Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Passive observation of traditional automated systems <s> Abstract Weinvestigated whether observation of actions reproduced in three-dimensional virtual reality would engage perceptual and visuomotor brain processes different from those induced by the observation of real hand actions. Participants were asked to passively observe grasping actions of geometrical objects made by a real hand or by hand reconstructions of different quality in 3D virtual reality as well as on a 2D TV screen. We found that only real actions in natural environment activated a visuospatial network including the right posterior parietal cortex. Observation of virtual-reality hand actions engaged prevalent visual perceptual processes within lateral and mesial occipital regions. Thus, only perception of actions in reality maps onto existing action representations, whereas virtual-reality conditions do not access the full motor knowledge available to the central nervous system. <s> BIB001 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Passive observation of traditional automated systems <s> Recent behavioural and neuroimaging studies have found that observation of human movement, but not of robotic movement, gives rise to visuomotor priming. This implies that the Fmirror neuron_ or Faction observation–execution matching_ system in the premotor and parietal cortices is entirely unresponsive to robotic movement. The present study investigated this hypothesis using an Fautomatic imitation_ stimulus–response compatibility procedure. Participants were required to perform a prespecified movement (e.g. opening their hand) on presentation of a human or robotic hand in the terminal posture of a compatible movement (opened) or an incompatible movement (closed). Both the human and the robotic stimuli elicited automatic imitation; the prespecified action was initiated faster when it was cued by the compatible movement stimulus than when it was cued by the incompatible movement stimulus. However, even when the human and robotic stimuli were of comparable size, colour and brightness, the human hand had a stronger effect on performance. These results suggest that effector shape is sufficient to allow the action observation–matching system to distinguish human from robotic movement. They also indicate, as one would expect if this system develops through learning, that to varying degrees both human and robotic action can be Fsimulated_ by the premotor and parietal cortices. D 2005 Elsevier B.V. All rights reserved. Theme: Neural basis of behaviour Topic: Cognition <s> BIB002 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Passive observation of traditional automated systems <s> In humans and monkeys the mirror neuron system transforms seen actions into our inner representation of these actions. Here we asked if this system responds also if we see an industrial robot perform similar actions. We localised the motor areas involved in the execution of hand actions, presented the same subjects blocks of movies of humans or robots perform a variety of actions. The mirror system was activated strongly by the sight of both human and robotic actions, with no significant differences between these two agents. Finally we observed that seeing a robot perform a single action repeatedly within a block failed to activate the mirror system. This latter finding suggests that previous studies may have failed to find mirror activations to robotic actions because of the repetitiveness of the presented actions. Our findings suggest that the mirror neuron system could contribute to the understanding of a wider range of actions than previously assumed, and that the goal of an action might be more important for mirror activations than the way in which the action is performed. <s> BIB003 </s> Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review <s> Passive observation of traditional automated systems <s> Abstract An impressive body of literature in the past 20 years has revealed a possible role played by cortical motor areas in action perception. One question that has been of interest is whether these areas are selectively tuned to process the actions of biological agents. However, no experiments directly testing the effects of the main characteristics identifying a biological agent (physical appearance and movement kinematics) on corticospinal excitability (CS) are present in literature. To fill this gap, we delivered single-pulse transcranial magnetic stimulation to the primary motor cortex and we recorded motor evoked potentials from contralateral hand muscles during observation of point-light-displays stimuli representing a hand having lost its physical appearance (Experiment 1) and kinematics characteristics (Experiment 2). Results showed that physical appearance, natural kinematics, and the possibility to identify the action behind the stimulus are not necessary conditions to modulate CS excitability during stimuli observation. We propose that the involvement of the motor system can be mandatory whenever the perceived movement, executed by a human, by an animal or by an object, is recognized as reproducible in its final outcome (e.g., position in space, direction of movement, posture of a body part, to-be-produced sound, specific interaction with an object, etc.), and that the peculiar relationship existing between others’ actions and the actions executed by the observer could just represent the extreme in which the motor system is able to almost perfectly reproduce the observed stimulus as it unfolds and, consequently, contribute to stimulus perception in the most efficient way. <s> BIB004
A reaction time study by BIB002 demonstrated that the action/observation matching system was sensitive to the observation of robotic gestures BIB002 . Indeed, when individuals were primed by the picture of a compatible hand gesture (e.g., an opened posture), they were faster to perform this action then compared to when they were primed by an incompatible hand posture (e.g., a close posture), both for human and robotic hands. Nonetheless, this compatibility effect was stronger with the human primes. At the cerebral level, BIB001 's showed that the predictive system was not activated during the observation of a non-humanized virtual hand (with 27 degrees of freedom) performing goal-directed actions, such as object grasping, even though the actions fitted a biological template BIB001 . In their study, the hand stimulus used was not a robotic arm strictly speaking but even so, it was visually close to a nonhumanized automated hand. However, it has also been brought to light that the predictive system could be activated during the observation of automaton-generated actions that did not follow biological motion laws BIB003 . In fact, in their fMRI study, Gazzola and her colleagues demonstrated that the mirror brain areas involved in predictive mechanisms were activated while individuals were looking at videos of a non-humanoid robotic arm that was performing non-biological simple and complex object-directed actions. In this study, participants were shown videos of an agent's arm reaching and grasping familiar objects or just performing non-goal-directed movements without any object. The agent's arm could be either a human arm with biological motion laws or a non-humanoid robotic arm with robotic motion laws. Thus, while the goal of the actions was the same, the way this goal was achieved clearly differed according to the effector's motion properties. The predictive system was similarly solicited during the human and the robotic actions suggesting that the kinematic properties of the action did not matter. Indeed, it has been hypothesized that when an observer is familiar with an action goal, deviations (from our own motor system) in kinematics can be passed over and it is still possible to elicit the observer's predictive system. Following this line of thought, the congruence between a represented goal and an observed goal is enough to trigger the predictive system activation BIB003 . On another side, a TMS study by BIB004 showed the involvement of the motor system during the passive observation of simplistic hand action representations (using a point light display), both when the kinematics were biological and non-biological, with no difference between the two conditions, and even though the stimuli were not perceived as hands BIB004 .