I)Neural and Sensory Competencies: The most critical time to ensure optimal sensory functioning is during prenatal development. At 18 weeks, nearly all cortical neurons have formed and migrated to their genetically preprogrammed locations. Human infants are born with fully functional sensory and motor systems. Myelin sheaths form rapidly around neuronal axons during infancy, assisting sensory responses and the coordination of activities across brain regions by vastly increasing the speed of neural impulse conduction. Visual processing is served by two neuronal systems: cortical pathways and more primitive subcortical pathways. Infant visual behavior is thought to be primarily controlled by the subcortical during the first two months of life.
ii) Visual Sensory System: Some aspects of newborn visual sensory processing, such as peripheral acuity, are fairly well-developed in the newborn infant.
The ability to make oculomotor adjustments is also fairly well developed, allowing the infant to perceive distance. Several aspects of the ocular system are extremely underdeveloped in newborns. Newborn visual acuity is significantly lower than that of adults, but it improves to adult levels by the age of eight months. The ability to detect variations in light intensity, or contrast sensitivity, is also lacking in young infants, but it is sufficient to detect coarse boundaries between common objects and spatial layouts in close proximity. Finally, by the third month of life, the infant has developed the ability to detect the direction and velocity of object motion.
iii) Auditory Sensory System: By 28 weeks of prenatal development, the human fetus responds to sounds. The ability of newborn infants to detect low frequencies is mature at birth; however, the ability to detect higher frequencies is not mature until the age of 6 months. Many aspects of auditory sensory processing do not reach adult performance levels until late childhood.
iv) Chemical and vestibular senses: Infants' tactile and vestibular sensory systems develop slightly before their more distant-sensing visual and auditory systems.
v)Visual Perception: (Object Perception) Newborns probably have the ability to detect and analyze features in parallel, and they have some "tools" to organize features for object perception. However, some tools take many months to develop as babies learn more about the world around them.
vi) Space perception: Even very young babies can understand how objects move, but they may not use as many of these clues as an adult would when processing what they see. Once they can move around on their own, the way they see space changes a lot. This is because accurate perception requires cues from both the moving object and the moving observer.
vii )Face Perception: Within 6 days of birth, babies will look longer at attractive faces than unattractive faces, as judged by adults. They will also follow a moving face pattern farther than a scrambled face pattern.
Face processing improves very quickly in the first few months of life, when babies start to see different kinds of faces around them.
viii) Auditory Perception: One of the most basic and well-studied parts of language perception is an infant's ability to tell the difference between basic sounds, called phonemes, in his or her native language. Even though babies are sensitive to all phonemes in all languages when they are young, this changes as the baby grows up.
At 14 months, babies can tell the difference between words that sound the same but mean different things, like ball and doll. They can also tell the difference between words that sound the same but mean different things, like bin and din, when shown a picture of an object that is supposed to represent the word.