|
Abstract:
Abstract: If naive subjects compare the perceived weight of a
large object with that of a small object of identical physical
weight the small object feels substantially lighter--even if they
are asked to estimate absolute weight rather than density. It is as
though you expect the large one to be heavier and "set" your
muscles accordingly and it therefore feels actually lighter than
the small object. (The effect disappears with eyes closed.) We
found that three out of four cerebellar patients showed a
substantial reduction in the illusion. In one unilateral patient
the illusion was absent on the affected side alone! The subjects
had no difficulty in the "control" condition of just making weight
discriminations with their eyes closed. If confirmed on additional
patients this finding provides the first clear evidence that the
cerebellum may be involved in purely perceptual and cognitive
"predictions" functioning as a "Grush emulator" for internal
simulations before performing certain tasks. Indeed we suggest that
this may be the main function of this enigmatic organ.
|
