Chapter 1. Imitation: Thoughts about Theories
in Imitation and Social Learning in Robots, Humans and Animals,
Nehaniv and Dautenhaln.
Course: Robots Learning from Humans
Geonmo Gu
Soojin Jung
Computer Theory and Application Laboratory
School of Computer Science and Engineering
Cognitive Psychology
Department of Cognitive Science
http://theory.snu.ac.kr
Contents

Introduction

The Correspondence Problem

Three theories



Active Intermodal Mapping (AIM)
Goal-Directed Imitation (GOADI)
Associative Sequence Learning (ASL)





2
Introduction

Imitation as Transferred information between Agents (biological, computational or
robotic autonomous systems).

Challenge in imitation theory:
HOW observation of action facilitates production of matching movements.
3
The Correspondence Problem


The problem for one individual of producing behaviour that matches with behavior it
observes in another.
The observer must formulate motor commands to match visual input
Visual Input
Observer
Model
4
The Correspondence Problem


The problem for one individual of producing behaviour that matches with behavior it
observes in another.
The observer must formulate motor commands to match visual input
Visual Input
Observer
Model
5
The Correspondence Problem


The problem for one individual of producing behaviour that matches with behavior it
observes in another.
The observer must formulate motor commands to match visual input
Motor command
Observer
Model
6
The Correspondence Problem

Observer has


Visual Information of model’s action
Motor information (feeling) of observer’s action
Visual Input
Observer
Model
Observer
Model
Visual information
7
The Correspondence Problem

Observer has


Visual Information of model’s action
Motor information (feeling) of observer’s action
Visual Input
Observer
Model
Visual information
Observer
Model
NO Visual information
8
The Correspondence Problem

Observer has


Visual Information of model’s action
Motor information (feeling) of observer’s action
Visual Input
Observer
Model
Visual information
Observer
Model
Motor information (feeling)
9
The Correspondence Problem

Observer has


Visual Information of model’s action
Motor information (feeling) of observer’s action
feeling
Model
Visual information
Observer
Motor information (feeling)
10
3 Theories on Imitation



1. Active Intermodal Mapping (AIM)
2. Goal-Directed Imitation (GOADI)
3. Associative Sequence Learning (ASL)
<AIM>
<GOADI>
<ASL>
11
3 Theories on Imitation



1. Active Intermodal Mapping (AIM)
2. Goal-Directed Imitation (GOADI)
3. Associative Sequence Learning (ASL)
<AIM>
<GOADI>
<ASL>
12
1. Active Intermodal Mapping (AIM)



Visual representation
Motor representation
Supramodal representation
Organ relation
Observer
Model
Visual representation
feeling
Supramodal representation
Motor representation
13
1. Active Intermodal Mapping (AIM)



Visual information: adult’s tongue-protrusion
Motor information: infant’s feeling
Organ relation: tongue-beyond-lips

Organ: part of body. head, brows, tongue, lips
Tongue-beyond-lips
Facial imitation
14
1. Active Intermodal Mapping (AIM)

Correspondence problem
15
3 Theories on Imitation



1. Active Intermodal Mapping (AIM)
2. Goal-Directed Imitation (GOADI)
3. Associative Sequence Learning (ASL)
<AIM>
<GOADI>
<ASL>
16
2. Goal-Directed Imitation


The GOADI theory of imitation suggests that perceived actions are decomposed into a
series of ‘aspects’.
Only some goal aspects are imitated; movement end-points and the manipulation of
objects are more likely to be imitated than either the effector or the movement path.
17
2. Goal-Directed Imitation


Correspondence problem:
No special relationship between matching movements under GOADI.
Goal imitation: if the movement most commonly associated with the perceived goal is
different from the movement of the model, then goal, but not movement, imitation will
occur.
Perceived
Action
Extracted
Goals
Goal
Representation
Commonly
Associated
Motor program
18
Structures of Models
AIM
Perceived
Action
Supramodal
Representation
Motor
Commands
GOADI
Perceived
Action
Goal
Representation
Commonly
Associated
Motor program
ASL
Perceived
Action
Performance
of
Action
19
3. Associative Sequence Learning


Vertical associations
Indirect vertical associations
20
3. Associative Sequence Learning

Vertical Associations


A few may be innate
The majority are formed in a Hebbian fashion.
21
3. Associative Sequence Learning

Indirect vertical association
 Word
smile
22
3. Associative Sequence Learning

Indirect vertical association
 Word
smile
23
3. Associative Sequence Learning

Correspondence problem (imitation)
Visual Input
Observer
Model
24
3. Associative Sequence Learning

Correspondence problem
Visual Input
Observer
Model
25
3. Associative Sequence Learning

Correspondence problem
Visual Input
Observer
Model
26
3. Associative Sequence Learning

Correspondence problem
Visual Input
Observer
Model
27
3. Associative Sequence Learning

Correspondence problem
Visual Input
smile
Observer
Model
28
3. Associative Sequence Learning

Correspondence problem
Visual Input
smile
Observer
Model
29
Summary
• Correspondence problem
• Active Intermodal Mapping (AIM)
• Goal-Directed Imitation (GOADI)
• Associative Sequence Learning (ASL)
30
Contents

Introduction

The Correspondence Problem

Three theories




Active Intermodal Mapping (AIM)
Goal-Directed Imitation (GOADI)
Associative Sequence Learning (ASL)
Contrasting 3 theories


Issue 1: Effect-dependency
Issue 2: Awareness

Questions for ASL model: about Intention

Conclusion & Discussion
31
Contrasting 3 theories
★ two criteria
Effector-dependency
Awareness
Whether observation can support
effector-dependent learning
Whether Imitation Learning can
occur without awareness
32
Effector-dependency issue
•
Some kinds of Training are not generalized to others.
ex) Right-Left hand using is not convertible (Bapi et al, 2000)
33
Explanation for Effector-dependency
Different predictions of 3 Theories on Effector-dependent observational learning
AIM
Frequency
Principal
Result
GOADI
ASL
None (always effectorindependent)
Rare (Actions not
encoded at global level)
Usual
(transformed into)
Supramodal
representation
action “Effects"
Visual experience paring
with motor activation
various motor outputs
Goal-directed action
ex) finger movement
34
Experiment: Effector-dependent learning by observation.
(Bird and Heyes, 2005; Heyes and Foster, 2002; Osman etal., 2005)
- Observers’ better performing(:typing speed)
the finger movement sequence
with using same finger of model’s
Direct link between Perception & Action
35
Explanation for Awareness
AIM
GOADI
ASL
Awareness
O
O
X/?
Mechanism
Active
Goal-directed
Automatic
Base
not
mentioned
Goal-directed
imitation’ theory
(on next slides)
36
Experimental Evidences for automatic imitation
1. Electrophysiological(MEP) study: Motor facilitation by action observation
(Aziz-Zadeh et al., 2002; Maeda et al., 2002; Strafella and Paus,2000)
2. ‘Chameleon effect’ in social interaction
(Chartrand and Bargh, 1999; Lakin and Chartrand, 2003)
37
Questions for ASL model
•
Intentional vs. incidental imitation
ASL Model is NOT considering
- a representation of the model’s action goals,
- role of amodal (non-sensory, non-motor)
representations of action.
Contrary to our introspective
plausibility
38
Thoughts about the Intentionality issue
Relationship between intentional processing
and the vertical associations mediating imitation
Without Intention,
Movement observation Motor activation by ASL.
Automatic process (e.g.: Hebbian learning.)
normally INHIBITED to prevent overt imitation
With Intention,
Disinhibition on vertical association
Formulation of verbal description of observed action.
c.f) Vocabulary limitation : dancers and gymnasts’ special vocab uses.
39
Conclusion(part 2.)
model’s Goals explaining what is imitated,
Vertical Association explaining How imitation is achieved.
 한 가지 모델만으로 모방 학습에 대해 설명할 필요는 없음.
 모방 학습 상황에 대한 이론으로서, GOADI와 ASL이 상호보충적 설명 가능.
40
Discussion
#1.
Is ‘Imitation’ Default of Human cognitive-behavior system?
How broadly can it be applied over areas? (Social/ Functional / Evolutionary..)
#2.
In the Goal-Directed Imitation
The goal of the imitator is to produce exactly the same body movement.
Cases like this pose the correspondence problem, and yet GOADI is silent about how this problem may be
solved.
41