Sensations- How do they occur with infants? Prenatal or postnatal?

Infants learn about the world around them through their sensations and perceptions, or interpretations of their senses (Gauvin, 2009). Sensations are well developed at birth, and although it is difficult to measure the amount or level of perception and sensation, there are some measures universally used (Gauvin, 2009). Visual preference is when an infant is presented with two stimuli and the amount of time looking at each stimuli is calculated (Gauvin, 2009). It is assumed the longer time spent on a stimuli, a difference is distinguished by the infant (Gauvin, 2009). A second tool used to measure perception and sensation is Violation of Expectation (Gauvin, 2009). Something unusual or different from the natural setting is presented and if the infant engages in a different (atypical) behavior, then it is assumed the baby has some knowledge or understanding about the stimuli and its purpose (Gauvin, 2009). Many other measurements are also utilized to determine the ability to distinguish, prefer, or recognize stimuli with infants.
One factor that can impair measurements is habituation to stimuli. An infant habituates to stimuli when repeated exposure to the stimuli occurs and the reaction decreases to that stimulus (Gauvin, 2009). Decreased response occurs when the ability to habituate to the stimuli is achieved, and this impacts the studies of sensory and perception (Gauvin, 2009).
Most senses are developed by birth. Increased ability to discriminate and utilize these senses occurs after birth. At one week an infant is able to discriminate between black and gray visually, and by eight months they have approximately 25% of the visual ability of adults (Gauvin, 2009). Hearing is present and can be tested immediately after birth (Gauvin, 2009). In fact, some studies have even tested hearing prenatally. By the end of the first two years, a child can discriminate between sounds, pitch, and tone (Gauvin, 2009).
Infants are further capable of intermodal perception, or using information from more than one sensory system and integrating the information (Gauvin, 2009). By one month babies can integrate vision and touch, and at four months they can integrate visual and auditory stimuli (Gauvin, 2009).

Obviously the sensations are developed by birth and merely fine tuned post natal, allowing the infant to categorize and associate information from the sensory systems into their knowledge constructs. In fact, it is possible by the amount of prenatal sensory information and the formation of neural networks that the neonates are able to learn prenatally.

Valerie Poling

References:
Gauvin, P. (2009). Child Psychology: A Contemporary Viewpoint, 7th ed. In C. U. HASOP, Psychology Human Prenatal Development (pp. 3-36). McGraw-Hill Primis.