Essay Instructions: This paper is to be in APA format and at least four but no more than five pages long. I require proper citations (at least three) that illustrate your points (fact vs. opinion). This is not a thought paper -- it is an investigation, critique or research proposal related to the paper.
No more than 5 pages.
Make sure that you have at least 3 sources (psychology sources not wikipedia or cnn) and that you've properly cited them in APA style.
PAPER:
Copyright © 2003 American Psychological Society
CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 79
Abstract
Research has demonstrated
that very young infants can discriminate
between visual events
that are physically impossible
versus possible. These findings
suggest that infants have knowledge
of physical laws concerning
solidity and continuity.
However, research with 2-yearolds
has shown that they cannot
solve simple problems involving
search for a hidden object, even
though these problems require
the same knowledge. These
apparently inconsistent findings
raise questions about the
interpretation of both data sets.
This discrepancy may be resolved
by examining differences
in task demands.
Keywords
infant cognition; development;
search tasks
A paradox has emerged in the
developmental literature. On the
one hand, a wealth of research
from more than a decade of exciting
studies shows that very young
infants have knowledge of physical
laws concerning continuity and
solidity (Baillargeon, Graber, De-
Vos, & Black, 1990; Spelke, Breinlinger,
Macomber, & Jacobson,
1992).
On the other hand, recent
work has revealed a surprising
lack of such knowledge in children
between 2 and 3 years of age (Berthier,
DeBlois, Poirier, Novak, &
Clifton, 2000; Hood, Carey, & Prasada,
2000). The question is raised:
Are there true discontinuities, even
regressions, in children’s concepts
of the physical world? Or can the
discrepancies between the infant
and the toddler data sets be resolved
by pointing to differences
in task requirements? Or perhaps
the explanation lies in differences
in methodology. For example, in
the infant studies the dependent
measure is looking, and in the toddler
studies it is active search. Whatever
the explanation, this paradox
must be resolved before a comprehensive
theory of early cognitive
development can be constructed.
Beginning with the seminal article
by Baillargeon, Spelke, and
Wasserman (1985), the emerging
picture of infants has been that 3-
to 4-month-olds show a stunning
sophistication in their perception
of the physical world. The typical
paradigm in this line of research
entails the presentation of an event
(e.g., a rotating screen in Baillargeon
et al., 1985; a rolling ball in
Spelke et al., 1992) during repeated
trials (referred to as
habituation
trials).
Test trials consist of equal
numbers of “possible” (
consistent
)
events, which accord with the natural
laws of physics, and “impossible”
(
inconsistent
) events, which
break those laws. The assumption
is that if infants look longer at incons
i s tent than at cons i s tent
events, they have detected an incongruence
with the physical law.
Representation of Objects and Events:
Why Do Infants Look So Smart and
Toddlers Look So Dumb?
Rachel Keen
1
Department of Psychology, University of Massachusetts, Amherst, Massachusetts
INFANT STUDIES ABOUT
OBJECT AND EVENT
REPRESENTATION
The procedure in the infancy
studies can be clarified by considering
an example from Experiment
3 in Spelke et al. (1992). During habituation
trials, 3-month-old infants
saw a ball roll from the left
and disappear behind a screen. A
bright blue wall protruded above
the screen. When the screen was
lifted, the ball could be seen resting
against the wall on the right side of
the display. Following these trials,
an obstacle was placed on the track
to the left of the wall, with the topmost
part of the obstacle, as well as
the blue wall, showing above the
screen. On test trials, the ball was
again rolled from left to right. For
the inconsistent event, when the
screen was raised the ball was resting
in the old place by the wall, so
that it seemed to have violated
rules of solidity (i.e., two solid objects
cannot occupy the same space
at the same time) and continuity
(objects exist continuously and
move on connected paths over
space and time). By appearing at
the far wall, the ball seemed to
have moved through the solid obstacle
or discontinuously jumped
over it. For the consistent event,
when the screen was raised the ball
was resting against the obstacle, a
novel position but one that conformed
to physical laws. The infants
looked significantly longer at
the inconsistent event than at the
consistent event. A control group
saw the ball in the same positions
when the screen was raised, but the
ball’s movement had not violated
any physical laws. This group
looked at the ball equally in the old
and novel locations, thus indicating
that they had no intrinsic preference
for either display and no
preference for the original position.
80 VOLUME 12, NUMBER 3, JUNE 2003
Published by Blackwell Publishing Inc.
From this and other experiments,
investigators have drawn the conclusion
that very young infants
reason about objects and events by
drawing on some form of knowledge
about solidity and continuity (Baillargeon,
1993; Spelke et al., 1992).
SURPRISING RESULTS
FROM TODDLERS
The discordant results from toddlers
come from experiments presenting
the same type of physical
event—a rolling ball that goes behind
a screen and stops—but in
this case the child’s task is to actually
find the ball (Berthier et al.,
2000). The apparatus (see Fig. 1)
features a wooden screen with four
doors that hides the progress of the
ball down the track. The ball is always
stopped by a barrier, which
can be positioned at any of the four
doors. The cue to the ball’s location
is the top of the barrier protruding
several centimeters above the
screen. If the child understands
physical laws of solidity and continuity,
he or she should open the
door by the barrier. Test trials consist
of the experimenter placing the
barrier on the track and lowering
the screen to conceal the track.
Then the experimenter draws the
child’s attention to the ball and releases
it at the top of the track. Finally,
the child is invited to open a
door to find the ball.
In Figure 2,
the columns labeled
“opaque” show individual performance
on this task in the study by
Berthier et al. (2000). Children under
3 years old performed no better
than would be expected if they
were simply guessing at the ball’s
location. Of 16 children in each age
group, no 2-year-old and only three
2.5-year-olds performed above
chance levels; 13 of the 3-year-olds
did so, however. (Note: Data for
3-year-olds are not displayed in
Fig. 2.) The almost total lack of success
for children under 3 years of
age was quite surprising, and in a
series of studies my colleagues and
I have sought to understand why
their performance is so poor.
Offering more visual information
about the ball’s trajectory
seemed like a reasonable way to
help the toddlers (Butler, Berthier, &
Clifton, 2002). We replaced the
opaque wooden screen with a
transparent one of tinted Plexiglas,
leaving four opaque doors to hide
the bottom of the wall and the
ball’s final resting position. Otherwise
we kept the procedure and
the rest of the apparatus the same.
Now children had a view of the ball
as it passed between doors, with
the additional cue of no emergence
beyond the wall. Despite this substantial
increase in visual information
about the ball’s whereabouts,
2-year-old children still had great
difficulty in searching accurately:
Only 6 out of 20 children performed
above chance. Of the 12
children tested at 2.5 years of age,
10 were above chance, so this age
group benefited notably from the
additional information (see data in
Fig. 2 labeled “clear”).
We also recorded eye gaze, monitored
from a digital video camera
trained on the child’s face. Children
at both ages were highly attentive
as the ball was released,
and they tracked its movement
down the ramp on 84% of trials. Two
aspects of their tracking behavior
predicted their response: the point
where they stopped tracking the
ball and whether they broke their
gaze before choosing a door. For
older children, tracking the ball to
its disappearance was the most
typical pattern, and this virtually
guaranteed they would open the
correct door. A different story
emerged for the 2-year-olds. Like
2.5-year-olds, they typically tracked
the ball to its final location, but this
did not ensure success. If they
looked away after correctly tracking
the ball, they made errors, although
this was not the case for
2.5-year-olds (Butler et al., 2002).
Fig. 1. View of the apparatus used for the toddler task. The child is opening the third
door, and the ball, resting against the wall, is visible through the door. From “Where’s
the Ball? Two- and Three-Year-Olds Reason About Unseen Events,” by N.E. Berthier,
S. DeBlois, C.R. Poirier, J.A. Novak, and R.K. Clifton, 2000, Developmental Psychology,
36, p. 395. Copyright by the American Psychological Association. Reprinted with
permission of the author.
Copyright © 2003 American Psychological Society
CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 81
IS THE PROBLEM KEEPING
TRACK OF HIDDEN
MOVEMENT?
A second visual manipulation
was tried (Mash, Keen, & Berthier,
in press). We hypothesized that if
the children were given a full view
of the ball’s trajectory until it came
to rest against a wall, they would
be able to search correctly. In effect,
we reversed the sequence of events
that concealed the ball: In our previous
studies (Berthier et al., 2000;
Butler et al., 2002), the screen was
first positioned in front of the ramp,
hiding most of it from view, and
then the ball was released at the top
of the ramp, going out of sight
while still moving. In this new
study, the ball rolled down the
ramp and came to a stop by a wall,
then the screen was lowered to
conceal both the ramp and the ball.
At that point, the child’s task was
the same as in previous studies—
open a door to find the ball. Note,
however, that in this case the child
did not have to reason about solidity
and continuity in order to find
the ball. Keeping track of its position
behind the screen was all that
was required.
Allowing complete access to the
ball’s movements benefited the older
children somewhat, but the great
majority of 2-year-olds still had
enormous problems. Only two out
of eighteen 2-year-olds tested performed
above chance, whereas
seven out of eighteen 2.5-year-olds
did. As when we used the clear
screen, gaze offered clues as to
Fig. 2. Proportion of trials correct on the first reach for 2- and 2.5-year olds. Results
are shown separately for trials with an opaque screen and a transparent screen. Each
circle represents one child’s performance. The boxes enclose the second and third
quartiles of the distributions, and the horizontal lines in the boxes are the medians.
From “Two-Year-Olds’ Search Strategies and Visual Tracking in a Hidden Displacement
Task,” by S.C. Butler, N.E. Berthier, and R.K. Clifton, 2002, Developmental Psychology,
38, p. 588. Copyright by the American Psychological Association. Reprinted
with permission of the author.
why children failed. If children
looked at the ball as the screen was
lowered and maintained this orientation
until opening a door, they
were correct about 90% of the time.
Most children, however, broke
their gaze, which resulted in errors.
Merely watching as the screen was
lowered over the ramp and ball did
not aid search; only a continuous
fixation up to the point of choosing
the door led to success.
WHAT ABOUT TASK
DIFFERENCES?
In the infant task, 3- to 4-monthold
infants looked longer at physically
impossible events than at possible
events (Baillargeon et al.,
1990; Spelke et al., 1992). No prediction
was required on the infants’
part, as they simply reacted
to a visual array of an object in the
wrong place or the right place. In
contrast, the search task used with
toddlers involved prediction and
planning within a more complex apparatus.
In order to make the infant
and toddler tasks more comparable,
we designed a looking-time task in
which the same door apparatus
was used, but the children never
opened a door (Mash, Clifton, & Berthier,
2002). Instead, they observed
the same events as before, but a puppet,
Ricky the raccoon, opened the
door.
Most of the time, Ricky opened
the correct door and removed the
ball. But on test trials, Ricky opened
an incorrect door (no ball found, a
physically possible, or consistent,
event) or opened the correct door
but found no ball (a physically impossible,
or inconsistent, event). After
the door was opened and no
ball was found, the experimenter
raised the screen to reveal the ball
resting against the wall (consistent
event) or beyond the wall (inconsistent
event). This visual array is
highly similar to what infants saw
82 VOLUME 12, NUMBER 3, JUNE 2003
Published by Blackwell Publishing Inc.
on the test trials of Experiment 3 in
Spelke et al. (1992), described earlier.
Like the infants, the toddlers
looked longer at the inconsistent
placement of the ball than at the consistent
placement. This result was
independently corroborated by a
looking-time study with toddlers
that used a similar apparatus but a
different procedure in which the
experimenter opened the doors
while the child watched (Hood,
Cole-Davies, & Dias, 2003).
CONCLUSIONS
To interpret the results of these
studies, first consider what can be
ruled out as an explanation of toddlers’
poor performance in this
search task. The results from the
original study using an opaque
screen (Berthier et al., 2000; and
from Hood et al., 2000, as well)
suggested that toddlers have no
knowledge of continuity or solidity.
In the clear-screen study (Butler
et al., 2002), 2-year-olds again
failed to recognize the barrier’s role
in stopping the ball. Maintaining
gaze on the spot where the ball disappeared
was the behavior most
predictive of correct door choice—
more evidence that toddlers did
not reason about this physical
event. But unexpectedly, taking
away the reasoning requirement did
not lead to success. Observing the
disappearance of a stationary ball
should have enabled the children
to select the correct door if the
problem were either hidden movement
or the necessity to reason
about the barrier’s role (Mash et al.,
in press). The fact that performance
remained poor in this condition
rules out these explanations of toddlers’
poor search performance. The
puppet study, which used looking
as the response rather than reaching,
found that 2-year-olds, like infants,
looked longer at the inconsistent
event (Mash et al., 2002). This
study rules out the disconcerting
possibility that infants are endowed
with knowledge about
physical events that gets lost during
development, and is regained
around 3 years of age. Finally, although
infants and toddlers both
fail in search tasks that require a
reaching response, previous work
not discussed here demonstrated
that 6-month-olds will reach for
objects hidden by darkness (Clifton,
Rochat, Litovsky, & Perris,
1991). Thus, it is not the response
of reaching, in contrast to looking,
that is the cause of infants’ and toddlers’
failure, but rather a problem
of knowing where to search.
What could be the toddlers’
problem in the search task? A distinct
possibility, already mentioned,
is the requirement of prediction.
In order to plan and execute
a successful search, toddlers had to
know the ball’s location in advance.
Moreover, they had to coordinate
this knowledge with appropriate
action. Further research is
needed to determine if either or
both of these aspects are critical. One
means of exploring this possibility
is to devise new tasks that require
location prediction but have fewer
spatial elements to be integrated
than the ball-barrier-door task and
require simpler action plans.
A second prime issue needing
further investigation is the relation
between gaze behavior and search.
Choice of the correct door was associated
with continuous gaze at
the hiding event; gaze breaks before
searching were fatal to success.
These data imply that children
did not use s ight of the
barrier’s top as a cue for the correct
door. Likewise, adults faced with
an array of 20 identical doors with
no further marker might well use
unbroken gaze at the point of disappearance
as a strategy. If confusion
among identical doors is the
children’s problem, then making
the doors distinct should help. This
manipulation coupled with careful
analysis of gaze could determine
whether the toddlers’ problem is
simply spatial confusion among
identical doors. If so, the interesting
question remains as to why the
barrier’s top does not cue location.
Finally, a theoretical issue is unresolved.
The results for the looking-
time task indicate that toddlers,
and even infants, have some
knowledge about the ball’s expected
location, but the contents of
their knowledge is unclear. According
to Spelke (Spelke et al.,
1992), the principles of continuity
and solidity are part of a constant
core of physical knowledge that infants
are endowed with. Infants of
3 to 4 months in age mentally represent
hidden objects and can reason
about an object’s motion being
constrained by continuity and solidity.
Spelke et al. (1992) did not
claim, however, that the infants in
their study could predict the ball’s
location, and the toddler data suggest
that infants’ and even 2-yearolds’
reasoning may be limited to
recognizing after-the-fact incongruent
events. If so, perceptual recognition
of implausible event outcomes
seems like a valuable building block
on which to construct further knowledge,
and eventually prediction,
about the physical world.
Recommended Reading
Bertenthal, B.I. (1996). Origins and
early development of perception,
action, and representation.
Annual
Review of Psychology
,
47
, 431–459.
Bremner, J.G. (1997). From perception
to cognition. In G. Bremner,
A. Slater, & G. Butterworth (Eds.),
Infant development: Recent advances
(pp. 55–74). Hove, England: Psychology
Press.
Spelke, E.S. (1991). Physical knowledge
in infancy: Reflections on
Piaget’s theory. In S. Carey & R.
Gelman (Eds.),
The epigenesis of
mind: Essays on biology and cognition
(pp. 133–169). Hillsdale, NJ:
Erlbaum.
Willatts, P. (1997). Beyond the “Couch
Potato” infant: How infants use
Copyright © 2003 American Psychological Society
CURRENT DIRECTIONS IN PSYCHOLOGICAL SCIENCE 83
their knowledge to regulate action,
solve problems, and achieve goals.
In G. Bremner, A. Slater, & G. Butterworth
(Eds.),
Infant development:
Recent advances
(pp. 109–135).
Hove, England: Psychology Press.
Acknowledgments—
This research was
supported by Grant HD27714 from the
National Institutes of Health and Research
Scientist Award MH00332 from
the National Institute of Mental Health to
Rachel K. Clifton (now Rachel Keen). I am
grateful to Neil Berthier, my collaborator
in all of these studies, and to the other collaborators
who contributed to various
phases of this work.
Note
1. Address correspondence to
Rachel Keen, Department of Psychology,
Tobin Hall, University of Massachusetts,
Amherst, MA 01003.
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