chapter
5
Early Motor
Development
Early Motor Behavior
• Can be reflexive or spontaneous (Clark,
1995)
• Reflexive: stereotypical response elicited by
a specific external stimuli
• Spontaneous: movements not caused by
known external stimuli
Spontaneous Behaviors
• Assumed to be extraneous movements with
no purpose
• Similar to “mature” movements
• Examples
– Spontaneous arm movements and reaching
– Spontaneous kicking and adult walking
Infant Kicks
Click image to view video
Reflexes
• Reflexes occur quickly after onset of
stimuli.
• They involve a single or specific group of
muscles (not the whole body).
• They resist habituation (at any one time).
• Persistence may indicate neurological
problems.
Purpose of Reflexes
• Built-in responses facilitate survival.
• They enable open dialogue with the
environment.
• Reflexive movements result in sensory
consequences (adaptation).
• Reflexes provide building blocks for future
movement.
Asymmetrical Tonic Neck Reflex
• Infant starts in supine
position.
• Stimulus: turn head to
one side.
• Response: same-side
arm and leg extend.
Symmetrical Tonic Neck Reflex
• Infant starts in supported sitting.
• Stimulus: extend head and neck or flex
head and neck.
• Response: arms extend and legs flex, or
arms flex and legs extend.
Palmar Grasp Reflex
• Stimulus: touch palm with finger or object.
• Response: hand closes tightly around
object.
Moro Reflex
• Infant starts in supine
position.
• Stimulus: shake head
(e.g., by tapping
pillow).
• Response: arms, legs,
and fingers extend;
then arms and legs
flex.
Stepping Reflex
• Stimulus: place soles
of feet on flat surface.
• Response: walking
pattern of legs.
More Reflexes
Sucking reflex
Babinski reflex
• Stimulus: touch face
above or below the
lips.
• Stimulus: stroke sole
of foot from heel to toe.
• Response: toes extend.
• Response: sucking
motion begins.
Constraints
What constraints exist during the reflexive
period?
–
–
–
–
–
Structural
Functional
Environmental physical
Environmental sociocultural
Task: goals, rules, equipment
Later Infancy
• Gain voluntary control of movements
• Understanding of environment, objects in
the environment
• Meaningful interactions with others
• Postural reactions
Postural Reactions
• Begin at around 4 months
• Help to maintain posture in a changing
environment
• Initially, similar to reflexes; later,
incorporated into general repertoire
Labyrinthine Righting Reflex
• Infant is supported
upright.
• Stimulus: tilt infant.
• Response: head moves
to stay upright.
More Postural Reactions
Derotative righting
Parachute
• Infant starts in supine
position.
• Infant held upright.
• Stimulus: turn head to one
side, or turn legs and pelvis
to other side.
• Stimulus: lower infant
toward ground rapidly.
• Response: body follows
head in rotation, or trunk
and head follow in rotation.
• Response: legs and
arms extend.
Motor Milestones
• Fundamental motor skills
– Building blocks
– Cumulative, sequential
– Lead to future complex motor skills
• Specific movements that lead to general
actions
Locomotor and Posture Motor
Milestones: An Example
Emily at 2 months
(continued)
Locomotor and Posture Motor
Milestones (continued)
• 2 months: lifts
head in prone
• 3 months: lifts
shoulders (turns
head)
(continued)
Locomotor and Posture Motor
Milestones (continued)
• 5 months: rolls
over; sits
unsupported
(continued)
Locomotor and Posture Motor
Milestones (continued)
• 7 months: gets
on hands and
knees
• 8 months: creeps
on hands and
knees
(continued)
Locomotor and Posture Motor
Milestones (continued)
• 9 months:
pulls to stand;
cruises
furniture
(continued)
Locomotor and Posture Motor
Milestones (continued)
• 10 months:
stands alone
• 12 months:
walks alone
Rate Limiters, or Controllers
• Individual constraints that inhibit or slow
the attainment of a motor skill
• Rapidly changing during early childhood
periods