Transcript Auditive Elementarperzepte

Prism Adaptation:
Dependency on Motion Trajectory
Christian Kaernbach
Lutz Munka
Institut für Allgemeine Psychologie
Universität Leipzig
Douglas Cunningham
Max-Planck Institut
für Biologische Kybernetik
Tübingen
Perception and Action
Perception as “Image”
Object
Perception
Sign Theory
Hermann von Helmholtz, 1879
Perception
Action
‫ؤتوك‬
‫زظغن‬
‫هىدج‬
Correlation theories
Perception
serves Action
James J. Gibson, 1979
Experiments with prism goggles
Fresnel prisms
Perception
Action
www.prism-adaptation.de
prism goggle set: 15 €
Experiments with prism goggles
Perception
Problem:
Perception
Action
‫ؤتوك‬
‫ ز ظ غ ن‬ Adaptation 
‫هىدج‬
Action
Perception
Action
central
representation of
spatial knowledge
spatial
knowledge
is distributed
Suspicion: The exact motion sequence is relevant.
Martin, T.A., et al. (1996). no transfer between underhand and overhand throwing
Kitazawa et al. (1997): no transfer between fast and slow reaching
Hypothesis: The Negative Aftereffect (NAE) is greater for the
adapted as compared to an alternate trajectory.
Effect of motion trajectory
– Touch screen
– Horizontal bar as chin rest
– 72 participants,
graded randomly in 4 groups
– target position central (block 2&4)
or horizontally randomized (Block 1&3)
– prism goggles (Block 3) with 16.7° horizontal
shift (left-hand base)
• Block 1 „Familiarization“ with full visual feedback,
20 trials (5 repetitions  4 trajectories)
• Block 2 „Pretest“ without feedback, 20 trials (54)
• Block 3 „Adaptation“ with prism goggles, with full visual feedback,
80 trials (801) a single trajectory is adapted, one per group
• Block 4 „Posttest“ without feedback, 20 trials (54)
Results
passive hand:
Block 4 vs. Block 2
Block 4 minus Block 2
horizontal error [mm]
30
20
10
0
µ = 3 ± 1.8 mm
µ = 1 ± 1.7 mm
PHST
PHAT
temporal dynamics
1
-10
-80 -60 -40 -20 0
20 40 60
-20
-30
30
20
10
0
µ = -46 ± 2.2 mm
µ = -26 ± 2.3 mm
AHST
AHAT
2
3
0
-40
AHAT
AHST
Linear
(AHST)
Linear
(AHAT)
-50
-80 -60 -40 -20 0
20 40 60
-60
horizontal error [mm]
PH passive hand
AH active hand
ST same trajectory
AT alternate trajectory
4
5
Results
familiar / unfamiliar motions
above/below
handiness
temporal dynamics
1
2
3
0
-10
-20
4
5
1
0
AHAT
AHST
-10
2
3
4
5
AHAT: B3 o, B4-2 u
AHAT: B3 u, B4-2 o
AHST: B3 o, B4-2 o
AHST: B3 u, B4-2 u
1
0
-10
-20
-20
-30
-30
-40
-40
-50
-50
-50
-60
-60
-60
-30
-40
Linear
(AHST)
Linear
(AHAT)
PH passive hand
AH active hand
2
3
4
5
AHAT: B234 dominant
non-pref
AHAT: B234 schwach
AHST: B234 dominant
non-pref
AHST: B234 schwach
ST same trajectory
AT alternate trajectory
Discussion of first experiment
•
no transfer of adaptation to unadapted hand
only ca. 50% transfer to alternate trajectory of adapted hand
•
passive decay of adaptation
unfamiliar motions are affected more
 adaptation seems not to depend on recalibration of proprioception
otherwise 100% transfer to be expected.
 relearning of motor scripts ?
 Objection: same starting position, but slightly different end position,
end position of unadapted trajectory was not adapted.
Some more experiments
Varying the starting position
-90
-80
-60
Negative Aftereffect[mm]
Negative Aftereffect [mm]
-90
-51
-30
0
same
Interposing circular movements
different
starting
position
-60
-59
-49
-30
0
same
different
trajectory
Some more experiments
With/without weighted wrist wrap
Vertical generalization
-90
-60
-55
-44
-30
0
same
different condition
Negative Aftereffect [mm]
Negative Aftereffect [mm]
-90
tested
-60
high
medium
low
-30
0
adapted high
both
low
Some more experiments
Temporal dynamics of adaptation in block 3
Alternate full/no feedback
/
Terminal feedback
blind (alt. with full feedback)
terminal feedback
Horizontal error [mm]
100
90
80
70
60
50
40
30
20
10
0
0
5
10
15
# of feedbacks
20
Conclusions
• Adaptation does not transfer to the passive hand,
nor fully to alternate trajectories of the adapted hand.
• Adaptation of pointing performance involves mainly
relearning of motor scripts.
• Spatial motor knowledge is distributed.
There is no central representation of spatial motor knowledge.
Knowing where is knowing how to.
• But what about our phenomenal experience?
It seems that it is not needed for direct motor actions like pointing, grasping etc.
– blindsight patients catching balls
– Stratton (1897) riding bicycle with inverting goggles
with phenomenal experience still upside-down.
• What is phenomenal experience good for?
It seems to be a late product of evolution, enabling us to plan alternative action schemes.
Tolman, E.C. (1948). Cognitive maps in rats and men. Psychological Review, 55, 189-208.
Conclusions
Two spatial representations:
I
II
unconscious
conscious
distributed
uniform, central
precise
distorted
motor actions
action planing
Illusion:
Spatial knowledge is
conscious
uniform, central
precise
motor actions, planing
Under ecological conditions perception and action work hand in hand
without significant discrepancies, thus leading us safely through our
daily activities. However, dissociations between space perception and
spatial action are also well-known: Several figural illusions (e.g. the
Müller-Lyer or the Titchener/Ebbinghaus illusions) deceive perceptual
judgment but exert only a marginal influence on motor behavior like
pointing and grasping. The aim of the symposium is to find the causes
of these dissociations and to relate them to the contributions of motor
processes to perceived visual space.
• Does the proposed dissociation between two spatial representations
answer the “illusion question” in the abstract of this symposium?
Yes.