Chapter 6 Early Motor Development

What constraints exist during reflexive period?

- Structural - Functional - Environmental Physical - Environmental Sociocultural - Task: goals, rules, equipment

Describe later infancy

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

What are purposes of reflexes?

1. Built-in responses to facilitate survival. 2. Reflexes allow "dialogue" with environment. 3. Reflexive movements result in sensory consequences 4. Reflexes provide building blocks for future movement.

What are two ways an individual may deviate form typical?

1. Exhibiting a reflex when the individual should not 2. Not exhibiting a reflex when the individual should.

What are the three types of infantile reflexes?

1. Primitive Reflexes 2. Locomotor Reflexes 3. Postural Reactions

What are the three locomotor reflexes?

1. Stepping 2. Swimming 3. Crawling

What might a reflex that persists well after the average age indicate?

A pathological cerebral condition (neurological problems).

Infantile Reflexes

An involuntary, stereotypical movement response to a specific stimulus; the term refer specifically to such responses seen only during infancy. There are three types of infertile reflexes: 1. Primitive reflexes 2. Locomotor reflexes 3. Postural reactions

Locomotor Reflexes (Moving in Place)

Appear much earlier than the corresponding voluntary behaviors and typically disappear months before the infant attempts the voluntary locomotor skills.

Spontaneous Movements (stereotypies).

Are infants' movements that occur without any apparent stimulation.

When do postural reactions begin?

Around 4 months Help maintain posture in changing environment Initially are similar to reflexes; than are incorporated into general repertoire.

Infants tend to activate both the muscle for flexing the limbs (flexor) and the muscles for extending the limb (extensors) what is this called?

Co-contraction. In contrast, adults move by alternating flexor and extensor muscles.

Labyrinthine Righting Reflex (Derotative Righting vs. Parachute).

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 turn and head follow in rotation. Parachute - Infant is held upright - Stimulus: lower infant toward ground rapidly - Response: legs and arms extend

Postural Reactions (moving upright in the world)

Help the infant automatically maintain posture in a changing environment. Some of these responses keep the had upright, thereby keeping the breathing passages open.

Labyrinthine Righting Reflex

Infant is supported upright Stimulus: tilt infant Response: Head moves to stay upright.

Symmetrical Tonic Neck Reflex

Infant starts is supported sitting position Stimulus: Extent head and neck or flex head and neck Response: Arms extend and legs flex, or arms flex and legs extend.

Asymmetrical Tonic Neck Reflex

Infants start in supine position Stimulus: turn head to one side Response: Same-side arm and leg extend.

Moro Reflex

Infants start in supine positon Stimulus: Shake head (Example: by tapping pillow) Response: Arms, legs, and fingers extend; then arms and legs flex.

What happens when there is a deviation from the typical pattern and typical execution of the responses?

It may signal a problem.

Supine Position

Laid on his back

When do primitive reflexes disappear?

Newborn exhibit strong reflexes at birth; but these reflexes tend to lose their strength over time until they disappear around the fourth month.

Do infant reflexes involve the whole body?

No, only single muscle or a specific group of muscles.

When do reflexive movements occur?

Quickly after onset of stimuli Sometimes theses responses occur only when the body is in a specific position An infant does not have to think about making reflexive movements, it just occurs automatically.

How can you tell between primitive reflexes and spontaneous movements?

Reflexes are responses to specific external stimuli, whereas spontaneous movements do NOT result from any apparent external stimuli. Reflexive movements are specific and often localized, whereas spontaneous movements lead to be nonspecific and generalized The same stimulus will elicit a specific reflex over and over gain.

What does spontaneous arm movements resemble?

Resemble reaching

Stepping Reflex

Stimulus: Place soles of feet on flat surface Response: Legs move in walking pattern

Palmar Grasp Reflex

Stimulus: Touch palm with finger or object Response: Hand closes tightly around finger or object

Supine Kicking: In analyzing the position and timing of leg segments in these kicks as well as muscular activity in the leg muscles, what did they discover?

That supine kicking was not random but rhythmical, and the kicks had a coordinated pattern, they resembled the position of adult walking.

What is the current theory of spontaneous movement?

They are building blocks, similar to some voluntary movement.

What is the original theory of spontaneous movements?

They are extraneous, no purpose

Do postural reactions disappear?

They do not literally disappear.

If the reflexes appear and disappear at an age close to the average what are they considered?

Typical infant development

Primitive Reflexes (around from the beginning)

When a newborn infant grasps an object placed in her hand, she does so automatically and without conscious thought. It is an involuntary response to a specific stimulation that is often mediated by lower brain centers.

Are there reflexes that are only present during infancy?

Yes, This is called infantile reflexes