What do you mean by Cephalocaudal and Proximodistal development?

Psychology 213: unit 4 -- Physical Development in Infancy and Toddlerhood
(9-13-10)

Changes in body size and muscle-fat makeup

Physical growth is very rapid during the first 24 months of postnatal live

"baby fat" rises with a peak at about 9 months; this helps the infant maintain a constant body temperature

Toddlers begin to be more slender; this trend continues into middle childhood

Individual and group differences

Girls, in infancy, tend to be shorter and lighter, with a higher fat to muscle ratio than boys

There are significant individual and group differences in size and rate of physical growth

A good estimate of a child's physical maturity is the skeletal age, a measure of bone development; girls tend to be ahead of boys during the developmental years and reach their fully body size several years earlier

Developmental treads

cephalocaudal trend -- a pattern of growth occurs from the head downward through the body, the head grows more rapidly than the lower part of the body

proximodistal trend -- a pattern of growth occurs from the center of the body outwards, for instance the arms and legs grow faster than the hands and feet

The central nervous system

The brain at birth has billions of neurons -- nerve cells that store and transmit information

Between the neurons are tiny gaps called synapses

Neurons influence each other through the release of chemicals called neurotransmitters that cross the synapse and stimulate receptor sites on the next cell.

Active neurons establish more synapses with other cells; inactive neurons lose their connections, a process called synaptic pruning

About half of the volume of our brain is made up of glial cells which support the neurons and provide myelination, the coating of neural fibers with myelin, an insulating fatty sheath that improves the speed and efficiency of the neuron's signaling of other cells

Cerebral Cortex

largest, most complex, structure in human brain, and last brain structure to stop growing

different regions of the cerebral cortex has associated functions

anatomy of behavior

the Frontal Lobes are the region with the most extended period of development and is responsible for thought, inhibition of impulses, sustained attention, integration of information, planning and analysis of actions, and the functional use of memory

Sensitive periods in brain development

stimulation of the brain is vital during periods of rapid growth

Changing state of arousal

the organization of sleep and wakefulness changes between birth and age 2

Influences on Early Physical Growth

biological: heredity, nutrition, malnutrition

emotional: parental/caretaker love is critical for human growth and development

nonorganic failure to thrive

modification of response to stimuli with repeated presentations

habituation & sensitization

Classical (or respondent or Pavlovian) conditioning

unconditioned stimuli (innate)

unconditioned responses (reflexes)

conditioned stimuli (learned)

conditioned responses (learned)

Operant (or instrumental or reward) conditioning (or learning)

reinforcement

extinction

discrimination

shaping (successive approximations)

Imitation (or modeling or observational learning) as a form of learning

mirror neurons

gross-motor development -- moving in your environment

fine-motor development -- manipulating your environment

hearing (auditory perception)

seeing (visual perception)

integration (intermodal perception)

The physical bodies of infants and toddlers show common growth trends and these trends relate to motor development. There are two important trends: cephalocaudal and proximodistal. The cephalocaudal trend acknowledges a top-down growth trend. For example, infants may use their upper limbs before their lower limbs. The proximodistal trend, on the other hand, acknowledges growth from the center of the body outwards. For example, infants use their arms before they can use their fingers effectively.

Figure \(\PageIndex{1}\): Infant using both feet to interact with a book. . ([1])

Resources on infant and toddler development sometimes mistakenly reference cephalocaudal and proximodistal trends as principles (i.e., Gonzalez-Mena, 2014). The reason they are trends and not principles is that they only describe what typically happens (a trend) as not all infants show motor development that exactly follows these trends. For example, research has shown that some infants will reach for and interact with objects using their feet before they are able to do so with their hands (Galloway & Thelen, 2004; Heathcock & Galloway, 2009), which does not follow the cephalocaudal trend. Figure# is a picture of an infant using both feet to interact with a book while being read to by a caregiver. [2]

[1] Image by Todd LaMarr is licensed under CC by NC 4.0.

[2] “Cephalocaudal trend” from Wikipedia is licensed under CC by SA 4.0.

Motor development occurs in an orderly sequence as infants move from reflexive reactions (e.g., sucking and rooting) to more advanced motor functioning. As mentioned during the prenatal section, development occurs according to the Cephalocaudal (from head to tail) and Proximodistal (from the midline outward) principles. For instance, babies first learn to hold their heads up, then to sit with assistance, then to sit unassisted, followed later by crawling, pulling up, cruising, and then walking. As motor skills develop, there are certain developmental milestones that young children should achieve. For each milestone there is an average age, as well as a range of ages in which the milestone should be reached. An example of a developmental milestone is a baby holding up its head. Babies on average are able to hold up their head at 6 weeks old, and 90% of babies achieve this between 3 weeks and 4 months old. If a baby is not holding up his head by 4 months old, he is showing a delay. On average, most babies sit alone at 7 months old. Sitting involves both coordination and muscle strength, and 90% of babies achieve this milestone between 5 and 9 months old. If the child is displaying delays on several milestones, that is reason for concern, and the parent or caregiver should discuss this with the child’s pediatrician. Some developmental delays can be identified and addressed through early intervention.

Motor Skills refer to our ability to move our bodies and manipulate objects. Fine motor skills focus on the muscles in our fingers, toes, and eyes, and enable coordination of small actions (e.g., grasping a toy, writing with a pencil, and using a spoon). Newborns cannot grasp objects voluntarily but do wave their arms toward objects of interest. At about 4 months of age, the infant is able to reach for an object, first with both arms and within a few weeks, with only one arm. At this age grasping an object involves the use of the fingers and palm, but no thumbs. This is known as the Palmer Grasp. The use of the thumb comes at about 9 months of age when the infant is able to grasp an object using the forefinger and thumb. Now the infant uses a Pincer Grasp, and this ability greatly enhances the ability to control and manipulate an object and infants take great delight in this newfound ability. They may spend hours picking up small objects from the floor and placing them in containers. By 9 months, an infant can also watch a moving object, reach for it as it approaches, and grab it.

Gross motor skills focus on large muscle groups that control our head, torso, arms and legs and involve larger movements (e.g., balancing, running, and jumping). These skills begin to develop first. Examples include moving to bring the chin up when lying on the stomach, moving the chest up, and rocking back and forth on hands and knees. But it also includes exploring an object with one’s feet as many babies do as early as 8 weeks of age if seated in a carrier or other device that frees the hips. This may be easier than reaching for an object with the hands, which requires much more practice (Berk, 2007). Sometimes an infant will try to move toward an object while crawling and surprisingly move backward because of the greater amount of strength in the arms than in the legs.