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Manos Tsakiris†, Patrick Haggard†, Nicolas Franck‡, Nelly Mainy‡ & Angela Sirigu‡
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Institute of Cognitive Neuroscience Department of Psychology
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Afferent and Efferent Contributions To Self-Recognition
COGNITIVES
This study was sponsored by the Experimental Psychology Society, UK
† Institute of Cognitive Neuroscience, UCL, London, ‡ Institut des Sciences Cognitives, CNRS, Lyon
Abstract We manipulated efferent information in order to investigate the relative contributions of efferent and afferent (proprioceptive) information to self-recognition. Self-recognition was significantly more accurate when participants were the authors of the action, even though there was a perfect matching between the proprioception and the visual feedback across conditions. Efferent information therefore plays a key role in self-recognition, even when subjects judge the effect of an action on a spatially remote body part.
I How Do We Recognize Ourselves ?
The “Williams” Debate
Body (peripheral or afferent)
(see Petit, 2002)
The respective roles of afferent and efferent information in self-recognition are yet to be determined…
View Own Hand
ly al rn d te rate x e E en n G ctio A
Methods & Materials Both hands were covered with identical gloves Participants and experimenter always performed the same movement. 4 blocks, each block with 30 trials, 15 trials for each visual feedback condition (own/other), randomized Image duration = 2000ms (go-signal at 500ms) N=18 right-handed (+0.87), mean age 24.1
Cam 2
Cam 1
Afferent information originating from their right hand was identical, but the efferent information was manipulated by design.
Image
Subject
Subject
Experimenter
Cam 1
Image
Go-Signal : Action
Own hand
Subject
Experimenter
! Efference = Temporal Predictability 9Go-Signal across conditions 9Bad trials excluded
! Spatial Distribution of Attention 9If anything, it would suggest improved performance in passive condition
or Other’s hand
Experimenter
Subject
0
Differential contribution of information in self-recognition.
Mean Proportion of Correct Responses ** 0.969
** 0.6237
0.6
0.4554
0.2 0 self-generated action externally-generated self-generated action externally-generated action action view 'own hand'
afferent
and
efferent
Self-recognition was significantly better when efferent information was present, for both the “view own hand” and “view other’s hand” conditions.
0.91
1
IV Discussion Artefactual Explanations?
Other’s hand
500ms
0.4
Z=-2.635, p<0.01
or
Image Onset : Rest
Self-generated vs. Externally-generated
Self-generated vs. Externally-generated
Own hand
Image
0.8
View Other's Hand Condition
“Whose hand did you see?”
Experimenter
2000ms
III Analysis & Results
Z=-2.062, p<0.05
What the subject sees, looks like her right hand, and what she feels, looks like what the hand on the screen feels.
tim e
d lf ate Se ener n G ctio A
Image
Externally-generated Action
Authorship of Action
Own Hand Other’s Hand
View Other’s Hand
Cam 2
Visual Feedback
Cam 1
Self-generated Action
(2x2 Factorial)
View OWN Hand Condition
In the present study, efferent information was manipulated by design!
Across conditions and trials :
II Experimental Design
Non-parametric Wilcoxon matched-pairs-tests
In previous studies, afference and efference were present across all conditions, and therefore, it was not possible to establish their respective roles. The question whether the performances observed were due to a better integration of visuo-proprioceptive information or due to use of fine efferent information could not be conclusively answered.
Cam 1
Intention Efference copy Predictions of the motor system
W Wundt : Central efferent copy of the motor command
Daprati et al. (1997) & Sirigu et al. (1999) were the first to study self-recognition in schizophrenic and parietal patients respectively.Van den Bos & Jeannerod (2003) investigated the role of “sense of action” and “sense of body” in self-recognition. In the present study we used a task similar to the one developed by Daprati et al., in an attempt to investigate the relative contributions of efferent and afferent information to self-recognition.
Cam 2
Action (central or efferent)
W James : Knowledge of our movements originates from peripheral information
Cam 2
Proprioception : sense of the self par excellence Multisensory integration
Past & Present
view 'other's hand'
By comparing only visual and proprioceptive signals, participants were unable to accurately discriminate between self and other, and they performed at chance! Participants over-recognized themselves in the case of an externally-generated action, by misattributing the other’s hand to themselves. Efference improved the comparison between proprioceptive and visual representations of a remote bodily effect.
V Conclusion Then why?
Self-recognition was significantly more accurate when
Action representations encode not only kinematic and motor parameters, but also the final configurations, the effects of the action.
efferent information was present, even though there was
Efferent processes, implemented in distributed and multisensory forward models, are likely also to be important for self-recognition and self-awareness, and not only for motor control.
a perfect matching between the proprioception and the visual feedback across conditions, and despite the fact that it was the effect, and not the action per se, that the
Parmigianino, Self-Portrait in a Convex Mirror, c. 1524
subjects were watching.
Efferent information played the major role in selfrecognition. In the presence of only afferent information, participants performed at chance! ICS, Lyon, September, 2002
Future… References Daprati E , Franck N, Georgieff N, Proust J, Pacherie E, Dalery J & Jeannerod M (1997). Looking for the agent : an investigation into consciousness of action and selfconsciousness in schizophrenic patients. Cognition, 65, 71-87. Sirigu A , Daprati E, Pradat-Diehl P, Frank N, Jeannerod M (1999). Perception of self-generated movement following left parietal lesion. Brain, 122, 1867-74. van den Bos E & Jeannerod M (2002). Sense of body and sense of action both contribute to self-recognition. Cognition, 85, 177-187.
Whereas it seems unlikely that efference improves the visual representation, it is still unclear whether efferent information simply improves proprioceptive representation, or whether modulates the comparison process itself. Experiments involving testing of parietal patients and the use of TMS in normal participants are needed. To be continued…
