Motor contagion: the contribution of trajectory and end-points

Increased involuntary arm movement deviation when observing an incongruent human arm movement has been interpreted as a strong indicator of motor contagion. Here, we examined the contribution of trajectory and end-point information on motor contagion by altering congruence between the stimulus and arm movement. Participants performed cyclical horizontal arm movements whilst simultaneously observing a stimulus representing human arm movement. The stimuli comprised congruent horizontal movements or vertical movements featuring incongruent trajectory and end-points. A novel, third, stimulus comprised curvilinear movements featuring congruent end-points, but an incongruent trajectory. In Experiment 1, our dependent variables indicated increased motor contagion when observing the vertical compared to horizontal movement stimulus. There was even greater motor contagion in the curvilinear stimulus condition indicating an additive effect of an incongruent trajectory comprising congruent end-points. In Experiment 2, this additive effect was also present when facing perpendicular to the display, and thus with end-points represented as a product of the movement rather than an external spatial reference. Together, these findings support the theory of event coding (Hommel et al., Behav Brain Sci 24:849–878, 2001), and the prediction that increased motor contagion takes place when observed and executed actions share common features (i.e., movement end-points)

Atypical emotional anticipation in high-functioning autism

"Background: Understanding and anticipating others’ mental or emotional states relies on the processing of social cues, such as dynamic facial expressions. Individuals with high-functioning autism (HFA) may process these cues differently from individuals with typical development (TD) and purportedly use a ‘mechanistic’ rather than a ‘mentalistic’ approach, involving rule- and contingency-based interpretations of the stimuli. The study primarily aimed at examining whether the judgments of facial expressions made by individuals with TD and HFA would be similarly affected by the immediately preceding dynamic perceptual history of that face. A second aim was to explore possible differences in the mechanisms underpinning the perceptual judgments in the two groups. Methods: Twenty-two adults with HFA and with TD, matched for age, gender and IQ, were tested in three experiments in which dynamic, ‘ecologically valid’ offsets of happy and angry facial expressions were presented. Participants evaluated the expression depicted in the last frame of the video clip by using a 5-point scale ranging from slightly angry via neutral to slightly happy. Specific experimental manipulations prior to the final facial expression of the video clip allowed examining contributions of bottom-up mechanisms (sequential contrast/ context effects and representational momentum) and a top-down mechanism (emotional anticipation) to distortions in the perception of the final expression. Results: In experiment 1, the two groups showed a very similar perceptual bias for the final expression of joy-to-neutral and anger-to-neutral videos (overshoot bias). In experiment 2, a change in the actor’s identity during the clip removed the bias in the TD group, but not in the HFA group. In experiment 3, neutral-to-joy/anger-to-neutral sequences generated an undershoot bias (opposite to the overshoot) in the TD group, whereas no bias was observed in the HFA group. Conclusions: We argue that in TD individuals the perceptual judgments of other’s facial expressions were underpinned by an automatic emotional anticipation mechanism. In contrast, HFA individuals were primarily influenced by visual features, most notably the contrast between the start and end expressions, or pattern extrapolation. We critically discuss the proposition that automatic emotional anticipation may be induced by motor simulation of the perceived dynamic facial expressions and discuss its implications for autism.

The role of motor simulation in action perception: a neuropsychological case study

Research on embodied cognition stresses that bodily and motor processes constrain how we perceive others. Regarding action perception the most prominent hypothesis is that observed actions are matched to the observer's own motor representations. Previous findings demonstrate that the motor laws that constrain one's performance also constrain one's perception of others' actions. The present neuropsychological case study asked whether neurological impairments affect a person's performance and action perception in the same way. The results showed that patient DS, who suffers from a frontal brain lesion, not only ignored target size when performing movements but also when asked to judge whether others can perform the same movements. In other words DS showed the same violation of Fitts's law when performing and observing actions. These results further support the assumption of close perception action links and the assumption that these links recruit predictive mechanisms residing in the motor system

Grasping motor impairments in autism: Not action planning but movement execution is deficient

Contains fulltext : 125501.pdf (publisher's version ) (Closed access)Different views on the origin of deficits in action chaining in autism spectrum disorders (ASD) have been posited, ranging from functional impairments in action planning to internal models supporting motor control. Thirty-one children and adolescents with ASD and twenty-nine matched controls participated in a two-choice reach-to-grasp paradigm wherein participants received cueing information indicating either the object location or the required manner of grasping. A similar advantage for location cueing over grip cueing was found in both groups. Both accuracy and reaction times of the ASD group were indistinguishable from the control group. In contrast, movement times of the ASD group were significantly delayed in comparison with controls. These findings suggest that movement execution rather than action planning is deficient in ASD, and that deficits in action chaining derive from impairments in internal action models supporting action execution