Running Head: PREHENSION ENRICHMENT EXPERIENCE
1
Prehension Enrichment Experience Facilitates Motor and Perceptual-Cognitive Development in
Early Infancy
Rachel Ballard
Thesis completed in partial fulfillment of the requirements of the Honors Program in
Psychological Sciences under the direction of Dr. Amy Needham
Vanderbilt University
April 2013
PREHENSION ENRICHMENT EXPERIENCE
2
Abstract
Infants received a prehension enrichment experience (active training), which allowed prereaching infants to gain experience with prehension before they would normally begin such
behaviors. During the prehension enrichment experience, infants received 10-14 ten-minute play
sessions wearing “sticky mittens”: mittens with palms covered in the loop side of Velcro,
allowing them to pick up small toys covered in Velcro hook. Two months after the enrichment
session, infants who received the prehension enrichment experience were compared with agematched peers who wore “non-sticky mittens” while observing their parents and the
experimenter manipulating objects (passive training). The results of this study indicate that two
months after the prehension enrichment experience, infants who received active training engaged
in more object exploration and exhibited accelerated reasoning about the support relations
between objects when compared to infants who received passive training. These results suggest
that early prehension enrichment experience facilitates the processes of object exploration and
engagement while also enhancing infants’ cognitive and perceptual development.
PREHENSION ENRICHMENT EXPERIENCE
3
Prehension Enrichment Experience Facilitates Motor and Perceptual-Cognitive Development in
Early Infancy
In the field of psychology, sensitive periods are a fascinating concept that explores the
influence of experience upon development. Sensitive periods are traditionally viewed as time
periods in which the organism is especially sensitive to environmental input. This environmental
influence is unidirectional and if present during the sensitive period, development will continue
along its designated trajectory. Other approaches acknowledge the interdependence of the
organism and its environment as well as the complex ways in which these interactions can
influence development. In this research, we explore how experience affects these interactions,
specifically examining the effects of prehension enrichment, which allows pre-reaching infants
to actively engage with objects through reaching and grasping. The effects of this experience on
infants’ object exploration and cognition were examined by comparing infants who received
active and passive training.
In 1953, Piaget suggested that the formation of action representation is aided by selfproduced action experiences (Piaget, 1953). Several recent studies have now shown that firsthand action experiences indeed influence infants’ perception and understanding of actions (Hauf,
2007; Sommerville & Woodard, 2005; Sommerville, Woodward, & Needham, 2005). Infants’
ability to identify the goal of an action is dependent on their ability and experience, whether
natural or artificial, in performing the same action (Sommerville & Woodard, 2005;
Sommerville, Woodward, & Needham, 2005). Overall, infants’ actions on objects seem to
increase their interest in not only their own actions, but also the actions performed by others on
the same object (Hauf, Aschersleben, & Prinz, 2007).
PREHENSION ENRICHMENT EXPERIENCE
4
How do infants’ new abilities build upon their existing abilities? Oftentimes, research in
development is criticized for failing to appreciate development as a dynamic, constantly
changing continuum that can be influenced by infant’s experiences and their ability to learn
through their own actions. As infants grow and develop, the interaction between their
environment and their behavior changes as they learn new information about the world around
them (Bushnell & Boudreau, 1993; Gibson, 1988). Manual exploration in infancy allows infants
to gain experience with a variety of sensory information, such as texture, color, shape, and
weight, from objects. (Lederman & Klatzky, 2009). As infants develop, object exploration
becomes increasingly multi-modal. Bi-manual exploration is linked to oral exploration in such a
way that multi-modal exploration later reappears as infants begin to simultaneously mouth and
finger objects. The development of sophisticated exploration techniques allows infants to
collection even more information about objects (Rochat, 1989). When infants engage in selfdirected manual exploration, they begin to develop advanced object segregation abilities
(Needham, 2000) and also attend to intermodal properties of objects (Eppler, 1995).
Accordingly, self produced movement and locomotion actively affects how infants respond and
interact with their environment (Bartenthal, Campos. & Kermoian, 1994; Clearfield, Osborne, &
Mullen, 2008). For example, when infants begin walking they engage in more social interaction
with their mothers and express more emotions (Clearfield, 2011). This finding suggests that
developing new motor skills may influence other areas of development (Biringen, Emde,
Campos & Applebaum, 1995). However, other studies, such as those presented by Adolph and
colleagues, demonstrate that learning from motor development can be very specific and does not
often generalize to novel situations (e.g., Adolph, 1997; Adolph, 2000; Adolph & Berger, 2006).
PREHENSION ENRICHMENT EXPERIENCE
5
As a result, it is not clear how infants’ motor learning experiences affect learning in other parts
of development.
Neurophysiological studies also suggest the involvement of motor development in action
observation and understanding. Recent research suggests that the mirror matching or mirrorneuron system (MNS) is a potential neurological basis for the relationship between action and
perception (Rizzolatti & Criaghero, 2004). Adult and infant studies have shown that action
experience and expertise modulate the response of the MNS (Cross, Hamilton & Grafton, 2006;
van Elk, Van Schie, Hunnius, Veser & Bekkering, 2008). In infancy, the MNS seems involved in
predicting the outcome of observed actions and events (Stapel, Hunnius, van Elk & Bekkering,
2010). Hence, the combination of behavioral and neurophysiological findings suggests that the
development of infants’ own motor abilities may influence their perception of people and
objects. Some research takes this hypothesis a step further by indicating that development in the
motor domain not only influences perception, but also facilitates development in the perceptualcognitive domains (Bushnell & Boudreau, 1993; Bertenthal et al., 1994; Gotlieb, 1991).
Accordingly, certain perceptual or cognitive milestones cannot be achieved until appropriate
motor development has taken place. Thus, the acquisition of motor abilities allows for
development in the perceptual and cognitive domains.
In conversation with this idea, researchers began investigating specific aspects of infants’
perceptual and cognitive development, such as infants’ ability to reason about support relations
between objects (Baillargeon and Hanko-Summers, 1990; Needham & Baillargeon, 1991;
Needham & Baillargeon, 1997; Spelke, et al., 1991). These experiments used a simple object
support task, which included two objects: a small box and a larger, more stable platform
underneath. Three situations could be displayed with respect to these objects: (1) the box could
PREHENSION ENRICHMENT EXPERIENCE
6
rest fully on the platform (full-contact event); (2) the box could rest only partially on the
platform (partial-contact event); and (3) the box could be in mid-air, entirely off the platform
(no-contact event).
One experiment examined 4.5-month infants’ responses to a full-contact and a no-contact
events (Needham and Baillargeon, 1997). For the full-contact event, a gloved hand deposited the
box on the platform and then retreated a short distance. This left the box supported by the
platform. For the no-contact event, the hand deposited the box beyond the platform, and then
retreated, leaving the box suspended in mid-air with no apparent means of support. Infants in the
study looked significantly longer at the no-contact than the full-contact event suggesting that
they expected the box to fall when it was released and were surprised that it did not. The findings
from this study together with those of control experiments indicate that 4.5-month infants, like
adults, realize that objects cannot remain stable without support.
Another experiment indicated that 3-month infants hold the same belief about object
support (Needham & Baillargeon, 1991). The infants in this experiment were also shown a fullcontact and a no-contact event. The infants again looked significantly longer at the no-contact
than the full-contact event, suggesting that they expected the box to fall when it was pushed off
the platform and were surprised that it did not. Overall, the results of this experiment and the
control condition indicated that by 3 months of age, infants expect a box to remain stable when it
is in full contact with a platform, and to fall when it loses all contact with the platform.
Further research examined at what age infants begin to distinguish between partial and
full-contact events. In this experiment, 6.5-month infants saw two test events: a full-contact and
a partial-contact test event. In both events, the infants watched the extended finger of a gloved
hand push a box along the top of a platform. In the full-contact event, the box was pushed until
PREHENSION ENRICHMENT EXPERIENCE
7
its leading edge reached the end of the platform. In the partial-contact event, the box was pushed
until only 15% or 70% of its bottom surface remained on the platform. The results suggested
that the infants were able to determine how much contact was needed between the box and the
platform for the box to be stable. In a second experiment, 5.5-6.5 month infants were found to
look equally at the full and the partial-contact events even when only 15% of the box’s bottom
surface remained on the platform. This result further suggested that prior to 6.5 months of age
infants perceive any amount of contact between the box and the platform to be sufficient to
ensure the box’s stability (Baillargeon, Needham, & DeVos, 1992).
Overall, infants from 3 to 6.5 months of age have various levels of reasoning about
support relations. By 3 months of age, infants have formed an initial concept of support centered
on simple contact/no-contact distinction; they expect the box to remain stable if released in
contact with the platform and to fall otherwise. At this stage, any contact with the platform is
sufficient to ensure the box’s stability. In the months to follow, infants identify a sequence of
variables that progressively revise and elaborate this initial concept. At about 4.5 to 5.5 months
of age, infants begin to take into account the type of contact between the box and the platform.
Infants expect the box to remain stable when released on, but not against the platform. At
around 6.5 months of age, infants begin to consider the amount of contact between the box and
the platform. Infants now expect the box to remain stable only if over half of its bottom surface
rests on the platform.
The purpose of the current research is to: examine the influence of motor development
upon development in perceptual-cognitive domains, identify the key component of prehension
enrichment experience, and examine the long-term effects of prehension enrichment. While it is
possible that no long-term effects exist from prehension enrichment, it is also possible that
PREHENSION ENRICHMENT EXPERIENCE
8
infants could experience increased object exploration and object engagement, facilitating infants
perceptual-cognitive development in the areas of object segregation, object accessibility, and
infants overall understanding of the physical world.
Original Study
In a study completed by Needham, Barrett, and Peterson in 2002, infants received a
prehension enrichment experience, which allowed pre-reaching infants to gain experience with
prehension before they would normally begin such behaviors. The analysis of this study focused
on reaching and grasping behaviors, two important developmental milestones that enable infants
to obtain objects for further inspection on their own. Despite earlier reports of reaching in
newborns, (Bower, Broughton, and Moore, 1970), most of the time newborns do not succeed in
contacting or obtaining objects with their pre-reaching attempts (von Hofsten, 1982). Successful
independent reaching does not emerge until about 4-5 months after birth (Pomerleau & Malcuit,
1980; von Hofsten & Ronnqvist, 1988). Therefore, this study tested 3-month-old infants who
were not yet able to reach for an object independently. During the prehension enrichment
experience, infants received 10-14 ten-minute play sessions wearing “sticky mittens”: mittens
with palms covered in the loop side of Velcro, allowing them to pick up small toys covered in
Velcro hook. After the enrichment sessions (two weeks after the initial visit), the experienced
infants’ object engagement and object exploration skills were compared to infants who were the
same age and had not received the play sessions. The results of the study suggested that the
experienced infants showed more object engagement and more sophisticated object exploration
than their inexperienced peers.
Although the results of this study showed significant differences between experienced
and inexperienced infants, this research alone is not able to identify what exactly about the
PREHENSION ENRICHMENT EXPERIENCE
9
enrichment experience aided in the facilitation of these object exploration skills. One possibility
is that by noticing the contingency between their own movements and the consequence of those
movements for moving and transporting objects caused the observed behavior changes.
Alternatively, the critical component of the experience could have been the additional practice
infants received with objects, such as the parent bringing objects to the infant’s face for visual
exploration or to the infant’s mouth for oral exploration. If this is the case, experiences in which
the parent placed objects in the infant’s hands should also be effective. The experience may
have also been performed in a more systematic fashion than it typically would have in
comparison to infant’s typical daily experiences. Accordingly, infants tested in the same fashion
without mittens would show similar effects. Finally, it may have been the experience of mittens
on their hand that drew infants’ attention to their hands and led to behavioral changes. If mittens
are the key component to this enrichment, the stickiness of the mittens is not essential, and
infants wearing mittens without Velcro should experience the same enrichment (Needham,
Barrett, and Peterson, 2002).
Current Study
The current study expands on the research of Needham and colleagues (2002) by
identifying the key component of the prehension enrichment experience as well as examining the
long-term effects of the experience upon motor and perceptual-cognitive development in infancy.
Methods
Participants. Twenty-five healthy full term infants, between 2.5 and 3-months of age
participated in the study (14 males, 11 females). The mean age for participants was 2 months, 21
days (SD=8.5 days; age=2 months, 14 days to 3 months, 0 days). Infants were included in either
the “Active Training”(AT) or “Passive Training”(PT) groups. The AT group consisted of 15
PREHENSION ENRICHMENT EXPERIENCE
10
infants (M=2 months, 20 days; 9 males, 5 females) who were trained using “Sticky Mittens” for
approximately 2 weeks. The PT group consisted of 10 infants (M=2 months, 22 days; 5 males, 5
females) who observed their parent grasp and move objects for approximately 2 weeks. A
summary of participant characteristics can be found in Table 1. Data from an additional 8 infants
were collected and excluded, 3 because infants were not compliant and did not complete all three
study visits, 2 because infants did not complete the study due to excessive fussiness at multiple
visits, 2 because infants were not in the appropriate age, and 1 because the infant did not
complete the study due to excessive sleepiness at multiple visits. The infants who participated in
this study were recruited from the birth records of the state of Tennessee. Parents were contacted
via telephone and did not receive compensation for their participation.
Stimuli.
Sticky mittens. Custom-made infant mittens with Velcro (loop) sewn to the palm (“Sticky
Mittens”, see Needham et al., 2002) were placed on infants hands during training in the AT
groups (Figure 1).
Non-Sticky mittens. Custom-made infant mittens modeled after “Sticky Mittens” were
created with strips of plain fabric, which replaced the Velcro strips sewn to the palm, making
them appear visually similar to the “Sticky Mittens” (Figure 1). These mittens were placed on
infants hands during training in the PT groups.
Training Toys. A set of six Duplo blocks was used as training toys in both the AT and
the PT group. Blocks measure 4.5 cm on each side with a 2.5 cm round dome on top. For the AT
group, small squares of Velcro hook were attached to the blocks making them stick to the
mittens. For the PT group, small squares of electrical tape were attached to the blocks, making
PREHENSION ENRICHMENT EXPERIENCE
11
them appear visually similar to the blocks used in the AT group; the blocks would not stick to
these PT group’s mittens upon contact.
Procedure.
Laboratory Sessions.
Session 1. Infants in both the experimental and control conditions participated in this
portion of the study. This laboratory session consisted of two kinds of trials: the prehension
trials and the object exploration trials. The prehension trials featured objects that would be used
in the active and passive training sessions. Infants wore their respective mittens for each of these
trials. During these prehension trials, infants’ visual contact with the objects on the table and
how much they swiped at these objects was examined. On the other hand, the object exploration
trials were designed to assess infants’ object exploration skills, and featured novel objects.
These trials attempted to investigate infant’s visual and oral exploration of objects.
During the prehension trials, the infant sat on a parent’s lap in front of a wooden table
69.85 cm in height with a tabletop that was 177.80 cm from left side to right side and 73.66 cm
from the participant to the experimenter. The experimenter sat across the table from participant.
The table was crescent moon shaped and oriented in such a way that the table surrounded the
participant on three sides. Four video cameras filmed the procedure from different perspectives:
One camera was mounted directly behind the experimenter, another camera was mounted on the
ceiling above the table, and two cameras were mounted on the side walls—one capturing the
right side and one the left side. These cameras were able to capture the infant’s face and hand
motions from the front, above, and both sides. The experimenter placed Duplos, one at a time, in
front of the infant. The infant was then allotted approximately 2 minutes to interact with these
objects and this behavior was recorded. If the infant became inattentive to the objects or the
PREHENSION ENRICHMENT EXPERIENCE
12
experimenter, the experimenter tapped lightly on the table or moved the objects slightly to
reorient the infant.
Following the prehension trials, which allowed the infant to become accustomed to the
mittens, the experimenter moved to the object exploration trials, which repeated the procedure of
the prehension trials giving the researchers a baseline for how infants played with the mittens
prior to AT or PT.
Session 2. The second laboratory session took place two weeks after the first laboratory
session. It was during this time infants received their Active Training (Length of AT Mean = 112
min) or Passive Training (Length of PT Mean = 124 min), infants again participated in the
prehension trials and the object exploration trials. The prehension trials featured objects that had
been used in the active and passive training sessions. Infants wore their respective mittens for
the prehension trials, but not for the object exploration trials. In addition to these trials, the
infants also received a four-step reaching assessment (without wearing mittens), where a toy was
sequentially placed beyond reach, far, but within reach, next to the hand, and finally placed into
the infant’s hand (Figure 2). If the infant dropped the toy immediately, up to three further
attempts were made to place the toy into the infants’ hand. The four steps were always
performed in the same order (Beyond, Far, Close, In Hand) and each step lasted approximately
30 second before the experimenter moved on to the next step.
Session 3. In the third laboratory session, which took place two months after the second
laboratory session, infants again received the four-step reaching assessment. In addition, they
also received a simple object support task. During this task, infants saw two test events: an
adequate support event and an inadequate support event. In both events, infants watched a hand
place a box on top of a platform. In the adequate support event, the box was placed on top of the
PREHENSION ENRICHMENT EXPERIENCE
13
platform, with 70% of its bottom surface remaining on the platform. In the inadequate support
event, the box was placed on top of the platform, with 15% of its bottom surface remaining on
the platform.
Coding. Infants’ motor behavior was coded by trained observers using frame-by-frame
coding software (Libertus, 2008). The following behaviors were assessed: looking at the toy or
the experimenter or elsewhere, reaching for the toy (extending hand toward the toy regardless of
intention or gaze), touching the toy, grasping the toy (holding the toy), bi-manual exploration,
lifting (touching the toy and bringing all corners of the toy off the table) and mouthing the toy.
Two different observers coded a random sample of trials from all three visits using frame-byframe coding software and overall reliability was high (r = .80).
Results
The results from this study will focus on the analysis of the third visit data, which was
collected two months after the training ended. The data from the first two visits corroborates the
data from the original study and thus, does not contribute new insights into the current research.
No effects of gender or order were found in this study. A series of independent t-tests were
conducted to compare looking, reaching, grasping, bilateral exploration, lifting, and mouthing in
both the AT and PT conditions across the four-step reaching assessment.
In Step 1 (Beyond) of this assessment, there was a significant difference in the amount of
time spent looking at the object between infants with AT (M = 15.15, SD = 6.88) and infants
with PT (M = 6.53, SD = 3.41) condition: t(17) = 2.11, p < .01. There was also a significant
difference in the amount of time in which infants were distracted between infants with AT (M =
6.72, SD = 4.75) and infants with PT (M = 11.74, SD = 4.77); condition t(35) = 2.03, p < .01.
These findings suggest that infants with AT are engaging in more visual exploration of objects
PREHENSION ENRICHMENT EXPERIENCE
14
even when the object is inaccessible, while infants with PT are more distracted when the object
is inaccessible (Figure 3).
During Step 2 (Far) and Step 3 (Close), there was still a significant difference in the
amount of time spent looking at the object between infants with AT (M = 22.94, SD = 5.78) and
infants with PT (M = 15.27, SD = 7.77) condition: t(35) = 2.03, p < .01. There was also a
significant difference in the amount of time in which infants were distracted between infants with
AT (M =3.94, SD = 4.88) and infants with PT (M = 8.39, SD = 5.88); condition t(37) = 2.03, p <
.01. Accordingly, infants with AT still looked significantly more at the object, than infants with
PT, who were still significantly more distracted. In addition, there was a significant difference in
the amount of time spent grasping the object between infants with AT (M = 16.72, SD = 12.18)
and infants with PT (M = 8.37, SD = 11.24); condition t(42) = 2.02, p = .02 as well as the amount
of time spent bilaterally exploring the object between infants with AT (M = 10.78, SD = 8.56)
and infants with PT (M = 5.65, SD = 8.05); condition t(39) = 2.02, p = .04) (Figure 4). This
suggests infants with AT spent significantly more time grasping and bilaterally exploring the
object, than infants with PT, indicating that the effects of increased object exploration and
engagement found in Needham, et al., 2002 are maintained up to two months after the initial
training is complete. It is also important to realize that at the third visit, the average age of
infants is (M= 5 months, 8 days), which implies that these results do not indicate whether or not
it is possible for infants to reach for the object (as was likely the case in Needham, et al., 2002)
because all infants at this age should be able to engage in self-directed reaching behavior. These
findings suggest that the motor development of infants with AT remains a step ahead of the
motor development of infants with PT, because infants with AT develop more advanced
strategies for exploring objects.
PREHENSION ENRICHMENT EXPERIENCE
15
Throughout Step 4 (In Hand), there was again a significant difference in the amount of
time spent looking at the object between infants with AT (M = 25.59, SD = 4.50) and infants
with PT (M = 14.92, SD = 9.25) condition: t(13) = 2.16, p < .01. There was also still a significant
difference in the amount of time in which infants were distracted between infants with AT (M
=2.15, SD = 1.58) and infants with PT (M = 7.54, SD = 5.34); condition t(25) = 2.06, p < .01.
However, there was not a significant difference in the reaching, touching, grasping, mouthing,
lifting, and bilateral exploration between infants with AT and infants with PT during this trial (all
t’s< .62). This may indicate that infants with AT, overall, spend more time exploring both
visually and manually than infants with PT. Infants with PT, although capable of reaching in
Step 2 and 3, only reached the level of exploration that infants with AT achieved in Step 2 and
Step 3, when the object was placed directly into their hand (Step 4). Infants with AT seem to
maintain a high level of exploration throughout the four-step reaching assessment further
suggesting that infants with AT maybe stay a step ahead of infants with PT as they continue to
develop manual skills for learning about objects.
A series of independent t-tests as well as, One-way Analysis of Variance (ANOVA),
were conducted to compare looking across the object support task. This revealed that there was
a significant Order (inadequate support event first, or adequate support event first) x Type of
Training (AT/PT) Interaction F(1, 44) = 5.36, p = .03. We then examined looking time at the
specific test events: the inadequate support event and the adequate support event. There was a
significant difference in the amount of looking time at the inadequate support event between
infants with AT (M = 7.16, SD = 4.05) and infants with PT (M = 3.46, SD = 3.96); condition
t(21) = 2.25, p < .01, specifically when infants with AT viewed the inadequate support event first
(Figure 5). There was also a significant difference in the amount of looking time at the adequate
PREHENSION ENRICHMENT EXPERIENCE
16
support event between infants with AT (M = 6.62, SD = 3.97) and infants with PT (M = 3.41, SD
= 4.01); condition t(24) = 2.64, p < .01 specifically when infants with AT viewed the inadequate
support event first. These findings demonstrate that infants with AT looked significantly longer
than infants with PT at the inadequate support and adequate support events when they saw the
inadequate support event first. Infants with PT did not look significantly longer at either the
inadequate support or the adequate support event regardless of which came first. Planned
comparison analysis also indicates that infants with AT, who viewed the inadequate support
before the adequate support event looked significantly longer at both events (inadequate support
event M = 7.16; adequate support event M = 6.62) than did the infants with PT (inadequate
support event M = 3.46; adequate support event M = 3.97), F(1,44) = 68.66, p < .01.
Discussion
In the original study completed by Needham, Barrett, and Peterson in 2002, the results
were not able to identify what exactly about the enrichment experience facilitated the
development of object exploration and object engagement in AT infants. Several possibilities
include: infant’s realization of the contingency between their own movements (reaching) and the
consequence of their actions (grasping), the additional practice infants receive with objects, such
as the parent bringing objects to the infant’s face for visual exploration or to the infant’s mouth
for oral exploration, and the experience of mittens on their hand that drew infants’ attention to
their hands. The results of the current study indicate that neither the additional practice infants
receive with objects (Length of AT Mean = 112 min or Length of PT Mean = 124 min), or the
experience of having mittens on their hands, (infants in both AT and PT wear mittens) are
significant in contributing to the development of infant’s object exploration and object
engagement. This suggests that the use of “Sticky Mittens” in the prehension enrichment
PREHENSION ENRICHMENT EXPERIENCE
17
experience allows infants with AT to engage in self-directed reaching, which promotes infant’s
conceptualization of the contingency between their own movements (reaching) and the
consequence of their actions (grasping), thus influencing their perceptual-cognitive development.
Previous research indicates that the development of infants’ motor abilities may facilitate
development in the perceptual-cognitive domains (Bushnell & Boudreau, 1993; Bertenthal et al.,
1994; Gotlieb, 1991). Accordingly, certain perceptual or cognitive milestones cannot be
achieved until appropriate motor development has taken place. Thus, the acquisition of motor
abilities allows for development in the perceptual and cognitive domains. The results of the
current study provide support for this view of development by suggesting that prehension
enrichment experience (AT) allows pre-reaching infants to actively engage with objects through
reaching and grasping, thus facilitating their early motor development. Two months after the
prehension enrichment experience infants with AT still displayed significantly more visual and
manual attention to objects, engaging in complex object engagement patterns such as bilateral
exploration, than infants with PT.
Furthermore, the results of this study suggest that the prehension enrichment experience
also facilitates accelerated reasoning about the support relations between objects in infants with
AT. As mentioned previously, infants begin to consider the amount of contact between the box
and the platform at around 6.5 months of age. These infants expect the box to remain stable only
if over half of its bottom surface rests on the platform. In another experiment, 5.5-6.5 month
infants were found to look equally at full and partial-contact events even when only 15% of the
box’s bottom surface remained on the platform. This result further suggested that prior to 6.5
months of age infants perceive any amount of contact between the box and the platform to be
sufficient to ensure the box’s stability (Baillargeon, Needham, & DeVos, 1992). However, the
PREHENSION ENRICHMENT EXPERIENCE
18
mean age for infants in the 3rd visit of the present study is (M = 5 months, 8 days) and the mean
age for infants with AT is (M = 5 months, 7 days). This indicates that infants with AT have
developed an advanced understanding of object support relations in comparison to their age, as
seen by the fact that they are significantly discriminating between the inadequate support event
(15% of the box’ bottom surface remains on the platform) and the adequate support event (70%
of the box’s bottom surface remains on the platform). For infants with AT, perhaps viewing the
inadequate support event first provides such a salient, abstract experience, that it severely
conflicts with the infant's previous experience (according to AT and what they have experienced
in life). Consequently, the infant is surprised which promotes a heightened state of attention,
thereby more effectively engaging the infant throughout the rest of the task. This explains why
when infants with AT view the inadequate support event first, they still look significantly more
at the adequate support event. For infants with AT, who view the adequate support event first,
this display is in accordance with their previous experience and therefore, they never reach the
same state of heightened engagement in the task as infants with AT who, first, view the
inadequate support event. Another explanation may indicate that infants are not able to process
the change between the inadequate support event and adequate support contact event. During
object support studies such as the study completed by Baillargeon, Needham, & DeVos in 1992,
the inadequate support and adequate support events were shown on a puppet stage apparatus that
had a curtain that closed in between trials. The occlusion of the entire display may have
prompted infants to re-examine the display in a way that the procedure we used did not.
Additionally, infants with PT do not look significantly more at either display, suggesting that AT
directly facilitates the accelerated reasoning seen in infants with AT about the support relations.
PREHENSION ENRICHMENT EXPERIENCE
19
Limitations of the Research.
The main limitation of this research is that it does not control for the possibility that
parents influence the way their infants interact with objects. By participating in this study,
parents attention could have been drawn to how their infant interacts with objects, thus during
the 2 months between the second and third visit parents may be engaging their infant in object
directed behaviors; however, there is no data to suggest that this effect is present in the current
study. Also, it is important to note that the findings of this study were found in participants who
are mostly of Caucasian ethnicity and have a high socio-economic status.
Conclusion
A wide variety of effects may be produced by infants’ increased object engagement and
exploration. If as infants explore objects more actively and objectively, they learn about the
relationship between object features and object boundaries, they could be learning how to
effectively distinguish object boundaries, by examining abrupt changes in an object’s shape,
color, and pattern. Infants with AT should have advanced exploration skills, and, as a result
advanced object segregation skills.
Future research will examine if there are other aspects of development, which the
prehension enrichment experience has advanced or affected. Prehension enrichment experience
may also allow infants to perform object categorization or problem solving tasks earlier than
their peers, or impacts areas of executive function such as attention, inhibition, or working
memory. This research will also strive to determine the duration of prehension enrichment
experience effects. The prehension experience may also serve as an intervention for infants who
have motor development deficits, which could impede their later cognitive development.
PREHENSION ENRICHMENT EXPERIENCE
20
The findings provide a glimpse into the processes underlying the development of motor
abilities; specifically, they suggest that self-directed experience acting on objects is an important
contributor to infants’ reasoning about object support relations that are typically observed around
6.5 months of age. When infants receive the prehension enrichment experience, their ability to
understand the relations of support between objects is accelerated and enhanced, highlighting the
relationships between early motor development and perceptual-cognitive development. Future
work will provide a better understanding of this relationship as infants develop during their first
year of life.
Acknowledgements
I wish to thank my honors thesis mentor Dr. Amy Needham for her guidance and support
throughout this project. In addition, I would like to thank the lab managers, research assistants,
and graduate students working in the Infant Learning Lab at Vanderbilt University for their
assistance in recruitment, coding, and running the study. Finally, I would to like to thank Dr.
Leslie Kirby, co-director of the undergraduate honors program in psychology.
PREHENSION ENRICHMENT EXPERIENCE
21
Table 1
Summary of Participant Characteristics
Group
n
#
Race
F
AT
15
6
Training
Age V1
Age V2
Age V3
duration
13W,
Parent
Birth
edu.
weight
112(1.32)
2.67(.34)
3.17(.16)
5.20(.21)
9.07(2.34)
3648(462)
124(1.24)
2.73(.23)
3.30(.18)
5.90(.23)
9.9(1.45)
3403(339)
1B,
1M
PT
10
5
10W
Note: The total number of participants in each group (n) and the number of females per group
(#F) are indicates. All other values are group averages with standard deviations given in
parentheses. Age is reported in months, with the days as a decimal, birth weight in grams,
training duration in minutes, Parent’s education level was assessed on a scale from 0 (no High
School degree) to 6 (Post-doctoral training) for each parent and summed (max. 12). Race
abbreviations: C = Caucasian, B = Black or African American, A = Asian, M = More than one.
PREHENSION ENRICHMENT EXPERIENCE
22
Figure Captions
Figure 1. An example of active and passive training procedures. (a) active training (AT); toys
stick to the mittens upon contact and are moved by the infant. (b) passive training (PT); toys are
moved by the parent and do not stick to the mittens. This figure was duplicated from (Libertus &
Needham, 2010).
Figure 2. An example of the four-step reaching assessment. A small toy was sequentially placed
(1) beyond reach, (II) far but within reach, (III) close to hands at midline, and (IV) place into the
infants hands. Each step lasted about 30 s. The test was completed once during the second and
third lab visit. This figure was duplicated from (Libertus & Needham, 2010).
Figure 3. Comparison of mean looking at object across the four-step reaching assessment.
Figure 4. Comparison of mean grasping and bilateral exploration across the four-step reaching
assessment.
Figure 5. Comparison of mean looking during inadequate and adequate support events.
PREHENSION ENRICHMENT EXPERIENCE
Figure 1.
23
PREHENSION ENRICHMENT EXPERIENCE
Figure 2.
24
PREHENSION ENRICHMENT EXPERIENCE
25
Mean Looking Time at Object Across FourStep Reaching Assessment
35
30
25
Time (s)
Passive Training (PT)
20
Active Training (AT)
15
10
5
0
Step 1 - Beyond
Figure 3.
Step 2 & 3 - Far &
Close
Step 4 - In Hand
PREHENSION ENRICHMENT EXPERIENCE
26
Mean Time Grasping and Exploring
Bilaterally Across Four-Step-Reaching
Assessment
20
18
16
Time (s)
14
Passive Training (PT)
12
10
8
Active Training (AT)
6
4
2
0
Grasping
Figure 4.
Bilateral Exploration
PREHENSION ENRICHMENT EXPERIENCE
27
Mean Looking Times During Inadequate
& Adequate Support Events
14
12
Time (s)
10
8
Inadequate
6
Adequate
4
2
0
Passive
Figure 5.
Active
PREHENSION ENRICHMENT EXPERIENCE
References
Adolph, K. E. (1997). Learning in the development of infant locomotion. Monographs
of the Society for Research in Child Development, 62(3), I-VI, 1-158.
Adolph, K. E. (2000). Specificity of learning: Why infants fall over a veritable cliff.
Psychological Science, 11(4), 290–295.
Adolph, K. E. & Berger, S. E. (2006). Motor Development. In D. Kuhn & R. S. Siegler
(Eds.), Handbook of child psychology: Vol 2. Cognition, perception, and language (6th
ed., pp. 161-213). New York: Wiley.
Baillergeon, R. & Hanko-Summers, S. (1990). It’s the top object adequately support by the
bottom object? Young infants understanding of support relations. Cognitive
Development, 5, 29-33.
Baillergeon, R., Needham, A., and DeVos, J. (1992). The development of young infants’
intuition about support. Early Development and Parenting. 1(2), 69-78.
Bertenthal, B. I., Campos, J. J., & Kermoian, R. (1994). An epigenetic perspective on
the development of self-produced locomotion and its consequences. Current
Directions in Psychological Science, 3(5), 140–145.
Biringen, Z., Emde, R. N., Campos, J. J., & Appelbaum, M. I. (1995). Affective
reorganization in the infant, the mother, and the dyad – The role of upright
locomotion and its timing. Child Development, 66(2), 499–514.
Bower, T. G. R., Broughton, J. M., & Moore, M. K. (1970). Demonstration of intention
in reaching behaviour of neonate humans. Nature, 228(5272), 679–681.
Bushnell, E. W., & Boudreau, J. P. (1993). Motor development and the mind – The
potential role of motor abilities as a determinant of aspects of perceptual
28
PREHENSION ENRICHMENT EXPERIENCE
development. Child Development, 64(4), 1005–1021.
Clearfield, M. W. (2011). Learning to walk changes infants’ social interactions.
Infant Behavior & Development, 34(1), 15-25.
Clearfield, M. W., Osborne, C. N., & Mullen, M. (2008). Learning by looking: Infants’
social looking behavior across the transition from crawling to walking. Journal
of Experimental Child Psychology, 100(4), 297–307.
Cross, E. S., Hamilton, A. F., & Grafton, S. T. (2006). Building a motor simulation de
novo: Observation of dance by dancers. Neuroimage, 31(3), 1257–1267.
Eppler, M. A. (1995). Development of manipulatory skills and the deployment of attention.
Infant Behavior and Development, 18(4), 391–405.
Gibson, E. J. (1988). Exploratory behavior in the development of perceiving, acting
and acquiring of knowledge. Annual Review of Psychology, (39), 1–41.
Gottlieb, G. (1991). Experiential canalization of behavioral development: Theory.
Developmental Psychology, 27, 4–13.
Hauf, P. (2007). Infants’ perception and production of intentional actions. In C.
Hauf, P., Aschersleben, G., & Prinz, W. (2007). Baby do-baby see!: How action
production influences action perception in infants. Cognitive Development, 22(1),
16–32.
Lederman, S. J., & Klatzky, R. L. (2009). Haptic perception: A tutorial. Attention
Perception & Psychophysics, 71(7), 1439–1459.
Libertus, K. (2008). Stop Frame Coding (Version 0.9) [Coding Software]. Durham, NC.
Libertus, K. & Needham, A. (2010). Teach to reach: The effect of active vs. passive
reaching experiences on action and perception. Vision Research, 50(24), 2750-2757.
29
PREHENSION ENRICHMENT EXPERIENCE
30
Needham, A. (2000). Improvements in object exploration skills may facilitate the development
of object segregation in early infancy. Journal of Cognition and Development, 1(2), 131–
156.
Needham, A. & Baillargeon, R. (1997). Reasoning about support in 3-month-old infants.
Manuscript under revision.
Needham, A. & Baillargeon, R. (1991). Intuition about support in 4.5-month-old infants.
Cognition. 47, 121-149.
Needham, A., Barrett, T., & Peterman, K. (2002). A pick-me-up for infants’ exploratory skills:
Early simulated experiences reaching for objects using ‘sticky mittens’ enhances young
infants’ object exploration skills. Infant Behavior and Development, 25(3), 279–295.
Piaget, J. (1953). The origin of intelligence in the child. New York: Routledge and
Kegan Paul Ltd.
Pomerleau, A., & Malcuit, G. (1980). Development of cardiac and behavioral
responses to a 3-dimensional toy stimulation in 1-month to 6-month-old
infants. Child Development, 51(4), 1187–1196.
Rizzolatti, G., & Craighero, L. (2004). The mirror-neuron system. Annual Review of
Neuroscience, 27, 169–192.
Rochat, P. (1989). Object Manipulation and Exploration in 2- to 5-Month-Old Infants.
Developmental Psychology, 25(6), 871-844.
Sommerville, J. A., & Woodward, A. L. (2005). Pulling out the intentional structure of
action: The relation between action processing and action production in
infancy. Cognition, 95(1), 1–30.
Sommerville, J. A., Woodward, A. L., & Needham, A. (2005). Action experience alters
PREHENSION ENRICHMENT EXPERIENCE
3-month-old infants’ perception of others’ actions. Cognition, 96(1), B1–11
Spelke. E., Breinlinger, K., Macomber, J., Turner, A., and Keller, M. (1991). Origins of
knowledge. Psychological Review. 99(4), 605-632.
Stapel, J. C., Hunnius, S., van Elk, M., & Bekkering, H. (2010). Motor activation during
observation of unusual vs. ordinary actions in infancy. Social Neuroscience.
van Elk, M., van Schie, H. T., Hunnius, S., Vesper, C., & Bekkering, H. (2008). You’ll
never crawl alone: Neurophysiological evidence for experience-dependent
motor resonance in infancy. Neuroimage, 43(4), 808–814.
von Hofsten, C. (1982). Eye-hand coordination in the newborn. Developmental
Psychology, 18(3), 450–461
von Hofsten, C., & Ronnqvist, L. (1988). Preparation for grasping an object – A
developmental-study. Journal of Experimental Psychology-Human Perception and
Performance, 14(4), 610–621.
31