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Psych development

CH 9 Grasping - Development of Manipulative Skills

Termdefinition
Sidearm striking is a form of striking where the arm traveled below the shoulder level
Early Sidearm striking No back swing No trunk rotation Facing the ball / chopping
What are some developmental change sin sidearm striking Stand to side of ball Weight to back foot Trunk rotation – blocked to differentiated Power grip vs shake hands grip
How do you think striking ages for adults? When task demands are not high then performance and form will be similar
Prehension is the grasping of an object, usually with the hand or hands
Early grasping infant squeezes an object against the palm without the thumb providing opposition
Power grip the infant uses the thumb in opposition but still holds the object against the palm
precision grip After 9 months of age, infants begin to hold objects between thumb and one or more fingers
Halverson (1931): Gasping Key point The first year sees a transition from power grips to precision grips, but the particular grip used is influenced by the shape and size of the object grasped
Overarm striking is a form of striking where the arm traveled above the shoulder level
Hohlstein (1982): Grasping -The transition from power to precision grips was still evident, but shape and size of the object influenced the specific type of grasp used -By 9 mons of age infants reliably shape their hand in anticipation of an object’s shape as they go to grasp it
The finding that shape and size of the object to be grasped influences the grip used suggests the individual, environment, and the task interact in prehension movements
Newell et al. (1989): grasping -Watched 4- to 8-month-old infants grasp a cube and three cups of different diameters -Found that infants use five types of grip 95% of the time, but type of grip depends on size/shape of object
Butterworth et al. (1997): grasping -Tested infants between 6 and 20 months of age pick up cubes/spheres of different sizes -Confirmed Halverson’s general trend from power  precision grips
Object size greatly influenced the grip selected,
Shape had somewhat less influence on the grip on the grip
The movement selected by individuals is related to to their hand size compared with an object’s size, or movements reflect body scaling
Body scaling is adapting characteristics of the task or environment to the overall body size or to the size of the body component.
Are there sex differences in grasping? No
The influence of object size on grip used supports the idea that the ratio between hand size and object size is important, but the lack of a difference between the boys and girls does not
the ratio between hand size and object size is important, but the lack of a difference between the boys and girls does not? Yes
Newell et al. (1989): Observed 3- to 5-year-olds and adults Found that a relatively constant ratio of hand size to object size determined when individuals chose to use two hands to pick up an object instead of one, no matter what their age
From a young age on we select the grip appropriate for the size, weight, and shape of the object to be obtained
Infants often knock an object before actually grasping it, why? -Dependent on vision -Cant process stimulation at the same pace as an adult
Does grasping need to be relearned with increases in growth? Very stable skill (automative) over the lifespan
What conditions could influence hand configuration? E.g., arthritis, loss of strength in old age, sarcopenia
Early developmentalists proposed that reaching and grasping required seeing both both the object and the hand in the visual field so that vision and proprioception could be matched
Infants are NOT learning to match vision of the hand and arm with proprioception of the movement Infants are very good from the start at reaching in the dark when they cannot see their hand
To reach objects infants learn to control their arms; they learn by doing
Thelen et al. (1993): reaching -Recorded arm movements of four infants longitudinally from 3 weeks to 1 year of age -Infants made the transition from pre-reaching to reaching at 3-4 months of age
Hand-Mouth Movements infants become more consistent at bringing the hand to the mouth rather than to other parts of the face
Bimanual Reaching and Manipulation -Infants in their 1st year alternate between periods when unimanual reaches predominate and periods when bimanual reaches predominate -cannot perform complementary activities with two hands until the second year
when infants are able to maintain postural control Reaching improves
Manual Performance in Adulthood Kauranen and Vanharranta (1996) Scores on all of the hand measures declined after age 50; the reaction, movement, and tapping times slowed, and coordination declined
Manual Performance in Adulthood Hughes et al. (1997) Declining manual performance was associated with loss of strength and upper joint impairment resulting from musculoskeletal disease
Some aspects of older adults’ reaches slow down, putting them at a disadvantage in making sequential movements, but accuracy of manipulation is stable, especially on well-known tasks
Created by: rmart11