Anyone who has watched the magical changes that occur from the birth of a child through infancy to early childhood has witnessed rapid development of the brain, sensory systems and movement patterns AKA motor coordination.

A child’s first two years are often called the ‘sensory motor period.’ The sensory and motor systems are intricately linked and dependent on each other. We use our sensory systems to explore and learn about the world. We use our motor systems to move us to new sensory experiences. But what connects the sensory and motor systems at the beginning of development?

In this blog, we talk about how sensory processing and simple automatic motor patterns, called primitive reflexes, work together to support early development.

Let’s review sensory processing, the individual sensory systems and primitive reflex patterns.

Sensory processing

Sensory processing is the ability to take in information through individual sensory systems, combine the information, make sense of it and respond, in good time, or ignore it if it’s not relevant.

The sensory systems

The sensory systems are:

  • Movement/balance
  • Position
  • Touch
  • Sight
  • Sound
  • Smell and taste.

Primitive reflex patterns

Primitive reflexes are automatic motor responses to sensory stimuli. Primitive reflexes are activated by a specific sensory stimulus in a particular place, such as the palm of the hand. The result is a specific, simple, predictable movement pattern such as closing the hands (known as the Robinson grasp reflex). Once activated, the reflex movement cannot be stopped or changed by our thoughts. It is completely automatic.

How sensory processing and primitive reflexes work together

In the example above, a sensory stimulus activated a primitive reflex pattern and a simple movement resulted. We will use this Robinson grasp primitive reflex pattern to demonstrate the inter-relatedness of sensory processing and primitive reflex patterns.

From shortly after birth to around four months of age, Robinson grasp is active. When a touch stimulus contacts the palm of the hand, close to the base of the fingers, a specific movement pattern occurs the hands close to make a fist. The pattern is symmetrical which means both hands move together even if the touch sensory stimulus is applied to one hand.

During this time, baby begins to explore objects with his hands. Robinson grasp allows baby to hold the object and bring it in for closer inspection. After a while, the hand opens, and the object is dropped. Over time, baby encounters a variety of textures through touch. This experience provides information and the brain creates a touch sensory memory file. Touch information to the hands is recognized as safe and familiar and the Robinson grasp reflex pattern is not activated as often. The infant begins to move in different ways, outside the primitive reflex movement pattern. Movement is led by intention; the movements become free, flexible and can be changed. Integration of Robinson grasp allows the development of the complex movements needed to build fine motor skills.

Primitive reflex patterns do not completely disappear but integrate into a child’s complex movement repertoire. Robinson grasp is only activated when an immediate, automatic response is necessary to protect the child, such as when he is falling and must grasp something to prevent injury.

If there is a problem with sensory processing, Robinson grasp will remain active and complex voluntary movement will be limited. The child must rely on the simple, predictable, unchangeable primitive reflex pattern. This delays development of the motor cortex in the brain, limits sensory processing, and interferes with fine motor skills in many areas such as self-care and using tools/toys.

If there is a problem primitive reflex pattern (such as failure to activate, incorrect or incomplete patterning or cross wiring of other reflex patterns), motor development will be negatively impacted. The resulting limitation will also affect a child’s ability to engage in a full range of sensory experiences and fine motor activities.

The effects of sensory processing difficulties and retained reflex patterns

Robinson grasp reflex pattern is vital for safety but, if it doesn’t integrate, causes limitations for more skilled hand use. To develop the ability to engage with toys and use tools and learn from that engagement, a child must be able to tolerate a variety of textures on many areas of the palm and fingers.

Fine motor skills like buttoning, tying shoes, drawing and writing will be impacted. There will be problems with in-hand manipulation, tactile discrimination and the grading needed for the fine motor control for letter formation. Learning about texture, size, shape and other properties will not occur or will be delayed. These skills form the foundation for fine motor and self-care skills.

Robinson reflex grasp pattern is symmetrical meaning that both hands activate even if the stimulus touches one hand. This causes a problem in knowing we have two distinct sides of the body and two separate hands. If both hands move together, the brain cannot differentiate between them. This impacts development of a dominant hand and the sense of midline and causes confusion between left and right. These problems affect directionality, bilateral coordination, reading and writing (seen in confusion and reversals).

Next steps…

We have described the impact of just one retained primitive reflex and the sensory and motor components. There are more than 20 primitive reflex patterns and their corresponding sensory activators which impact motor development. Retained reflexes and related difficulties in sensory processing impact emotional and cognitive development too. We will discuss these areas in future blogs.