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

• Stimulus: touch face above or below the lips.

• Response: sucking motion begins.

Babinski reflex

• Stimulus: stroke sole of foot from heel to toe.

• Response: toes extend.

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

• Infant starts in supine position.

• Stimulus: turn head to one side, or turn legs and pelvis to other side.

• Response: body follows head in rotation, or trunk and head follow in rotation.

Parachute

• Infant held upright.

• Stimulus: lower infant toward ground rapidly.

• 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