One of the most mysterious and highly debated areas of psychological research is that of the human infant. While each one of us undoubtedly went through infancy and the subsequent stages of human development, we, as adults, are commonly unable to recall many events, thoughts, or emotions from our earliest few years. This phenomenon, called infantile or childhood amnesia, has greatly influenced the study of infant memory and cognitive development overall.
The general school of thought regarding memory, until relatively recently, was that the infantile brain was not yet developed enough to store and retrieve memories, or that they were just fleeting and transient, accounting for our inability to recall them in adulthood. While this theory hasn’t been disproved completely quite yet, due to more thorough research in the field, it is no longer as widely accepted as the best explanation in the psychological community (Hayne, 2003, pp.
121-150). Whereas historically infant brain development was often studied by speculating in terms of what could be learned about the brain function of the elderly, in the past 20 years, experiments involving visual preference tests, conditioning procedures, deferred imitation, object permanence, paired-comparison techniques, and event-related potentials (ERP) measured via electroencephalograph (EEG) suggest that infant memory is better developed than previously thought (Byrne, 2003, pp.
254-255). Even with such advances in study of infant memory and cognitive development, scientists have been unable to reach a solid conclusion about the cause of childhood amnesia. In addition to the physical explanation mentioned above, there is evidence to suggest the validity of a few new theories on the subject. One of the most plausible of these theories involves the difference in perception and language developments between infancy and adulthood.
Proponents of this theory believe that early childhood memories are still stored in the brain, but adults are unable to access them because they were encoded through infant perception and in terms of an infant’s pre-linguistic thoughts. While these early memories are likely to have been retrieved over the course of one’s life, as one develops, the memories’ “content has probably been updated –perhaps many times – to reflect more recent circumstances (Muir, 2000, p.
25)” Though there are still many questions surrounding the workings of memory during infancy, such research has certainly enlightened the field as to what the human brain is capable of, even during the first couple of years in life. Not only does infant memory research help adults understand their pasts, but better understanding how the brain develops early on is likely to be the key to unlocking more of its potential.
Since the infant’s brain and related sensory organs are still adjusting and forming, particularly during the first year to two years of life, it stands to reason that certain developments might be encouraged during that time, while the organs are still forming. To a degree, this concept has already been applied. Such organ adaptation methods have been used successfully to treat such medical conditions as infant cataracts, generally a genetic condition.
After surgery is performed on the infant’s eye to remove the cataract, the unaffected eye is covered up to allow the bad eye to adapt back to normal vision. This method of sight recovery does not work in the case of adult cataract surgery, as the development of the eyes and brain are already established (Kumar, 2003, pp. 565? 566). According to studies and experiments within the last 10 years, an infant’s brain can also be encouraged to adapt to using additional areas for processing and memory, and to build more synapses than would otherwise develop.
Language and communication, generally controlled by the left hemisphere of the brain, can be expanded to involve the right hemisphere also when an infant, deaf or of normal hearing, is taught American Sign Language (ASL) within the first 10 months of life. Visual stimuli, like signing in ASL, are received in the right hemisphere and then processed in the left, which is responsible for storing and interpreting language (Emmorey, 2002, pp.
271-314). The use of both sides of the brain to process language for communication trains the infant for more elaborate linguistic interpretation that can later in life, it would follow, be applied to other types of mental processing. In the case of infants born with hearing loss, learning ASL as soon as possible is important to normal development and communication.
Infants with normal hearing start to babble audibly by 7-10 months and while deaf infants might not verbally babble in as complex a manner as their hearing peers, those taught ASL will actually manually babble in signs around the same age if not quicker, trying to imitate the signs of the parent. An infant usually produces his first sign in ASL around the same time as his hearing peers, though some parents claim they see the first sign 1-3 months prior to the first words in hearing infants heard at 7-9 months.
It may be difficult to be sure of whether deaf children taught ASL actually have an advantage over hearing children when it comes to their first words and, “native signers have higher rates of vocabulary growth than peers learning spoken language (Marschark, 1993, p. 106),” it should be noted that the hands are quicker to develop dexterity than the mouth, so it is not difficult to believe that an infant would have an easier time communicating with his hands than with his mouth at an early age.
Despite this possible head start on vocabulary development when taught ASL early on, Marschark (1993) goes on to report a common misconception about deaf children is that they are, “Literal and concrete in both their language and cognitive functioning… relatively limited in their abilities to grasp complex, abstract, or nonliteral [sic] concepts, even when those concepts involve nonverbal domains. ” (p. 184)
Given what has been discovered since then about the brain and memory in infancy, and that ASL might be taught early in development to expand cognitive functioning and to compensate for lack of particular sensory input, surely new research will allow us to find that we can eliminate such misconception from the realm of possibility.
References
Bremner, G. , Slater, A. , & Butterworth, G. (Eds. ). (1997). Infant development: Recent advances. East Sussex, UK: Psychology Press Ltd. Byrne, J. H. (2003). Learning and memory (2nd ed. ). New York: Macmillan Reference USA.