Download Understanding Perceptual Motor Function Building Better Robots

Understanding
Perceptual
Motor Function
Building Better
Robots
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• Example:
Dana Ballard and Mary Hayhoe (U. of Rochester)
are interested in active vision:
– Subjects are unaware of gross changes in the visual
scene made during saccades.
– Shows that visual system works to recover only that
information that is necessary for the task at hand.
• Complete pathway from sensors in skin or eyes to
somatosensory cortex to motor cortex to muscle.
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Acuity of infants.
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Visual acuity of infants
• The spatial acuity (ability to see fine detail)
of babies is considerably worse than that of
adults (it's around 20/400 to 20/600 at age 1
month).
• However, the optics of babies' eyes are
fine…it's the retina and cortex that aren't
fully developed.
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Acuity of infants.
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Spatial acuity of infants.
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Spatial acuity of infants.
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Spatial acuity of infants.
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Retina
• Although babies have a normal density of rods,
the lattice of cones covering the retina is very
different than at adulthood.
• Specifically, the cones of babies are
– (1) wider (even in the fovea), yielding course
resolution;
– and (2) shorter, so that they hold less photopigment.
The cone receptors in adults cover approximately 68%
of the adult fovea, but only 2% of newborns.
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Cortex
• The visual cortex of babies is also partially
developed.
• These 3 drawings of neurons at different
stages of development show that the
dendritic trees and interconnections of
neurons become increasingly complex over
the first 6 months of life.
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Cellular Basis of Brain
Development
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Migration of cells
Formation and growth of axons
Formation of dendrites
Formation of synaptic connections
Myelination
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Important Features (2) in
Program of Development
1) Subcomponents of nervous system are formed
from cells whose destination and function are
largely predetermined before they migrate from
the wall of ventricles
2) Development is marked by an initial abundance of
cells, branches, and connections, with important
part of subsequent maturation consisting of cell
death or pruning back of initial surfeit
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Postnatal Brain Development
•Growth spurts:
–3-10 months to 1.5 years (30% weight increase)
–2 to 4 years (5% to 10% weight increase)
–6 to 8 years
–10 to 12 years
–14 to 16 years
(**note consistency of ages with major Piagetian stage changes)
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Earliest Capacities
• Hearing:
– Newborns startle to loud noise
– Turn heads to source of noise, indicating
localization
– Not as acute for some parts of the sound
spectrum as when older
– Sensitivity to sound improves dramatically in
infancy and then more slowly until the age of
10 (at which point it reaches adult levels)
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Biological-Maturation Perspective
• Baby becomes able to interact with
environment in increasingly complicated
ways because of brain maturation
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Environmental-Learning Perspective
• Innate reflexes become coordinated via
learning, a relatively permanent change in
behavior brought about by experience with
the environment
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Environmental-Learning Perspective
• Innate reflexes become coordinated via
learning, a relatively permanent change in
behavior brought about by experience with
the environment
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habituation
classical conditioning
operant conditioning
imitation
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