strengthened by aggregation across measures and times of assessment. Motivation and matching behavior each contributed independent variance in predicting preschool-age conscience. Results are consistent with the claim that responsive imitation reflects a general receptive stance to parents' guidance, and with both neopsychoanalytic and social cognitive views of imitation's importance in early moral development.     

Vocal imitation between mothers and infants

The aim of the present mixed cross-sectional and longitudinal study was to observe and describe some aspects of vocal imitation in natural mother-infant interaction. Specifically, maternal imitation of infant utterances was observed in relation to the imitative modeling, mirrored equivalence, and social guided learning models of infant speech development. Nine mother-infant dyads were audio-video recorded. Infants were recruited at different ages between 6 and 11 months and followed for 3 months, providing a quasi-longitudinal series of data from 6 through 14 months of age. It was observed that maternal imitation was more frequent than infant imitation even though vocal imitation was a rare maternal response. Importantly, mothers used a range of contingent and noncontingent vocal responses in interaction with their infants. Mothers responded to three-quarters of their infant's vocalizations, including speech-like and less mature vocalization types. The infants’ phonetic repertoire expanded with age. Overall, the findings are most consistent with the social guided learning approach. Infants rarely imitated their mothers, suggests a creative self-motivated learning mechanism that requires further investigation.     

The social context of imitation in infancy

Infants increasingly generalize deferred imitation across environmental contexts between 6 and 18 months of age. In three experiments with 126 6-, 9-, 12-, 15-, and 18-month-olds, we examined the role of the social context in deferred imitation. One experimenter demonstrated target actions on a hand puppet, and a second experimenter tested imitation 24h later. When the second experimenter was novel, infants did not exhibit deferred imitation at any age; when infants were preexposed to the second experimenter, all of them did. Imitating immediately after the demonstration also facilitated deferred imitation in a novel social context at all ages but 6 months. Infants' pervasive failure to exhibit deferred imitation in a novel social context may reflect evolutionary selection pressures that favored conservative behavior in social animals.