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Psych development
CH 9 Grasping - Development of Manipulative Skills
| Term | definition |
|---|---|
| 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 |
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rmart11
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