glish, Japanese, Hausa (a Nigerian language), and
sign language. Infants prefer motherese to adult-
directed speech, and they benefit from such interac-
tion. For example, by enhancing attention, mo-
therese promotes infants’ processing of speech.
Likewise, motherese helps infants to analyze the
structure of speech by highlighting boundaries be-
tween important units, such as words and clauses. Re-
search in the late 1990s suggested that motherese is
actually part of a more general tendency to modify
infant-directed interactions. For example, adults also
modify at least some of their infant-directed bodily
motions. Such ‘‘motionese’’ includes simplification
and increased repetition of action. Thus motherese
speech seems to be just one dimension of a whole con-
stellation of infant-directed modifications.
See also: BABBLING AND EARLY WORDS; LANGUAGE
DEVELOPMENT
Bibliography
Fernald, Anne, and Patricia Kuhl. ‘‘Acoustic Determinants of In-
fant Preference for Motherese Speech.’’ Infant Behavior and
Development 10 (1987):279–293.
Lieven, Elena. ‘‘Crosslinguistic and Crosscultural Aspects of Lan-
guage Addressed to Children.’’ In Clare Gallaway and Brian
Richards eds., Input and Interaction in Language Acquisition.
Cambridge, Eng.: Cambridge University Press, 1994.
Rebecca J. Brand
Dare A. Baldwin
MOTOR DEVELOPMENT
When babies are born, they are not able to move
much on their own. Over time, a baby learns to move
many parts of its body and control its muscles so it can
hold its head up, sit up by itself, stand up, or pick up
a toy. The process of motor development, however,
does not happen overnight. Like many things, learn-
ing about the body and making it move takes time.
Motor development is the process of learning how to
use muscles in the body to move. The progression of
acquiring motor skills goes from simple to complex.
Motor development happens in a predictable se-
quence of events for most children, but each child var-
ies in age when each skill is mastered. For example,
although most children begin to walk independently
around twelve to fourteen months, some children are
walking as early as nine months. Further, children
differ in terms of the length of time it takes to develop
certain motor skills, such as the baby who sits up, vir-
tually skips crawling, and begins walking.
Transition from Reflex Movement to
Voluntary Movement
At birth, babies have very little control over their
bodies. They spend most of their time curled up in
what is called a fetal position. This position is how the
baby lay in the womb during the nine months of the
mother’s pregnancy. In addition to the fetal position,
primitive reflexes dominate virtually all of a newborn
baby’s movements. Babies are born with these reflex-
ive movements as a means for basic life preservation.
The reflexes, which are controlled by lower levels of
the brain, eventually give way to more sophisticated
voluntary movements monitored by higher levels of
the brain.
The first voluntary task of a newborn is learning
to bring the arms and legs out straight in order to lie
flat. This maneuver takes a lot of muscular energy, so
the baby begins moving arms and legs around during
the waking hours to develop coordination and
strength. As babies move their bodies more in the first
months of life, motor pathways begin to form in the
brain. These pathways allow a baby to eventually per-
form motor movements without conscious thought.Principles of Development
The process of motor development depends
heavily on the maturation of the central nervous sys-
tem and the muscular system. As these systems devel-
op, an infant’s ability to move progresses. The
sequence of motor development follows an apparent-
ly orderly pattern. Arnold Gesell, a noted researcher
in the field of child development, indicated through
his studies that development does not proceed in a
straight line. Instead, it swings back and forth be-
tween periods of rapid and slower maturation. Gesell
and his colleagues also discovered from their infant
observations made in the 1930s and 1940s that infant
growth does indeed follow distinct developmental di-
rections: cephalocaudal, proximal-distal, and general
to specific.Cephalocaudal Principle
First, most children develop from head to toe, or
cephalocaudal. Initially, the head is disproportionate-
ly larger than the other parts of the infant’s body. The
cephalocaudal theory states that muscular control de-
velops from the head downward: first the neck, then
the upper body and the arms, then the lower trunk
and the legs. Motor development from birth to six
months of age includes initial head and neck control,
then hand movements and eye-hand coordination,
followed by preliminary upper body control. The sub-
sequent six months of life include important stages in
learning to control the trunk, arms, and legs for skills
such as sitting, crawling, standing, and walking.Proximal-Distal Principle
Second, children develop their motor skills from
the center of their bodies outward, near to far orMOTOR DEVELOPMENT 279