Image Schemas

7/31/2019 Image Schemas

http://slidepdf.com/reader/full/image-schemas 1/22

CS 182

Midterm review



Image schemas

• What is a schema?

– a pattern capturing structure in the world

• What is an image schema? – a schema about interaction with the world

• Can you name some?

– Containment

– Source-Path-Goal

– Part-whole

– Near-far



Image schemas

• Think of image schemas as the “basic

categories” of interaction with world

• Image schemas have basis in interaction with

world and with neural structures

– Of course, neural structures should capture

regularities in interaction with world

– Not linked to a specific neural area

– Instead, linked to a neural CIRCUIT



English

ON

AROUND

OVERIN

Bowerman & Pederson



Dutch

Bowerman & Pederson

AAN

OM

BOVENIN

OP



Chinese

Bowerman & Pederson

SHANG

ZHOU

LI



The collection of image schemas

• Trajector / Landmark (asymmetric)

– The bike is near the house

– ? The house is near the bike

• Boundary / Bounded Region

– a bounded region has a closed boundary

• Topological Relations – Separation, Contact, Overlap, Inclusion, Surround

• Orientation

– Vertical (up/down), Horizontal (left/right, front/back)

LMTR

bounded region

boundary



Learning System

We’ll look at the

details next lecture

dynamic relations

(e.g. into)

structured connectionist

network (based on

visual system)



Outline 1/3

• Biology

– Neuron mechanics

• spiking, neurotransmitters, ion channels, Na+

– Development

• growth cones, chemical gradients, activity-dependent

pruning

• Models

– McCullough-Pitts model

• backpropagation: minimize error by slow steps

– triangle node

• recruitment learning



Outline 2/3

• Psych experiments

– Stroop task, priming, spreading activation

• Brain study

– PET, fMRI, EEG, MEG, TMS, lesion, single-unit

• Learning

– backprop, Hebbian, LTP, calcium, retrograde, blank slate(not)

• Colors

– language variations and invariants; intermediate

representations



Outline 3/3

• Categories

– basic categories: functional distinction & effects

– category structure

• Schemas

– Image schemas

– FrameNet

– Regier's model

• hand-built feature extraction, learned mapping



Neurobiology

• Ion pumps

– polarized

– resting potential

– ions: Na+, K+, Cl-

• Neurotransmitters

– voltage admits Ca+, vesicles to release transmitters

– bind to ionotropic receptors

– allow ions into postsynaptic cell

• different types of ions for different receptors/transmitters



Neurobiology 2

• Action potential

– threshold

– all-or-nothing

– voltage-gated channels

– refractory period

• Myelin

– electrical transmission

– only in mammals



Neural development

• Neurons migrate to correct positions

• Grow axons with “growth cones” on tips

• Axons follow chemical gradients in increasing or

decreasing directions, attracting or repelling them

– brain areas grow axons generally together

• Axons meet other neurons, form synapses

– overconnect

– prune based on activity

– humans not blank slate!



The McCullough-Pitts Neuron

y j: output from unit j

Wij: weight on connection from j to i

xi: weighted sum of input to unit i

xi f

y jwij

yi

xi = ∑ j wij y j

yi

= f(xi)

ti : target



Backpropagation

• Minimize squared error

– gradient descent

– use momentum (constant times previous change)• Minimum error on training set may not be

minimum error on all data!

– overfitting

• memorize training data at expense of generalization

– reduce it by checking against a validation set or

just stopping early



Triangle nodes

• Triangle nodes – Reciprocal connections to three other units

– Activates whenever 2 units activate

– Activates all 3 units

– Can be implemented as group of McCullough-Pitts

neurons

• Recruitment learning

– Intermediate units activated by multiple sources

strengthen connections to sources

– Now intermediate unit represents conjunction



Hebbian learning

• Neurons that fire together, wire together

– If presynaptic neuron helps cause postsynaptic neuron to

fire, synapse strengthened

• Biology

– Ca2+ enters postsynaptic cell when synapse active and cell

fires

– Temporarily makes receptors more sensitive; also slowly

adds new receptors

– releases nitrous oxide (NO)--retrograde messenger

• causes changes in presynaptic neuron, too

• releases more neurotransmitter



Psych experiments• Measure behavioral differences that indicate processing

differences

– Stroop task

• difficulty in reading words in other color

• indicates topic-specific interference in languageprocessing

– Word priming

• related words make recognizing words faster

• timing-dependent effects

– opposite words speed up without time to process;

slow down processing with more time

– explained by slower-onset inhibition



Brain study

• PET

• fMRI

• lesion

• EEG

• single-unit recording

• TMS



Colors• Biology

– 3 input signals

– neural representations of sums & differences

• e.g. yellow = green + red – blue

• Psychophysics

– quantitative measurements of psychological quantities

– e.g. find out how small a color difference subjects can discern

• Language

– different languages have different groups

– certain groupings maintained: no one groups red + green

– certain central concepts maintained: no one says turquoise is agood example of “grue” (green-blue color group)

Image Schemas

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