rp2 - 
 Reaching
and
Grasping
 • ...

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Unformatted text preview: 9/13/10
 Reaching
and
Grasping
 •  Early
experiences
 •  Tool‐use
 Manual
Gestures
as
form
of
Social
 CommunicaBon
 •  Baby
Signing
 •  PoinBng
 Baby
Signing
 1
 9/13/10
 Baby
Signing
 •  Benefits
 •  Detriments
 PoinBng
 9‐months
+
 >
9‐months
 CogniBve
and
Perceptual
Influences
 on
Reaching
and
Grasping
 2
 9/13/10
 Looking
vs.
Reaching
 •  Mismatch
between
looking
tasks
and
reaching
 tasks
 •  Things
that
infants
appear
to
know
as
 measured
via
looking
tasks,
infants
appear
not
 to
know
as
measured
via
reaching
task
 Looking
vs.
Reaching
 •  Object
permanence
 •  A
not
B
error
 •  Understanding
object
properBes
 Object
Permanence
 •  Mentally
represenBng
objects
when
objects
 can
no
longer
be
seen
 •  When
do
infants
possess
an
understanding
of
 object
permanence?
 3
 9/13/10
 Object
Permanence
 
Object
Permanence
 •  When
do
infants
possess
an
understanding
of
 object
permanence?
 •  Depends
on
the
measure
 •  Why
the
discrepancy
between
looking
and
 reaching?
 4
 9/13/10
 A
not
B
Error
 A
 B
 A
not
B
Error
 A
not
B
Error
 •  Reaching
task:
12‐months+
pass
 •  Looking
task:
7‐months
pass
 5
 9/13/10
 A
not
B
Error:
ExplanaBons
 •  Infants
do
not
understand
that
an
object
exists
 independently
of
their
acBons
on
it,
and
 hence
they
expect
to
find
an
object
where
 they
previously
found
it.
(Piaget)
 A
not
B
Error:
ExplanaBons
 •  Memory
limitaBons
&
poor
inhibitory
control
 A
not
B
Error:
ExplanaBons
 •  Response
system
(favors
repeBBon
of
a
 previously
successful
motor
response)

 Representa-onal
system
(favors
responding
 based
on
mental
representaBon)
 6
 9/13/10
 A
not
B
Error:
ExplanaBons
 •  Strong
tendency
to
repeat
previous
motor
 behavior
 A
not
B
error
 •  Why
looking
not
reaching?
 •  Knowing
as
different
from
acBng
on
that
 knowledge
 Understanding
Object
ProperBes
 •  What
do
infants
understand
about
the
solidity
 of
objects?
 7
 9/13/10
 Understanding
Object
Solidity:
 Drawbridge
Study
 Understanding
Object
Solidity:
 Wall
Study
 Understanding
Object
Solidity
 •  Looking
tasks:
by
3
to
4‐months
of
age
look
 longer
at
the
impossible
event
 •  Reaching
tasks??
 8
 9/13/10
 Understanding
Object
Solidity:
 Door
Studies
 Understanding
Object
Solidity:
 Door
Studies
 •  Looking
study
version
with
toddlers

 Understanding
Object
Solidity:
 Door
Studies
 •  Why?
 •  CoordinaBng
the
appropriate
amount
of
 knowledge
with
appropriate
acBon
 9
 9/13/10
 Looking
vs.
Reaching
 •  Having
knowledge
versus
using
knowledge
 •  Motor
effects
from
prior
reaches
 CogniBon‐AcBon
Tradeoff
 •  Limited
amount
of
aeenBonal
resources
 •  Divided
aeenBon

interference
 –  Loss
of
speed/
quality
of
performance
in
one
of
 the
acBviBes
 –  Both
acBviBes
affected
 –  Second
acBvity
ignored
 CogniBon‐AcBon
Tradeoff
 •  How
much
of
an
infant’s
reach
is
cogniBvely
 driven
vs.
motorically
constrained?
 •  Boudreau
and
Bushnell
(2000)
 –  Manipulated
cogniBve
components
of
a
task
and
 the
motoric
components
of
a
task
 –  Have
to
pay
aeenBon
to
2
task
components
 simultaneously
 10
 9/13/10
 Motoric
ManipulaBon
 CogniBve
ManipulaBon
 CogniBon‐AcBon
Tradeoff
 •  Increased
motor
demands,
decreased
 cogniBve
performance
 •  Increased
cogniBve
demands
for
planning
and
 execuBng
a
reach
lead
to
slower
motoric
 responding
 11
 9/13/10
 Understanding
object
properBes
 •  Reaching
and
grasping
 Grasping
Pictures
 Grasping
Pictures
 12
 9/13/10
 Grasping
TV
images
 Grasping
Pictures
 •  Do
9‐months
think
the
picture
is
a
real
object?
 Grasping
Pictures
 13
 ...
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