Time course analyses confirm independence of automatic imitation and spatial compatibility effects

Automatic imitation has been used as a behavioural index of the functioning of the human mirror system (e.g. Brass, Bekkering, Wohlschlager, & Prinz, 2000; Heyes, Bird, Johnson, & Haggard, 2005; Kilner, Paulignan, & Blakemore, 2003). However, several papers have criticised the assumption that automatic imitation is mediated by the mirror system on the grounds that automatic imitation has been confounded with simple spatial compatibility (Aicken, Wilson, Williams, & Mon-Williams, 2007; Bertenthal, Longo, and Kosobud, 2006; Jansson, Wilson, Williams, & Mon-Williams, 2007). Two experiments are reported in which, in contrast with previous studies, automatic imitation was measured on both spatially compatible and spatially incompatible trials, and automatic imitation was shown to be present regardless of spatial compatibility. Additional features of the two experiments allowed measurement of the time courses of the automatic imitation and spatial compatibility effects both within and across trials. It was found that automatic imitation effects follow a different time course from spatial compatibility effects, providing further evidence for their independence and supporting the use of automatic imitation as a behavioural marker of mirror system functioning

Hand to mouth: automatic imitation across effector systems

The effector-specificity of automatic imitation was investigated using a stimulus-response compatibility (SRC) procedure in which participants were required to make an open or a close response with either their hand or their mouth. The correct response for each trial was indicated by a pair of letters, and each of these imperative stimuli was accompanied by task-irrelevant action images depicting a hand or mouth opening or closing. Relative to the response, the irrelevant stimulus was either movement compatible or movement incompatible, and either effector compatible or effector incompatible. A movement compatibility effect was observed for both hand and mouth responses. These movement compatibility effects were present when the irrelevant stimulus was effector compatible and when it was effector incompatible, but they were smaller when the irrelevant stimulus and response effectors were incompatible. These findings, which are consistent with the associative sequence learning model of imitation, indicate that automatic imitation is partially effector-specific, and therefore that the effector specificity of intentional and instructed imitation reflects, at least in part, the nature of the mechanisms that mediate visuomotor translation for imitation

Actions speak louder than words: comparing automatic imitation and verbal command

Automatic imitation – copying observed actions without intention – is known to occur, not only in neurological patients and those with developmental disorders, but also in healthy, typically-developing adults and children. Previous research has shown that a variety of actions are automatically imitated, and that automatic imitation promotes social affiliation and rapport. We assessed the power of automatic imitation by comparing it with the strength of the tendency to obey verbal commands. In a Stroop interference paradigm, the stimuli were compatible, incompatible and neutral compounds of hand postures and verbal commands. When imitative responses were required, the impact of irrelevant action images on responding to words was greater than the effect of irrelevant words on responding to actions. Control group performance showed that this asymmetry was not due to modality effects or differential salience of action and word stimuli. These results indicate that automatic imitation was more powerful than verbal command

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

Baby steps: investigating the development of perceptual-motor couplings in infancy

There are cells in our motor cortex that fire both when we perform and when we observe similar actions. It has been suggested that these perceptual-motor couplings in the brain develop through associative learning during correlated sensorimotor experience. Although studies with adult participants have provided support for this hypothesis, there is no direct evidence that associative learning also underlies the initial formation of perceptual–motor couplings in the developing brain. With the present study we addressed this question by manipulating infants’ opportunities to associate the visual and motor representation of a novel action, and by investigating how this influenced their sensorimotor cortex activation when they observed this action performed by others. Pre-walking 7–9-month-old infants performed stepping movements on an infant treadmill while they either observed their own real-time leg movements (Contingent group) or the previously recorded leg movements of another infant (Non-contingent control group). Infants in a second control group did not perform any steps and only received visual experience with the stepping actions. Before and after the training period we measured infants’ sensorimotor alpha suppression, as an index of sensorimotor cortex activation, while they watched videos of other infants’ stepping actions. While we did not find greater sensorimotor alpha suppression following training in the Contingent group as a whole, we nevertheless found that the strength of the visuomotor contingency experienced during training predicted the amount of sensorimotor alpha suppression at post-test in this group. We did not find any effects of motor experience alone. These results suggest that the development of perceptual–motor couplings in the infant brain is likely to be supported by associative learning during correlated visuomotor experience

Towards a Simplified Model to Describe Ozone Formation in Europe

Air pollution is a multi-faceted problem with a variety of pollutants released from a large number of different anthropogenic activities causing a multitude of environmental effects. Cost-effective strategies to reduce negative impacts of air pollution must take account of these complexities and consider the individual aspects of the air pollution problem simultaneously. Integrated assessment models provide a consistent framework for a systematic analysis of alternative strategies. One of such models, the RAINS (Regional Acidification Information and Simulation) model developed at IIASA, has been used as a scientific support tool for the international discussions on further reductions of emissions of sulfur dioxide in Europe, which led in 1994 to an agreement on the 'Second Sulfur Protocol'. The perceived success of this agreement motivated further work on extending model analysis to additional pollutants and effects. Elevated levels of tropospheric ozone are currently considered as one of the major air quality problems in Europe, calling for balanced reductions of emissions of nitrogen oxides and volatile organic compounds. A major obstacle for developing a practical integrated assessment model for ozone is the complexity and the size of most of the current models on atmospheric ozone formation. This paper tries to identify elements for potential model simplifications, which could contribute to the development of an operational European-scale ozone formation model. Such a simplified model would establish the core of an integrated assessment model for ozone formation, linking information on emissions and emission control costs with an assessment of their environmental impacts

Self-recognition of avatar motion: how do I know it's me?

When motion is isolated from form cues and viewed from third-person perspectives, individuals are able to recognize their own whole body movements better than those of friends. Because we rarely see our own bodies in motion from third-person viewpoints, this self-recognition advantage may indicate a contribution to perception from the motor system. Our first experiment provides evidence that recognition of self-produced and friends' motion dissociate, with only the latter showing sensitivity to orientation. Through the use of selectively disrupted avatar motion, our second experiment shows that self-recognition of facial motion is mediated by knowledge of the local temporal characteristics of one's own actions. Specifically, inverted self-recognition was unaffected by disruption of feature configurations and trajectories, but eliminated by temporal distortion. While actors lack third-person visual experience of their actions, they have a lifetime of proprioceptive, somatosensory, vestibular and first-person-visual experience. These sources of contingent feedback may provide actors with knowledge about the temporal properties of their actions, potentially supporting recognition of characteristic rhythmic variation when viewing self-produced motion. In contrast, the ability to recognize the motion signatures of familiar others may be dependent on configural topographic cues

Contextual Modulation of Mirror and Countermirror Sensorimotor Associations

Automatic imitation – the unintended copying of observed actions - is thought to be a behavioural product of the mirror neuron system (MNS). Evidence that the MNS develops through associative learning comes from previous research showing that automatic imitation is attenuated by counter-mirror training, in which the observation of one action is paired contingently with the execution of a different action. If the associative account of the MNS is correct, counter-mirror training should show context-specificity, because countermirror associations render action stimuli ambiguous, and ambiguity promotes contextual control. Two experiments are reported which confirm this prediction. In Experiment 1 we found less residual automatic imitation when human participants were tested in their counter-mirror training context. In Experiment 2, sensorimotor training where participants made action responses to novel abstract stimuli was insensitive to the same context manipulation, confirming that the former result was not a procedural artefact. Contextual modulation may enable the MNS to function effectively in spite of the fact that action observation often excites multiple conflicting MNS responses

The RAINS Optimization Module for the Clean Air For Europe (CAFE) Programme

In 2005 the European Commission developed the Thematic Strategy on Air Quality (COM (2005) 446). IIASA's TAP programme has been instrumental in preparing various emission scenarios for the development of the strategy, and the optimization module of RAINS has been used extensively in the exercise. In this report we document the mathematical formulation and methodological aspects of the optimization module of RAINS