In this paper, I make a case for the modularity of the motor system. I start where many do in discussions of modularity, by considering the extent to which the motor system is cognitively penetrable, i.e., the extent to which its processing and outputs are causally influenced, in a semantically coherent way, by states of central cognition. I present some empirical findings from a range of sensorimotor adaptation studies that strongly suggest that there are limits to (...) such influence under certain conditions. These results cry out for an explanation. In the remainder of the paper, I provide one: The motor system is cognitively penetrable, but nonetheless modular along broadly Fodorian lines, insofar as it is informationally encapsulated. This means that its access is limited to its own proprietary database in computing its function from input to output, which does not include the information stored in central cognition. I then offer a model of action control, from distal intention to action outcomes, that further helps to illustrate this picture and can accommodate the target empirical findings. (shrink)

Largely aided by the neurological discovery of so-called “ mirror neurons,” the attention to motor activity during action observation has exploded over the last two decades. The idea that we internally “ mirror ” the actions of others has led to a new strand of implicit simulation theories of action understanding[1][2]. The basic idea of this sort of simulation theory is that we, via an automatic covert activation of our own action representations, can understand the action and possibly the (...) goal and/or intentions of the observed agent. In this way motor “simulation” is seen as the basis for low-level “mind-reading”; i.e. for the ascription of goals and intentional mental states to others. The thought is that one, through mirroring simulations, can get beyond the observable behaviour to the hidden minds of others. I am questioning the idea of an exclusively “mirroring” role of the motor system in social perception, which is tacitly assumed in this sort of simulation theories. Is motor activity during action observation really primarily a simulation, a detailed “echo” of the others action? My point is not that we never simulate what we observe, but rather to question whether such processes are representative of the overall motor contribution to social cognition. More and more studies on the functional properties of mirror neurons and motor facilitation during perception points to a more complex role of the motor system in action perception. Recently, several proposals have been made attempting to reinterpret and critique the function of motor activity in social situations. I shall here briefly touch on a few of these and sketch parts of my own alternative “social affordance” hypothesis of the sensorimotor contribution to social perception. By way of these analyses I highlight how traditional discussions are marred by problematic theoretical assumptions. It seems to me that we need a thorough reinterpretation not just of mirror neurons and mirroring, but also of what we take motor and social cognition to be. In my view the details of the sensorimotor findings underline the need to move beyond the simplistic idea of the motor system as a unitary output system. In terms of social cognition I question the traditional focus on hidden mental states. I suggest that the motor contribution might have more to do with understanding the process of how others choose their actions, navigate the world and relate to others than with simulating specific actual actions or mental states. I conclude that low-level simulation theories, which see the motor role in social perception as passive “mirroring,” are faced with serious empirical challenges, and that the motor system serve a much more proactive and complex cognitive role in social perception and interaction than previously thought. But my claim is also that many empirical tensions have slipped out of focus due to entrenched theoretical assumptions. Narrow theoretical expectations have marked not only the interpretations but the research itself and I propose that we are in dire need of more studies of actual contextual and interactive social perception. (shrink)

How do we know that our own actions belong to us? How are we able to distinguish self-generated sensory events from those that arise externally? In this paper, I will briefly discuss experiments that were designed to investigate these questions. In particularly, I will review psychophysical and neuroimaging studies that have investigated how we recognise the consequences of our own actions, and why patients with delusions of control confuse self-produced and externally produced actions and sensations. Studies investigating the failure of (...) this 'self-monitoring' mechanism in patients with delusions of control will be discussed in the context of the hypothesis that overactivity in the parietal cortex and the cerebellum contribute to the misattribution of an action to an external source (). (shrink)

Extrapersonal frames of reference for aimed movements are representationally convenient. They may, however, carry associated costs when the movement is executed in terms of the complex coordination of multiple joints they require. Studies that have measured both fingertip and joint paths suggest the motor systems may seek a compromise between simplicity of extrapersonal spatial representation and computational simplicity of multi-joint execution.

How do we know that our own actions belong to us? How are we able to distinguish self-generated sensory events from those that arise externally? In this paper, I will briefly discuss experiments that were designed to investigate these questions. In particularly, I will review psychophysical and neuroimaging studies that have investigated how we recognise the consequences of our own actions, and why patients with delusions of control confuse self-produced and externally produced actions and sensations. Studies investigating the failure of (...) this 'self-monitoring' mechanism in patients with delusions of control will be discussed in the context of the hypothesis that overactivity in the parietal cortex and the cerebellum contribute to the misattribution of an action to an external source (). (shrink)

Concepts are the elementary units of reason and linguistic meaning. They are conventional and relatively stable. As such, they must somehow be the result of neural activity in the brain. The questions are: Where? and How? A common philosophical position is that all concepts—even concepts about action and perception—are symbolic and abstract, and therefore must be implemented outside the brain’s sensory-motor system. We will argue against this position using (1) neuroscientific evidence; (2) results from neural computation; and (3) (...) results about the nature of concepts from cognitive linguistics. We will propose that the sensory-motor system has the right kind of structure to characterise both sensory-motor and more abstract concepts. Central to this picture are the neural theory of language and the theory of cogs, according to which, brain structures in the sensory-motor regions are exploited to characterise the so-called “abstract” concepts that constitute the meanings of grammatical constructions and general inference patterns. (shrink)

This commentary focuses on issues related to Glover's suppositions regarding the information available to the on-line control system and the behavioral consequences of (visual) information disruption. According to the author, a “highly accurate,” yet temporally unstable, visual representation of peripersonal space is available for real-time trajectory corrections. However, no direct evidence is currently available to support the position.

The present study evaluates the cognitive representation of a kicking movement performed by a human and a humanoid robot, and how they are represented in experts and novices of soccer and robotics, respectively. To learn about the expertise-dependent development of memory structures, we compared the representation structures of soccer experts and robot experts concerning a human and humanoid robot kicking movement. We found different cognitive representation structures for both expertise groups under two different motor performance conditions . In general, (...) the expertise relies on the perceptual-motor knowledge of the human motor system. Thus, the soccer experts’ cognitive representation of the humanoid robot movement is dominated by their representation of the corresponding human movement. Additionally, our results suggest that robot experts, in contrast to soccer experts, access functional features of the technical system of the humanoid robot in addition to their perceptual-motor knowledge about the human motor system. Thus, their perceptual-motor and neuro-functional machine representation are integrated into a cognitive representation of the humanoid robot movement. (shrink)

Zajonc and Markus published a chapter in 1984 that proposed solutions to the difficult problem of modeling interactions between cognition and emotion. The most radical of their proposals was the importance of the motor system in information processing. These initial preoccupations, when wedded with the vascular theory of emotional efference (VTEE), propelled theory and research about how the face works to control emotion and to control interpersonal interaction. We discuss the development of Bob’s thinking about facial expression—facial efference (...) is the term he preferred—as he moved toward predictions that sounded radical at the time, and which these days sound like precursors to advances in neuroscience and psychology subsumed under the term “embodied cognition.”. (shrink)

Embodied cognition theory posits that concept representations inherently rely on sensorimotor experiences that accompany their acquisitions. This is well established through concrete concepts. However, it is debatable whether representations of abstract concepts are based on sensorimotor representations. This study investigated the causal role of associated motor experiences that accompany concept acquisition in the involvement of the motor system in the abstract verb processing. Through two experiments, we examined the action–sentence compatibility effect, in the test phase after an (...) increase in motor features during the learning phase for abstract verbs with low motor features or novel words with no conceptual features at all. After associated motor experiences were added in the word learning phase, action–sentence compatibility effect was found in the semantic processing tasks during the test phase for abstract verbs and novel words. This was lacking in the word font color judgment task requiring no semantic processing. Coupled with our previous study, these findings suggest that motor features formed during word learning could causally affect embodiment in the motor system for abstract verbs, and reactivation of motor experiences in abstract verb processing depends on a given task’s demands. Our study supports the view that conceptual representations, even abstract concepts, can be grounded in sensorimotor experiences. (shrink)

This paper proposes an adaptive neural network control approach for a direct-current system with full state constraints. To guarantee that state constraints always remain in the asymmetric time-varying constraint regions, the asymmetric time-varying Barrier Lyapunov Function is employed to structure an adaptive NN controller. As we all know that the constant constraint is only a special case of the time-varying constraint, hence, the proposed control method is more general for dealing with constraint problem as compared with the existing works (...) on DC systems. As far as we know, this system is the first studied situations with time-varying constraints. Using Lyapunov analysis, all signals in the closed-loop system are proved to be bounded and the constraints are not violated. In this paper, the effectiveness of the control method is demonstrated by simulation results. (shrink)

Glover's planning–control model is based on his finding that visual illusions exert a larger effect in early phases than in late phases of a movement. But evidence for this dynamic illusion effect is weak, because: (a) it appears difficult to replicate; (b) Glover overestimates the accuracy of his results; and (c) he seems to underestimate the illusion effect at late phases.

Current models of speech motor control rely on either trajectory-based control (DIVA, GEPPETO, ACT) or a dynamical systems approach based on feedback control (Task Dynamics, FACTS). While both approaches have provided insights into the speech motor system, it is difficult to connect these findings across models given the distinct theoretical and computational bases of the two approaches. We propose a new extension of the most widely used dynamical systems approach, Task Dynamics, that incorporates many of the strengths (...) of trajectory-based approaches, providing a way to bridge the theoretical divide between what have been two separate approaches to understanding speech motor control. The Task Dynamics (TD) model posits that speech gestures are governed by point attractor dynamics consistent with a critically damped harmonic oscillator. Kinematic trajectories associated with such gestures should therefore be consistent with a second-order dynamical system, possibly modified by blending with temporally overlapping gestures or altering oscillator parameters. This account of observed kinematics is powerful and theoretically appealing, but may be insufficient to account for deviations from predicted kinematics – i.e., changes produced in response to some external perturbations to the jaw, changes in control during acquisition and development, or effects of word/syllable frequency. Optimization, such as would be needed to minimize articulatory effort, is also incompatible with the current TD model, though the idea that the speech production systems economizes effort has a long history and, importantly, also plays a critical role in current theories of domain-general human motor control. To address these issues, we use Dynamic Movement Primitives (DMPs) to expand a dynamical systems framework for speech motor control to allow modification of kinematic trajectories by incorporating a simple, learnable forcing term into existing point attractor dynamics. We show that integration of DMPs with task- based point-attractor dynamics enhances the potential explanatory power of TD in a number of critical ways, including the ability to account for external forces in planning and optimizing both kinematic and dynamic movement costs. At the same time, this approach preserves the successes of Task Dynamics in handling multi-gesture planning and coordination. (shrink)

The authors present the conceptual and system-theoretical model of human motor behaviour. The main assumption is that movement is the only observable manifestation of all psychical processes, thus, it is the only phenomenon enabling the creation of hypotheses concerning the psychological conditioning of human behaviour. They pointed to the fact that in the field of biology, and all the more, in psychology, mathematical descriptions are hardly eligible. In this respect, a system-theoretical approach seems to be appropriate. The (...) authors present two systems: information processing modalities in the human mind, based on Nikolai Bernstein’s theory, and the series of processes from stimuli reception to motor response execution. Both these sub-systems make up a super-system. Its simplified graphical representation may be termed “Column Diagram.” The authors analyse the functioning of this super-system in various intellectual-motor purposeful operations. The system-theoretical perspective enables clear categorisation of various human motor operations, their “driving” mechanisms, internal patterns, and their superficial physical and/or mathematical “appearance.” The stream of consciousness in a human motor operation joins the various psychological constructs, which are reception, perception, attention, motivation, intellect, memory, etc., into one coherent, inseparable system. (shrink)

The whole human body, the entire motor system including facial expressions and bodily gestures, is subject not just to emotions, but also abstract thought. Meaning, both emotional and cognitive, is grounded within the motor dimension. By implication, no meaningful philosophy of time can neglect the aspect of motor imagery.

The representational dynamics of the brain is a subsymbolic process, and it has to be conceived as an "agent-free" type of dynamical self-organization. However, in generating a coherent internal world-model, the brain decomposes target space in a certain way. In doing so, it defines an "ontology": to have an ontology is to interpret a world. In this paper we argue that the brain, viewed as a representational system aimed at interpreting the world, possesses an ontology too. It decomposes target (...) space in a way that exhibits certain invariances, which in turn are functionally significant. A challenge for empirical research is to determine which are the functional regularities guiding this decomposition process. What are the explicit and implicit assumptions about the structure of reality, which at the same time shape the causal profile of the brain's motor output and the representational deep structure of the conscious mind arising from it (its "phenomenal output")? How do they constrain high-level phenomena like conscious experience, the emergence of a first-person perspective, or social cognition? By reviewing a series of neuroscientific results, we focus on the contribution the motor system makes to this process. As it turns out, the motor system constructs goals, actions, and intending selves as basic constituents of the world it interprets. It does so by assigning a single, unified causal role to them. Empirical evidence now clearly shows how the brain actually codes movements and action goals in terms of multimodal representations of organism-object relations. Under a representationalist analysis, this process can be interpreted as an internal representation of the intentionality relation itself. We try to show how such a more complex form of representational content, once it is in place, can later function as the building block for social cognition and a for more complex, consciously experienced representation of the first-person perspective as well. The motor system may therefore play a decisive role in understanding how the functional ontology of the human brain could be gradually extended into the subjective and social domains. (shrink)