In-Depth Notes on Manipulative Skills Development

Definition: Manipulative skills involve fine motor skills essential for handling objects, crucial for various daily activities.
Human Uniqueness: Humans exhibit unique manipulation abilities due to physical adaptations such as the opposable thumb, allowing complex grip and grasping movements.

Influencing Factors: Rate limited by strength, limb size, hand size. As we age, conditions like arthritis can make manipulation painful so we change how we do it

Prehension: The act of grasping objects
- Halverson (1931) proposed 10 phases of grasping development:
  - Transition from power to precisions grips in the 1st year
1. Birth: No contact with objects.
2. 1 month: Limited contact.
3. 2 months: Grasping with the whole hand.
4. 3 months: Adjusting hand position when grasping.
5. 4 months: Grasping with the thumb on top.
6. 5 months: Grasping with fingers only.
Hohlestein (1982) : Object size and shape influence type of grasp; By 9 months, infants shape hand to match objects as they reach for them.

Definition: Grip movements are body-scaled, meaning that the ratio of hand size to object size allows individuals of varying sizes to perform similar movements.
Key Observations:
- Larger object size has a greater impact on grasping method than shape.

Vision significantly influences grasping over the lifespan:
- Younger Infants: Often contact objects before attempting to grasp.
- Adults: Shape their hands in anticipation prior to contacting an object.
Grasping remains stable and does not need to be relearned, although conditions like arthritis can affect hand configuration in older adults.

Early reaching is characterized by random arm movements, which require visual and proprioceptive feedback for accurate maneuvering.
- The initial limitation in reaching is learning to control arm movements.
Bimanual Reaching: Defined as the use of both hands to manipulate objects:
- Development Stages:
- At 2 months, infants show bilateral reaching but not in a complementary fashion.
- By 12 months, cooperative manipulation begins, leading to more complex interactions by age 2.
Postural Control: Reaching improves significantly after infants develop trunk control, generally around 6-7 months.

Decline Post-50: Manual performance typically experiences decline, resulting in slower movements and decreased coordination:
- This decline can impact daily activities and independence in older adults.
- Precision tasks, such as handwriting, remain accurate but show slight loss in coordination.

Foundation of Catching: Catching involves intercepting and retaining objects using the hands, which becomes more proficient with practice.
- Initial attempts are often rigid and poorly executed, with children not always tracking the ball.
Proficiency: Proficient catchers adjust their body and hands to absorb the impact of the object effectively.

Anticipation is critical for successful catching, requiring the ability to predict the trajectory and arrival of the object:
- Factors affecting success include the object's speed, direction, size, and trajectory height.
Developmental Rules:
1. Increased movement complexity reduces accuracy.
2. More distance to interception lessens accuracy.
3. Larger objects are easier to catch than smaller ones.
The perception-action perspective suggests that information necessary for catch success is inherent in the environment:
- Catching involves subconscious discovery of rates and spatial awareness through practice.

Older adults experience reduced speed and accuracy in catching tasks but can improve with focused practice.

Manipulative skills are crucial for human interaction and vary with development and aging, indicating a complex interplay between physical capabilities, cognitive anticipation, and hand-eye coordination. Infants develop these skills progressively and maintain them through adulthood, with notable challenges arising in older age due to physical limitations.