Modeling and Imagery: Intro

Wilson & Knoblich, 2005

Conspecifics? The case for motor involvement in

perceiving conspecifics•The idea that we use a part of motor cortex to

interpret the movements of others of our species Starts with the notion that other people are

special (perceptually), because they can be directly compared with ourselves (& they’re the only thing that can be)

Perceiving people Generates motor representation

•But no movement•So why have a movement plan without movement?

Purpose?• It’s proposed here it’s for an emulator

•This is something that in computer hardware/software terms enables programs intended for one device to run on others

•Perhaps the motor plan enables us to predict other’s actions

Covert imitation of actions Chameleon effect

•Facial expression (cinema, the nodder)•Gestures & body sway (mothers/babies,

launderette, bar)•Tone of voice, pronunciation (Janet & Corinne)

•Ever watched a sport you play and experienced that you are “playing” yourself?

Q1

Covert imitation of actions Automaticity of imitation

•Stimulus-response compatibility•Responses fastest when cue matches response•Suggests motor programs for response are best cued by

watching the same or similar action• Which in turn suggests imitation is automatic

Covert imitation of actions Neonate imitation

•One-month olds•Mouth opening, tongue protrusion, facial expression of

emotion, blinking, vowel sounds, /m/ sound…

•“Slightly older”•Tongue protrusion to side, more consonants

Covert imitation of actions Frontal lobe damage

Loss of inhibition Automatic tendency to imitate

•(evidence for covert but inhibited imitation in the rest of us)

Q2

Covert imitation of actions Mirror Neurons

• Previous examples: overt imitation

• This example: covert imitation exists when overt behavior is absent

• These neurons (in premotor cortex of monkey) fire both when acting and when watching action

Diagram shows activity in both premotor and

parietal areas

Q3

Covert imitation of actions Mirror Neurons

• Previous examples: overt imitation• This example: covert imitation exists when overt behavior

is absent• These neurons (in premotor cortex of monkey) fire both

when acting and when watching action• Note: this is in monkeys, not humans, but the idea is that

perhaps we also have imitative circuitry in our brains

Q3

Covert imitation of actions Activation of motor planning

areas in humans• Observation of other’s body

movement (finger, hand, arm, mouth, foot) leads to activation of motor cortex

• Only occurs for plausible movements

• Also occurs for complex movements…more so for those who are expert in the activities (but for non-experts too – important!)

• Heard sounds promote activation of hand parts of motor cortex

Q4

Covert imitation of actions Activation of motor planning areas in humans

• Observation of other’s body movement (finger, hand, arm, mouth, foot) leads to activation of motor cortex

• Implies new mappings can be learned• As long as distant stimulus is movement (e.g. keystroke), near

stimulus can vary (e.g. sound of music, sight of music, both sigh and sound...)...any will elicit motor activation

• Thus music can be “heard” as movement, provided you are familiar with the required movement

Q4

Covert imitation of actions Facilitated muscle activity

•Trace EMG activity found in response to watching same limbs of others move

Motor related brain rhythms•Rhythms blocked by motor activity are also

blocked by observation•Suggests equivalence of perceived and performed

action

Why do we covertly imitate? Might be due to the need for action

understanding…• To assist in categorizing the action• To uncover the purpose behind the behavior• To understand the antecedents of the action (why do this?

Affective state)• Makes sense if both sensory and motor consequences are

initiated

Might be something to do with language evolution• Area F5 & Broca’s area

Why do we covertly imitate? …or we might be trying to perceive what we are

seeing• Serves as an “emulator”

• Can perhaps be used to fill in missing or scratchy information• Can perhaps be used to project likely movements of other’s

body even when unsighted• Info must permeate other systems beyond the motor system

for this to work• Could be really useful in observational learning

p. 464

Q5

Why do we covertly imitate? Contrasts w/other (previous) proposals

• Others “postdictive”, this is predictive• (postdictive – look back to uncover intentions)

This requires allocentric (not relying upon the perspective in which it is viewed) representation of body• Can map something watched in 3rd person as experienced

in 1st person• Clear tie ins for modeling, no?• My answer to q. 5 may take liberties with the paper, but I

still like it!

p. 464

Q5

Q6

Perception is predictive Your favorite CD/playlist Similar prediction has been shown in movement

perception• “Representational momentum”

• Forward shift accepted, backward rejected (explain) – p. 465 has further examples

• Suggests perceptual extrapolation• Think of watching a car go behind buildings and emerging the

other side...are you expecting it to emerge?

• “Filling in” – the x-y example• Also found for human movement (see point light display

in ch. 14 slides)

Perceptual Prediction & Emulation

How does it work?• Internal model – forward model (Jordan)

•Avoids dependence on feedback (important when considering chronometry) in ballistic movements

•Think of the anticipation that grows when learning the red box blue box game

Perceptual Prediction & Emulation

How does it work?•Emulators (again)

• See definition on p. 466• Model of external system run internally, in real time

• Implies information about external world can be had before it occurs

• Emulation easier for simple patterns, or for very familiar patterns

• Supported by the idea that when outcomes are unpredictable, representational momentum is absent (rock bouncing down hill)

Motor involvement in perceptual prediction

There must be a match between what is seen and what is experienced (what is experienced is what builds the emulator)• In the case of watching human bodies, the match

is pretty good – we have one, so we “know” how it behaves

Does covert imitation get used for perceptual prediction in human movement?

Motor involvement in perceptual prediction

Motor activation that precedes the related perceptual event•Need to show evidence that MA precedes the

event for the predictive model to make sense•Pianists generate motor imagery prior to the

event that relates to it•Motor activation of a finger used to play a note occurs

prior to the note being heard in a familiar piece of music

Q7

Motor involvement in perceptual prediction

Predictive capabilities of mirror neurons•Mirror neurons that fire to a hand grasp of an

object also fire when the hand is seen about to grasp when going behind a screen…but only if it is known there is an object behind the screen

Motor involvement in perceptual prediction

Influence of motor learning on perception•When a particular movement pattern is learned,

subsequent recognition of similar movement patterns improves

Q8

Motor involvement in perceptual prediction

Superior perceptual prediction by viewing oneself• Idea here is that if the internal model is based on

an estimation of the external reality, then it should be best when the external reality is one’s own!•And it is borne out•People watching themselves perform better in point

light task identification then those watching othersQ10

Q9

Motor involvement in perceptual prediction

Superior visual judgment for possible movements•Perceptual prediction is influence by motoric

knowledge

So, um, what? Internal emulators imply perceptual

sophistication of unparalleled complexity That these are unconscious implies there is a

lot going on of which we are not aware That the events invoke motor imagery is

really important…see next week’s audio slides