Grasping is a motor skill that allows interaction with the environment through the hands. This ability to hold and manipulate objects is a complex set of movements that evolves from simple, reflexive actions at birth to highly controlled motions. This development is important for early exploration and the later acquisition of complex daily tasks.
The Newborn Grasping Reflex
A newborn is equipped with the palmar grasp reflex, an automatic response where the fingers close around an object that strokes their palm. This reflex is strong enough in the first few weeks of life to support the infant’s body weight, though testing this is not recommended.
The palmar grasp is a primitive reflex, likely tied to an evolutionary need to cling to a caregiver for safety. This action is controlled by the lower centers of the brain and is not intentional. The reflex typically disappears around five to six months as higher brain centers mature and voluntary muscle control emerges.
Developing Voluntary Grasping
As the palmar reflex fades, a shift occurs toward purposeful grasping, marking a step in fine motor development. Around four to five months, a baby uses a crude whole-hand motion, known as a raking grasp, to sweep objects toward themselves. They may use both hands to reach for an object before developing a one-handed approach around six months.
Between six and nine months, control becomes more refined. A milestone in this period is the development of the pincer grasp, where the infant learns to pick up small items using the tips of their thumb and forefinger. This ability signifies a leap in dexterity and hand-eye coordination. By one year, a child can release objects voluntarily, stack a couple of blocks, and point with their index finger.
Types of Grasps
Human grasping can be categorized into two functional types used throughout life: power grips and precision grips. The distinction lies in whether the goal is to apply force or to achieve delicate manipulation.
A power grip is used when strength is the primary requirement. In this grasp, the object is held firmly against the palm, and the fingers and thumb apply counter-pressure. Examples include holding a hammer, gripping the handle of a suitcase, or opening a jar. The muscles of the forearm and hand work together to create a stable hold.
A precision grip is employed for tasks that require control and dexterity. This grip involves holding an object between the tips of the fingers and the thumb. Writing with a pen, turning a key, or threading a needle are activities that utilize a precision grip. This form of grasping allows for fine adjustments, relying more on the small muscles within the hand.