Development of Reach and Grasp

Question 1

At birth, an infant can move his attention from one object to another. As he matures, he goes through a period of “___________ looking,” but is able to disengage from an object again by about ____ months.

Answer 1

obligatory

4

Question 2

Limited smooth pursuit is present at birth and begins to improve at ____ weeks. Infants track objects well by ____ months and use the head and eye together by ____ months.

Answer 2

6
3
5

Question 3

At ____ months, head-arm movements are strongly coupled. Over the next 2 months, head and arm movements begin uncoupling, allowing for more _____________.

Answer 3

2

flexibility

Question 4

By ____ months, infants gain trunk postural stability, providing stable base for the emergence of ____________.

Answer 4

4

reaching

Question 5

Rudimentary Reaching Skills (pre-reaching):

• newborn: moves arm when visually fixated on an object, open hand
• ____ months: frequency of reaching decreases, hand fixes
• ____ months: frequency of reaching increases, hand open, infants acquire skill in aiming movements and become realistic in the reaching

Answer 5

2

3

Question 6

Reaching movements are ___________ triggered.

Answer 6

visually

Question 7

Infant Reaching:
- ___ to ___ months: reaching occurs in several steps, bimanual reaching may dominate, elbow may be locked, final approach is awkward, reaching becomes visually guided

Answer 7

4 to 5

Question 8

Infant Reaching:
- ___ months: reaching becomes smoother (fewer steps and straighter approach), unilateral reaching may begin, elbow is used

Answer 8

6

Question 9

Infant Reaching:

- ___ to ___ months: coordinated/complementary bimanual reaching (transfers objects), controlled release

Answer 9

8 to 9

Question 10

At the end of the first year __________ guided reaching diminishes. Young infants initiate reaching using a ___________ strategy to aim the hand at the target and then switch to a ____________ strategy to make corrective movements for grasping.

Answer 10

visually
ballistic
feedback

Question 11

T/F: reaching changes a lot from 9 months to 7 years

Answer 11

False, it changes little

Question 12

___ year olds use ballistic reaching strategies (lots of feedforward)
____ year olds constantly monitor and control their reaches with a closed loop strategy (lots of visual feedback)

Answer 12

5

7

Question 13

By ___ to ___ years, children combine strategies to improve efficiency and reduce the amount of attention required.

Answer 13

9 to 11

Question 14

Name the 4 intrinsic factors influencing reaching in infancy.

Answer 14

age
experience
postural control
developmental delay

Question 15

Name the 3 extrinsic factors influencing reaching in infancy.

Answer 15

task demands/extrinsic factors
vision
coordination

Question 16

Rudimentary Grasp:

• newborn to ___ months: reflexive grasp, hand is open during reaching (extensor synergy)
• ___ months: hand is fisted during reaching
• ___ months: open hand when infant is visually fixated on targer

Answer 16

2
2
3

Question 17

Infant Grasp:

• ___ to ___ months: infants begins to use vision to correct hand trajectory, palmar grasp emerges
• ___ to ___ months: infants expect to see hand and performance is disturbed if vision of hand is blocked; visual information is used to adjust grip configuration, radial palmar grasp

Answer 17

• 4 to 5

- 5 to 6

Question 18

Infant Grasp:

• ___ to ___ months: opening of hand during reaching is related to size of object, pincer grasp emerges
• ___ to ___ months: grasp is initiated earlier in the reach, timing is similar to adults, pincer grasp is well-developed

Answer 18

• 8 to 9

- 12 to 13

Question 19

Grasping in Childhood:

• ___ years: grip and load force are negatively correlated, tendency to over-shoot target (lots of feedforward)
• ___ years: children begin to use an anticipatory control strategy for grasp (grip and load force become positively correlated, less overshooting)
• Adults: grip and load forced are programmed in parallel to prevent slips and avoid squeezing too hard, integration of feedback and feedforward strategies

Answer 19

• 2

- 4

Question 20

Describe the 2 major features of development of fine motor function.

Answer 20

1. control of the hand as the terminal device for reaching and grasping
2. object manipulation and release

Question 21

Cognition and Object Exploration:

• ___ to ___ months: find partially hidden objects, explores objects with hands and mouth
• ___ months: object permanence and separation anxiety
• ___ months: begins to use objects correctly, imitates gestures

Answer 21

• 6 to 7
• 8
• 12

Question 22

Cognition and Object Exploration:

• ___ to ___ months: stacks 2 blocks, adapts reaching to the weight of the object
• ___ months: stack 3 blocks, understand objects go together (cup and saucer)
• ___ years: stacks 6 blocks, sorts by shape/color, begins pretend play
• ___ years: completes puzzle with 3-4 pieces

Answer 22

• 13 to 15
• 18
• 2
• 3