Curs us Doelgericht Handelen (BPSN33). R.H. Cuijpers, J.B.J. Smeets a nd E. Brenner (2004). On the relation between object shape and grasping kinematics. J Neurophysiol , 91: 2598-2606.
R.H. Cuijpers, J.B.J. Smeets and E. Brenner(2004). On the relation between object shape and grasping kinematics. J Neurophysiol, 91: 2598-2606.
R.H. Cuijpers, E. Brenner and J.B.J. Smeets (2006). Grasping reveals visual misjudgements of shape. Exp Brain Res 175:32-44
Many levels of description:
Degrees of Freedom
How does the brain ‘plan’/compute the desired motor neuron output?
Method of research in visuomotor control:
Haptic = by touch Proprioceptor = sensory receptor in muscles, tendons or joints
Fingertip positions and object size
Fingertip positions and object orientation
Goodale (1993); Milner, Goodale (1993)
Agliotti, De Souza, Goodale (1995):
Brenner, Smeets (1996):
Glover & Dixon (2001)
Illusion mainly affects planning
Smeets et al. (2002)
Scaling grip orientation = slope + 1
Suppose:grip orientation = mixture between cylinder orientation + comfortable grip
Slope a =w-1
Offset b = -(w-1)f0
Gradual increase: grip errors were planned that way
High correlation despite errors!
Sudden drop at end: Grip aperture automatically corrected
Correlation much higher for max. grip aperture than final grip aperture
With consistent haptic feedback
If distributions are Gaussian with zero mean, we get:
For the circular cylinder w=0, so that: