This target article draws together two groups of experimental studies on the control of human movement through peripheral feedback and centrally generated signals of motor commands. First, during natural movement, feedback from muscle, joint, and cutaneous afferents changes; in human subjects these changes have reflex and kinesthetic consequences. Recent psychophysical and microneurographic evidence suggests that joint and even cutaneous afferents may have a proprioceptive role. Second, the role of centrally generated motor commands in the control of normal movements and movements (...) following acute and chronic deafferentation is reviewed. There is increasing evidence that subjects can perceive their motor commands under various conditions, but that this is inadequate for normal movement; deficits in motor performance arise when the reliance on proprioceptive feedback is abolished either experimentally or because of pathology. During natural movement, the CNS appears to have access to functionally useful input from a range of peripheral receptors as well as from internally generated command signals. The unanswered questions that remain suggest a number of avenues for further research. (shrink)

Reviews evidence which suggests that there may be little or no direct introspective access to higher order cognitive processes. Ss are sometimes unaware of the existence of a stimulus that importantly influenced a response, unaware of the existence of the response, and unaware that the stimulus has affected the response. It is proposed that when people attempt to report on their cognitive processes, that is, on the processes mediating the effects of a stimulus on a response, they do not do (...) so on the basis of any true introspection. Instead, their reports are based on a priori, implicit causal theories, or judgments about the extent to which a particular stimulus is a plausible cause of a given response. This suggests that though people may not be able to observe directly their cognitive processes, they will sometimes be able to report accurately about them. Accurate reports will occur when influential stimuli are salient and are plausible causes of the responses they produce, and will not occur when stimuli are not salient or are not plausible causes. (shrink)

People experiencing alien control report that their thoughts, movements, actions, and emotions have been replaced by those of an "other." The latter is commonly a perceived persecutor of the patient. Here I describe the clinical phenomenology of alien control, mechanistic models that have been used to explain it, problems inherent in these models, the brain deficits and functional abnormalities associated with this symptom, and the means by which disordered agency may be examined in this perplexing condition. Our current state of (...) knowledge implicates potentially reversible dysfunction in certain key brain regions (especially the right parietal cortex), which is temporally related to the presence of symptoms. Alien control is quintessentially a disorder of agency. (shrink)

We often consciously will our own actions. This experience is so profound that it tempts us to believe that our actions are caused by consciousness. It could also be a trick, however – the mind’s way of estimating its own apparent authorship by drawing causal inferences about relationships between thoughts and actions. Cognitive, social, and neuropsychological studies of apparent mental causation suggest that experiences of conscious will frequently depart from actual causal processes and so might not reflect direct perceptions of (...) conscious thought causing action. (shrink)

This paper offers a framework for consciousness of internal reality. Recent PET experiments are reviewed, showing partial overlap of cortical activation during self-produced actions and actions observed from other people. This overlap suggests that representations for actions may be shared by several individuals, a situation which creates a potential problem for correctly attributing an action to its agent. The neural conditions for correct agency judgments are thus assigned a key role in self/other distinction and self-consciousness. A series of behavioral experiments (...) that demonstrate, in normal subjects, the poor monitoring of action-related signals and the difficulty in recognizing self-produced actions are described. In patients presenting delusions, this difficulty dramatically increases and actions become systematically misattributed. These results point to schizophrenia and related disorders as a paradigmatic alteration of a ''Who?'' system for self-consciousness. (shrink)

Are we the robots? This question surfaces often in current psychological re- search, as various kinds of robot parts-automatic actions, mental mechanisms, even neural circuits-keep appearing in our explanations of human behavior. Automatic processes seem responsible for a wide range of the things we do, a fact that may leave us feeling, if not fully robotic, at least a bit nonhuman. The complement of the automatic process in contemporary psychology, of course, is the controlled process (Atkinson & Shiffrin, 1968; Bargh, (...) 1984; Posner & Snyder, 1975; Shiffrin & Schnieder, 1977), and it is in theories of controlled processes that vestiges of our humanity reappear. Controlled processes are viewed as conscious, effortful, and intentional. and as drawing on more sources of information than automatic processes. With this power of conscious will, controlled processes seem to bring the civilized quality back to psychological explanation that automatic processes leave out. Yet by reintroducing this touch of humanity, the notion of a controlled process also brings us within glimpsing range of a fatal theoretical error-the idea that there is a controller. (shrink)

Participants watched themselves in a mirror while another person behind them, hidden from view, extended hands forward on each side where participants’ hands would normally appear. The hands performed a series of movements. When participants could hear instructions previewing each movement, they reported an enhanced feeling of controlling the hands. Hearing instructions for the movements also enhanced skin conductance responses when a rubber band was snapped on the other’s wrist after the movements. Such vicarious agency was not felt when the (...) instructions followed the movements, and participants’ own covert movement mimicry was not essential to the influence of previews on reported control. (shrink)

The abilities to attribute an action to its proper agent and to understand its meaning when it is produced by someone else are basic aspects of human social communication. Several psychiatric syndromes, such as schizophrenia, seem to lead to a dysfunction of the awareness of one’s own action as well as of recognition of actions performed by other. Such syndromes offer a framework for studying the determinants of agency, the ability to correctly attribute actions to their veridical source. Thirty normal (...) subjects and 30 schizophrenic patients with and without hallucinations and/or delusional experiences were required to execute simple finger and wrist movements, without direct visual control of their hand. The image of either their own hand or an alien hand executing the same or a different movement was presented on a TV-screen in real time. The task for the subjects was to discriminate whether the hand presented on the screen was their own or not. Hallucinating and deluded schizophrenic patients were more impaired in discriminating their own hand from the alien one than the non-hallucinating ones, and tended to misattribute the alien hand to themselves. Results are discussed according to a model of action control. A tentative description of the mechanisms leading to action consciousness is proposed. (shrink)