chapter 6 Early Motor Development Babies Gone Wild

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: Sameside arm and leg extend.

Grasp and STNR Palmar Grasp Reflex Symmetrical Tonic Neck Reflex • Stimulus: Touch palm with finger or object. • Infant starts in supported sitting position. • Response: Hand closes tightly around finger or object. • 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

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 Parachute • Infant starts in supine position. • Infant is held upright. • 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. • 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).