The Development of Tool Use in Infancy

Talk Overview  Background: Understand infant cognitive development  The Problem of Tool Use: What is required What develops  Mechanisms of Development: Behavioural schemas (Six mechanisms) Representations (Redescription) Linking Two tracks  Reflection, and Direction for Roboticists  Psychology Robotics research

Timeline of Development Birth months Free Play: stereotypical accommodative relational simple relational functional relational Overlapping waves (Siegler)

Timeline of Development Free Play: stereotypical accommodative relational Problem solving: support string stick radial grasp shapes in slots Birth months simple relational functional relational  Two essential aspects always present  Play: vary situations, performance, discover how it works  Problem Solving: discover means good for particular goals

The Problem of Tool Use  Selecting the right tool or tools  Spatially arranging the right relationships (between tools and target objects)  Performing the appropriate manipulations  Degrees of Freedom  Solve by  Forward Search  Forward Search with Heuristics  Means-end

What Develops in Infants?  Planning seems to be present early  Some improvements in Memory, Backtracking, Inhibition  Development of Schemas (≈ Planning Operators)  Sensorimotor Schema  Development of Representations  Objects  Space, spatial relationships  Actions  ….

2 1 What Develops in Infants?  Planning seems to be present early  Some improvements in Memory, Backtracking, Inhibition  Development of Schemas (≈ Planning Operators)  Sensorimoto  Development of Representations  Objects  Space, spatial relationships  Actions  ….

2 1

Mechanisms  M1 Repetition  M2 Variation and selection  M3 Differentiation  M4 Composition  M5 Modularisation  M6 Decomposition

Mechanisms  M1 Repetition  M2 Variation and selection  M3 Differentiation  M4 Decomposition  M5 Composition  M6 Modularisation  Opportunistic Where schema can  Leads to discoveries  (affordance)  (play)

Mechanisms  M1 Repetition  M2 Variation and selection  M3 Differentiation  M4 Decomposition  M5 Composition  M6 Modularisation  Parameter variation  Understand effects  Generate new results  Especially at difficulty  Transition periods

Mechanisms  M1 Repetition  M2 Variation and selection  M3 Differentiation  M4 Decomposition  M5 Composition  M6 Modularisation Branching in behaviour graph  Unexpected result  Find preconditions  Adjust motor action

Branching in behaviour graph Mechanisms  M1 Repetition  M2 Variation and selection  M3 Differentiation  M4 Decomposition  M5 Composition  M6 Modularisation  Borrowed movement too crude  Refine parts  Flexible reassembly

Mechanisms  M1 Repetition  M2 Variation and selection  M3 Differentiation  M4 Decomposition  M5 Composition  M6 Modularisation Behaviour graph (join)  Simple sequence  Hierarchical control

Mechanisms  M1 Repetition  M2 Variation and selection  M3 Differentiation  M4 Decomposition  M5 Composition  M6 Modularisation  Refine by repetition, variation and selection, produce a “smooth atom”  Ready to be used as subunit  (for ongoing development) Behaviour graph (join)

Stereotypical (Without Objects) 1.Arm wave (100%): rapid flapping from shoulder (  surface slapping, waving objects/banging) 2.Finger flex (100%); flexion and extension of all four fingers (  exploratory behaviours with objects) 3.Hand rotate (90%) and flex (80%): a rhythmic rotation, bending and extending of the wrist (  object exploration?) 4.Clap hands together (75%) (  banging objects together) (85%) 5.Finger rotate (15%): similar to turning a large dial (  rotation of lids/dials?)

Single Objects  Reach + Grasp  Developing the Stereotypical Behaviours with Objects:  Waving a rattle  Catch/release or scratch  or squeezing an object, or crushing (e.g. paper) (differentiation (M3), variation and selection (M2))  Multi-sensory Object Exploration  Hand-Surface interaction

Object-Object  Object-surface  object-object  Obstacle removal  Support  String  Lever  Stick ( the magic happens here )  Fitting Shapes into Slots (peg-in-hole task)  Spoon-feeding (and other objects with handles) Reinforcement learning

Timeline of Development Free Play: stereotypical accommodative relational Problem solving: support string stick radial grasp shapes in slots Birth months simple relational functional relational Overlapping waves (Siegler) Really interesting part

stereotypical single objectobject-object DONE

Representations (Objects, Space, …)  Transfer as a proxy Brown: Level of representation rather than age determines transfer efficiency

Representations (Objects, Space) 1.Coarse to Fine Some situations generalise very well, and immediately Sometimes over-generalise (scale errors, incompatible shapes) 2.Context Specific to General 3.Integration of Fragmentary Representations

Representations (Objects, Space) 1.Coarse to Fine 2.Context Specific to General Some situations, do not generalise well at all Spoon for self-feeding, or for directing to another object hand in a slot vs. posting a disk 3.Integration of Fragmentary Representations

Representations (Objects, Space) 1.Coarse to Fine 2.Context Specific to General 1.Integration of Fragmentary Representations “perception leads to multiple representations that may be recruited for different tasks”  4-month-olds perceive 3D form of rotating wireframes  6-month-olds “complete” solid 3D objects  18-month-olds still use fragmentary representations  24-month-olds 3D whole-object geometric representations Advantages of fragmentary / task specific representations: Simple space which for particular task When another seems more appropriate  switch representation

Linking Tracks Sensorimotor & Representation

MOVING OF MOUTH EDGES MOVING OF CONTAINER EDGES

Container (object) Push (action) inside (spatial relationship) Higher order concept broken (object state)

Reflection 1.Planning present early, but few schemas ( planning operators ) 2.Initial Knowledge is Fragmentary and Incomplete “to understand is to invent”, + schedule 3.Infants Learn Slowly, but Thoroughly representations slow to change 4.Generalisation Depends on Representation What are infants good and bad at?  Good: build on what they know, try out, refine, assimilate  Bad: make big leaps  take several months

Emulating in a Robot… 1.Start with Few Schemas, to Get a Lot (Crucial to implement the Mechanisms) 2.Representations Must Develop Gradually 3.Interaction Between the Concrete and Abstract Tracks  Difficult but Crucial (structural bootstrapping)  Addressing the main mystery of development 4.Guiding Examples and Benchmarks for Development

Advancing the Science Many take “inspiration” from infants: Affordances, intrinsic motivation, play Need to: Model whole development, e.g. from 6 to 18 months Aim for Same Behaviour  How do they explore a space?  How is old knowledge re-used?  How robust is the behaviour?  Representation

Psychology Robotics Advancing the Science Modelling: Means-end behaviours X X X X Experiments: Get training into lab