a. (“commando crawl”): moving on hands and abdomen
a. What relevant evidence do you see in infants who can pull to stand but cannot walk?
i. Coordination-not coordinating enough to make that movement to lift foot and go
ii. Enough strength to stand but not quite enough to push off and walkNot enough balance-static balance is fine, but haven’t developed dynamic balance
a. Early walking patterns tend to maximize stability and balance.
b. Arms are in high guard.
c. Feet are out-toed and spread wide apart. (increasing base of support; early in development and then later in the elderly)
d. Independent steps are taken. (without holding onto anything)
e. Rate controllers are strength (to support body on one leg) and balance.
a. Stride length increases.
b. Base of support is reduced.
c. Pelvis is rotated.
d. Opposition (arms to legs) occurs.
e. **Double knee lock pattern – extension at heel strike and push off (another marker-if the knee is extended on both the heal strike and push off-marker of proficient walking)
a. Occurs 6 to 7 months after walking starts.
b. Defined by
i. 50% phasing of the legsflight phase followed by single support (either foot on the ground-flight phase
a. Patterns help increase stability and balance. (make up for any balance or stability that you have lost)
b. Decreases appear in stride length, range of motion, number of strides, .speed
c. Rate controllers are balance and strength. (at older age you can lose balance and strength)
d. Exercise can allow seniors to run for years! (Paul Spangler ran marathons until the age of 95)
a. Stability over mobility: return of “old behaviors”
b. Arms in high guard
c. Limited range of motion
d. Short stride length
e. Little rotation
f. Starting to get the flight phase but they are unsure so they regress a little bit
A. Less Stability, MORE Mobility
a. Increased stride length
b. Planar movement (arms and legs are moving in the direction that they want to run, trying to keep their movements all in one plane)
c. Narrow base of support
d. Trunk rotation (more trunk rotation)
e. Opposition of arms and legs
f. As you increase your stride length-pelvis rotates more-upper body rotates more
Pictures in the book-running-beginning and advanced running
a. Children often begin simple jumping before age 2.
b. Individuals can perform either vertical or horizontal (standing long) jump.
a. Hopping starts later than jumping.
b. Early characteristics include the following.
i. Support leg is lifted rather than used to project body.
ii. Arms are inactive.
iii. Swing leg is held rigidly in front of body.
a. Jumping: force production (to project body off ground)
i. Force production (to project body from one foot to same foot)
ii. Balance (to land on one foot)
iii. Force absorption (to land repeatedly on same leg)
a. symmetric: alternating step-hops on one foot, then on the other.
A. Proficient Galloping, Sliding, Skipping
i. Knees give on landing. (absorbing the force)
ii. Movements are rhythmic.
iii. Heel–foot or forefoot landings prevail.
–Individual can lead with either leg.
–Arms can be used for other purposes (e.g., clapping).
i. Coordination (uncoupling legs)
ii. Differential force production (legs performing different tasks)
b. Sliding: coordination (turning to one side)
c. Skipping: coordination (ability to perform two tasks with one leg)
A. Developmental Changes in Overarm Throwing: upper arm action
ii. Aligned but independentLagging
A. Progression of overarm throwing in childhood
a. Throwers do not achieve same step for each body component at same time.
b. Some step combinations are observed more frequently than others.
c. Not everyone reaches highest step in each component.
d. Differences are observed between the sexes in throwing skill.
a. Older adults demonstrate moderately advanced steps.
b. Differences are observed between the sexes.
c. Ball velocities are moderate.
d. Musculoskeletal constraints might influence movement patterns used.
e. Change is slow, involves decline (and more variability) in performance, and is typically related to control rather than coordination.
a. Performer strikes ball with foot.
b. Kicker must have perceptual abilities and eye-foot coordination to make contact (kicking a moving ball is difficult for children).
a. Various body parts can be used.
b. Implements can be used.
c. Mechanical principles are similar for all striking tasks.*Principles can be applied to other striking tasks
a. Chopping motion (elbow extension)
b. Little leg and trunk movement
a. Sideways preparatory stance and long step
b. Differentiated trunk rotation
c. Horizontal swing through large range of motion (arm extended before contact)
d. Sequential movements
a. Sequences for foot and trunk in overarm throw can be used.
b. Trend is toward use of trunk rotation (none, then blocked, then differentiated).
c. Plane of swing progresses from vertical to horizontal.
d. Grip changes from power grip to “shake-hands” grip.
e. Elbows are held away from body and extended before contact.
i. Studied tennis players’ first serves.
ii. Studied older servers at moderate levels.
iii. Two former teaching professionals were categorized at the highest levels (i.e., maintained coordination of movements).
a. Performer applies force to an object in order to project it.
b. Examples? Throwing, kicking, striking
a. Developmental sequences can be used as checklists.
b. Individuals are in a developmental step if a majority of executions (usually out of five attempts) fall into that category.
c. Observation should be conducted from the appropriate direction.
d. Side views show forward step, trunk action, lagging.
e. Rear views show arm angles.
a. What makes humans unique in performing manipulative skills?
a. What drives infants to transition from random arm movements to purposeful reaches?
a. Does learning to reach involve learning to visually match hand and object or learning to control the arm?
-At 2 months, infants show bilateral arm extension and reaching.
-Around 4.5 months, infants reach for objects with both arms (usually one hand reaches and grasps object first).
-During year 1, infants alternate between predominantly unimanual and predominantly bimanual reaching.
-By 12 months, we see pulling apart and insertion actions.
-Early in year 2, infants use objects as tools.
-After 18 months, infants manipulate objects cooperatively with both hands By end of year 2, we see complementary activities.
i. Reaching improves when infants can maintain postural control
ii. What postural constraints could serve as limiters to the rate of development of reaching?
Balance being off
a. Ideally, objects are caught in the hands so they can be manipulated
b. Needing to intercept an object makes catching more difficult
c. Children initially position arms and hands rigidly, sometimes trap ball against chest
d. *Children sometimes turn their head away or close their eyes
a. Model of constraints and catching
i. Consider various objects to catch and various task and environmental constraints for catching tasks.
ii. What makes some catching tasks more difficult than others? Speed of object, shape of object, wind
iii. For comparisons , task and environmental constraints must be consistentThe number of catches in a set of attempts must be scored
a. For comparisons, task and environmental constraints must be consistent.
b. The number of catches in a set of attempts can be scored.The developmental sequence can provide information about the movement process
i. interception success is often related to ball size, speed, trajectory, and other task and environmental constraints.
ii. Why might studies on coincidence-anticipation reflect limits of perception more than real-world catching skill?
Changing what would normally happen
i. Two characteristics of person–environment system for catching involve constant patterns of change
1. Invariants: stable patterns
2. Expanding optical array: visual pattern that expands or constricts on the retina
ii. Invariance in moving sideways was investigated through the constant bearing angle strategy.
i. Little research is available.
ii. Catching might be influenced by factors affecting movement speed or ability to reach.
iii. Older adults are somewhat less accurate and more variable on coincidence-anticipation tasks.Older adults can improve with practice
a. How might sensory disabilities act as rate limiters to development? Of what skills?
No feeling in feet can inhibit ability to walk. If there is an eyesight problem, sports could be a problem. Hearing impairment can limit learning development. Lack of proprioceptive system can affect balance and give trouble walking.
i. Sharpness of sight or the amount of detail that can be seen in an object
ii. In the first month, acuity is 20/400 (5% of adult level).
iii. Infant can differentiate facial features at 20 inches.
i. Declines in vision have implications for skill performance and everyday living tasks.
ii. Older adults need more light in dim environments.
· Clouding of the eye’s lens
· Initial symptoms:
2. Faded colors
3. Need for more light to read
· Risks increased by: smoking, alcohol use, long-term exposure to sun’s ultraviolet rays
· Don’t confuse with Senile miosis
****Wear your sunglasses!!!****
· Decreased ability accommodate near objects with age (40+ yrs. old)
· Loss of elasticity in lens, decreased strength of ciliary muscles
· Result is trouble seeing nearby objects clearlyBifocals
1. Comparison of images received by eyes
i. Lack of eye–hand coordination
iii. Under- or overreaching for objectsUnusual head movements
i. Requires perception of depth and distance
ii. Information can come from
1. retinal disparity
2. motion parallaxoptic flow
1.Infants may use depth and motion more than edges.
2.Children refine figure-and-ground and whole-and-part perception, especially under difficult conditions.
3.Preadolescents reach adult levels (adult sensitivity goes beyond that needed to perceive objects in the everyday world) Infants explore manually and orallyPurposeful manual exploration improves in childhood
1. Newborns are sensitive to object shape.
2. Newborns perceive faces. Do they identify mother’s face more readily than others? yes
3. Children refine their ability to detect subtle changes in object orientation.What aspects of learning in the classroom involve object orientation? Learning to write, reading
1. Located in the inner ear
2. Rotational motion
a. Semicircular canals (angular accelerometers)
3. Linear accelerationOtolith organs (utricle and saccule
i. Receptors probably function prenatally
ii. Newborns respond to touch and can locate touches to the face.
iii. Vestibular apparatus functions by age 2 months, if not earlier.
i. Newborns can feel touches.
1. For what activity in the first hours after birth is perception of touch important?
ii. Perception of touch location improves in early childhood.Thresholds for discriminating between one touch and two nearby touches improve in childhood
awareneness of body’s two distinct sides
Improves in late childhood
i. Directionality improves in late childhood.Transposing right and left improves in adolescence
i. (preferring one eye, ear, hand, or foot over the other):
1. Infants show preferences
2. Handedness is established around age 4 years
3. No evidence shows that pure dominance is necessaryChildren with developmental delay often struggle to cross midline of body with hand and arm to complete a task on opposite side. (Laterality)
a. Orientation or position of objects
-Infants’ threshold for sound is higher than adults’ but allows detection of normal speaking voice.
-Rapid improvement is seen in the first week.
-At 3 months, infants hear low-frequency sounds well. (the oscillation is slower)
-Infants would listen more to music than speech because it is slower and has more rhythm to it.
-Infants will listen to mother’s voice over others because there is familiarity.
a. Auditory changes with aging
i. Hearing loss (presbycusis) is more frequent in older adults.
ii. Some loss might have a physiological source. (degredation in receptors or other physiological problems)
iii. Some loss might result from lifelong exposure to environmental noise.
iv. Absolute and differential thresholds generally increase.
v. Hearing amid a noisy background is more difficult.
a. Infants can discriminate basic speech sounds at 1 to 4 months of age.
b. Accuracy in discrimination improves in childhood.
c. Older adults may have difficulty with speech perception due to declines in sensitivity to pure tones.
a. Three properties give rise to patterns: Time, Intensity,Frequency
b. Temporal patterns are perceived by age 1 year.
c. Intensity changes are detected between 5 and 11 months.
d. Simple frequency patterns are discriminated under 6 months of age.
· More complex patterns are detected by age 1 year. Improvements are made throughout childhood in perceiving longer and more complex patterns.
a. Infants possess basic perceptual ability.
b. Subtle discrimination and complex judgment improve in childhood.
c. Adults may have difficulty perceiving if the senses are impaired.
i. Newborns turn toward a sound.
ii. Discrimination of patterns across these modalities improves in childhood.
iii. A task is easier for children if visual pattern is presented first. What does this say about how young children use their senses? Vision is most important.
i. Infants seem to relate objects they can see to objects they have mouthed.
ii. Recognition of an object across modalities is shown in the first year, but selecting items that match across modalities comes later.Finer discriminations improve in childhood (visual-first presentation is easier
i. Perception improves in childhood (knowledge of object names is relevant).
ii. More research is needed.
i. Intermodal coordination begins at birth.
ii. Performance of matching tasks and subtle discrimination improves throughout childhood and adolescence.Accuracy of performance is related to order of presentation (easiest versions present visual information first
A. Contemporary views
a. Perceptual-motor activities are important.
i. They give children experience in performing skills based on perceptual information.
ii. They reinforce concepts such as shapes and directions.Ex. Putting shapes into right hole
i. It is the affordance that is perceived.
1. Affordances involve what the environment permits, given the capabilities of the performer
2. They are perceived directly, without cognitive analysis of object characteristics
a. Warren (1984) related stair height to leg length.
b. In older adults, affordances of stairs were related more to strength and flexibility than leg length
c. No single model has been found to apply over the life span
- Grip movements are body scaled (Newell, Scully, Tenenbaum, & Hardiman, 1989)
-Method: examined adult and children grasping
1. Key is hand size relative to object size
2. Object size plays role in gripping patterns
3. Children use same grip patterns as adults
4. More research is needed in infancy
-Ratio of hand size to object size is consistent for transitioning from using one hand to using two hands to pick up object.
Lower the basketball goal, different sized balls, changing bats in baseball, smaller courts or fields, smaller desks and chairs in classrooms
-Infants use trial-and-error exploration
-Infants relate objects to other objects and to surfaces
- Affordances involve relationships between objects
-Self-generated opportunity for perceptual learning exists (tool use facilitates perceptual development)
a. the challenge is to control the many degrees of freedom of movement at the various body joints.
i. We can stabilize our heads on our trunks.
ii. We can stabilize head position in space.
a. Balance improves with practice in responding to perturbations (Woolacott, 1986)
b. Exercise programs that stress strength and balance reduce falls (Campbell et al. 1997)
Only jumping vertically
- One-foot takeoff or landing
-No or limited preparatory movements
-Inefficient arm movements
1. Used for balance instead of to help propel the body forward
a. “wing” and “parachute”
i. No trunk rotation
ii. Minimal trunk rotation
iii. Total trunk rotation
A. Developmental changes in overarm striking: elbow action in ball contact phase
i. Very small or very large angle
ii. Intermediate angle (2–89 degrees)
iii. Ideal angle (90–119 degrees)
Do catchers keep the vertical optical acceleration of the ball close to zero?
1. Target and performer are stationary
2. Measured with Snellen eye chart (>3 yrs old)
3. What does 20/50 vision mean? It means you see at 20 feet what someone else sees at 50 feet.
1. Ability to see the detail in moving objects
2. CNS estimates an object’s direction and velocity
3. Ability of the ocular-motor system “to catch” and “to hold” an object’s image on the eye’s fovea long enough to see detail
4. Continues to improve from 6 – 20 yrs. old
· Loss of central vision
· Dry – breakdown of light sensitive cells in macula
· Wet – new blood vessel behind retina leak and destroy macula with an end result of blindness
· Age-related maculopathy is the precursor to AMD
· Can’t drive and reading is more difficult
1. Muscle spindles
a. Gauge the amount of tension within the muscle
b. Senses how the muscle is stretched
2. Golgi tendon organs- Monitors tension in the muscle
3. Joint receptors - “Limit detectors”
a. are patterns in space or time that do not differ across modalities. Examples? Proprioception in gravity, visual perception of objects in gravity. Seeing and hear someone talking and knowing the voice is coming from their mouth.
i. 50% phasing of the legs (Clark, Whitall, & Phillips, 1988) (equal sharing among the legs, 50% in the swing phase and 50% in the stand phase)period of double support (both feet on the ground) followed by period of single support
a. Out-toeing increases.
b. Stride length decreases. (taking smaller steps)
c. Pelvic rotation decreases.
d. Speed decreases.
e. Objects are used as balance aids. (canes, walkers-additional support piece to use)
i. Balance-flight phase have to land and take off
ii. Taking off and landing-muscle strength-more force to get body off the ground-force production and absorption-and muscle strength to catch body weight and absorb the force coming down
iii. Increase and improved balance
a. Many forms
i. Underhand (one- or two-hand)
iii. Overarm (one- or two-hand)
b. Most common in sport: one-hand overarm
a. movement pattern):
i. developmental sequences
-None or forward–backward movement
- Differentiated rotation
A. Developmental Changes in Overarm Throwing: Backswing
ii. Shoulder flexion
iii. Upward backswing
iv. Downward, circular backswing
Developmental Changes in Overarm Throwing: foot action
i. No step
ii. Homolateral step
iii. Short contralateral step
iv. Long contralateral step
A. Developmental Changes in Overarm Throwing: forearm action
i. No lag
iii. Delayed lag
i. Upward toss
ii. Late drop from chest height
iii. Late drop from waist heightEarly drop from chest height
1. Arm drop
2. Arm abduction
3. Arm opposition
1. No short step, ankle flexed
2. Long step, ankle extended
3. Leap and hop
A. Developmental changes in overarm striking: Spinal and pelvic range of motion
i. Rotation of less than 45 degrees
ii. Rotation of 45 to 89 degrees
iii. Rotation of 90 degrees or more
Developmental changes in overarm striking: racket action
i. No racket lag
ii. Racket lag
iii. Delayed racket lag
i. Studied iron shot (did not require maximal force).
ii. Older golfers reach peak force earlier in swing.
iii. Older golfers may need to exert more force than younger golfers for same shot.
iv. Most older golfers were just as accurate as younger golfers.
a. Proficient performance demonstrates the mechanical principles.
b. Developmental trends are toward proficient mechanical performance.
c. Performer uses forward step and more trunk rotation.
d. Trunk rotation is differentiated.
e. Projecting limb shows increasing lag.
f. Not all individuals reach highest developmental steps.Older adults appear to maintain coordination of ballistic movements fairly well
i. Method: Filmed infants (16-52 wks) grasping a 1 inch cube
ii. Result: Transition from power to precision grips
Defined 10 phases of prehension development
iii. Limitation of study: Imposition of one task, one set of environmental conditions
i. Method: Replicated Halverson’s study but used objects of different sizes and shapes
ii. Result: Object size and shape influence type of grasp
*by 9 months, infants shape hand to match object as they reach
a. What is the role of vision in grasping?