We got started on a new collaboration to study non-linear motor learning with redundant degrees of freedom in humans and robots. The project is a collaboration with Jochen Steil and Kenichi Narioka from the Cognitive Robotics (CoR lab) at the University of Bielefeld.
Motivated by observations from early infant development, the researchers of the CoR lab have conceived Goal Babbling as a particular efficient means to directly learn inverse models. This technique has for instance been used to learn the inverse kinematics of Festo’s otherwise untractable bionic elephant trunk robot:
We will now study whether also humans perform goal babbling of this kind to learn new sensorimotor skills…
Comments Off on CITEC go2goal project kick-off
Many people will know about the classical experiments on adaptation to prismatic displacement or inversion: If humans wear goggles that spatially distort their field of view, this initially severely disrupts their behaviour. With extended training however, they adapt, and not only by neutralizing the disruption in motor behaviour, but also by restoring the perception of space to how it was before the goggles were put on – to the point that wearing the distorting goggles feels more natural than not wearing them.
For some decades now, researchers have been trying to find out if the same is also possible in time – if we adapt our behaviour to compensate for a feedback delay (imagine a slowly reacting computer game), will this also change our time perception? Does that mean that after adaptation, it feels more natural to have the delay than to act in real time? There remains considerable controversy about this issue within the scientific community – some researchers believe it is possible, some that we can only compensate on the behavioural level, but not in time perception, and yet others seem to think we cannot adapt to delays at all. The results we present in our newest paper: Predictability is necessary for closed-loop feedback delay adaptation help to clear up some of this controversy by showing the importance of environmental predictability for delay adaptation in behaviour AND perception.
So my tentative answer to the question: Do we adapt to delays like we adapt to prismatic distortions? Is: yes – no – maybe – in a way – sometimes. Watch this space. One thing I do know, however, is that the phenomenology of the aftereffect (i.e., having the delay removed after adaptation) is pretty weird:
Example post-test behaviour from the study. The participant tries to follow the black dot with the red dot by moving her hand left and right.
If you move your hand with the expectation to track a target, and the cursor you control moves even before the target (because you incorporated the additional delay into your time perception), it really messes with your sense of agency – it is as if the cursor runs away from you, rather than to be controlled by you, because it moves before you feel you move. Another issue that surely deserves further scientific attention…
Comments Off on Predictability and delay adaptation