Read Online The Illusion of Conscious Will by Daniel M. Wegner - Free Book Online

is exactly the same thing as the experience of will, and so they examined the sensation earnestly and deeply.
    Much study and thought has been devoted to the sense of effort that seems to be involved in the intriguing case of eye movement. When one moves the eyes normally, the visual world is seen as unchanged despite the fact that the image of that world on the retina is in fact moving about. However, when the eye is moved passively, the visual world seems to move. Tapping on the eyelid with your eye open, for example, makes your eye jump about a bit, and the world you see with that eye jumps about as well. This suggests that in the intentional movement of the eye, there is some sensation of the effort of eye movement that can then be used by the brain to adjust its perception of the visual world for the movement. A kind of internal feedback or cancellation of the intentional action seems to be necessary to create this phenomenon. Isolating the pathways of such feedback has preoccupied a generation of physiologists.
    The issue has been sufficiently baffling, however, to inspire one researcher to have an operation performed on his own big toe to see if tension on a muscle tendon all by itself is perceptible (it is; the researcher was the senior author of McCloskey, Cross et al. 1983). Much of the research in this area is meticulously grisly because it depends on carefully ruling out a variety of sources of sensation (by the anesthetization of skin or joints, for example) before people are asked to judge their degree of effort in various tasks. This is necessary because people can get feedback about their movement not just through muscle discharges but also through nerves in the skin and bones (not to mention by looking). The issue is still not resolved, but the best guess at this time is that both kinds of sensation exist—sensation of the motor command from the brain and sensation of the muscle moving—and that both can contribute to the sense of effort we experience in performing muscle movement (Gandevia, 1987; Jeannerod 1997; Jones 1988; Matthews 1982; McCloskey 1978; Roland 1978).
    The most striking cases relevant to muscle sense involve people with no muscle sense at all. In extremely rare instances, apparently because of unidentified viral infections, people have lost the return sensations from their muscles while at the same time retaining their ability to send commands to those muscles. Jonathan Cole (1995; Cole and Paillard 1995) re-ports on one such man, Ian Waterman, and his profound action problems. Struck by a mysterious illness at the age of nineteen that stopped his muscle sensations below the neck, Waterman first simply slumped into a heap, unable to control even moving an arm or sitting up. He had to watch all his actions to see what effect they were having, and if he didn’t pay rapt attention at all times, the act would fail. If he looked away toward one arm he was trying to move, the other arm might flail about. Even sitting still was a challenge. If he didn’t watch his hands, they could float away. And if he lost concentration as he was sitting, he could easily fall over.
    Although Waterman learned to walk after prodigious effort over many months, he had to look down at his limbs all the time to guide his movements, and he remained uncomfortable walking with people or in unpredictable environments because any unanticipated bump could throw him to the ground. Without the ability to sense his movements, he also couldn’t make adjustments that people make quite automatically to catch themselves before they fall. Walking in close quarters was out of the question, as any jostling could yield a spill. Even the most minor issues had to be thought out in detail—for example, he needed to remember to shift his body backward slightly whenever he extended his arm, so that the weight of his outstretched arm would not make him fall forward. Apparently, the ability to send signals to the muscles without learning