Early Motor Development chapter 6 Early Motor Development

Babies Gone Wild! Interacting constraints allow young infants to learn to drive. Click image to view video

Early Motor Behavior Reflexive or spontaneous (Clark, 1995): Reflexive: stereotypical responses elicited by specific external stimuli Spontaneous: movements not caused by known external stimuli

Spontaneous Behaviors Original theory: extraneous, no purpose Current theory: building blocks, similar to some voluntary movements Examples Spontaneous arm movements (resemble reaching) Spontaneous kicking (resembles adult walking)

Infant Kicks Click image to view video

Reflexes Reflexive movements occur quickly after onset of stimuli. They involve single muscle or specific group of muscles (not whole body). They cannot be extinguished at any one time. Persistence may indicate neurological problems.

Purposes of Reflexes Built-in responses facilitate survival. Reflexes allow “dialogue” with 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.

Grasp and STNR Palmar Grasp Reflex Stimulus: Touch palm with finger or object. Response: Hand closes tightly around finger or object. Symmetrical Tonic Neck Reflex Infant starts in supported sitting position. Stimulus: Extend head and neck or flex head and neck. Response: Arms extend and legs flex, or arms flex and legs extend.

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: Legs move in walking pattern.

Constraints What constraints exist during the reflexive period? Structural Functional Environmental physical Environmental sociocultural Task: goals, rules, equipment Click to add notes

Reflexes Go through the reflexes listed in the text. What voluntary behaviors might they be linked to? What makes you think so?

Later Infancy Voluntary control of movements Understanding of environment, objects in environment Meaningful interactions with others Postural reactions

Postural Reactions Begin around 4 months Help maintain posture in changing environment Initially similar to reflexes, then 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 is held upright. Stimulus: Lower infant toward ground rapidly. Response: Legs and arms extend.

Motor Milestones Fundamental motor skills Building blocks (leading to complex motor skills) Cumulative, sequential Specific movements that lead to general actions

Locomotor and Posture Motor Milestones 2 months: Lifts head in prone position. 3 months: Lifts shoulders (turns head). Click image to view video (continued)

Locomotor and Posture Motor Milestones (continued) 5 months: Rolls over, sits unsupported. Click image to view video (continued)

Locomotor and Posture Motor Milestones (continued) 7 months: Gets on hands and knees. 8 months: Creeps on hands and knees. Click image to view video (continued)

Locomotor and Posture Motor Milestones (continued) 9 months: Pulls to stand; cruises furniture. Click image to view video (continued)

Locomotor and Posture Motor Milestones (continued) 10 months: Stands alone. 12 months: Walks alone. Click image to view video

Rate Limiters, or Controllers Individual constraints that inhibit or slow attainment of a motor skill Rapidly changing during early childhood

Rate Limiters What important rate limiters during infancy may control development of the following? Crawling Reaching Walking

Development of Postural Control and Balance in Infancy Rate limiters for posture and balance appear to involve coupling of sensory information and motor response. Infants continuously calibrate sensory motor response (Chen, Metcalfe, Jeka, & Clark, 2007).