Critical and sensitive periods
In terms of cognitive development, we can distinguish several sensitive and critical developmental stages during which a special type of environmental stimulus facilitates the process. A critical stage is a relatively short period that starts and ends at quite precise moments. During this period, the body is vulnerable to influences like those caused by certain aspects of nutrition. Such examples are the negative effects triggered by an iron or iodine deficiency in the initial stages of brain development. During a critical stage, these is an increased sensitivity to environmental stimuli; however, if there is no stimulus, then it is going to be difficult, if not impossible, that an aspect of the brain performance be expressed later in life. Therefore, if malnutrition hinders metabolical processes at a certain age, there is the risk of a long-term side effect on cognition.
On the other hand, a sensitive period is seen as a window of opportunities in which the brain is sensitive to a certain type of stimuli. For example, language is much more easily acquired during the first ten years of life. Although particular functional aspects are gained without difficulty during a sensitive period, an ability can still be achieved at a later age, albeit not as easily and not at the same level of competence and good command.
The alleged differences between sensitive and critical stages of development are usually subtle, and the stated appreciations vary from one worker to another, and according to discipline. Some of them noticed that children fall short at a certain developmental stage if they lack the stimulation characteristic to a critical window of opportunities. At the opposite end, others believe that there are only sensitive periods, and that a lack of stimulation does not produce difficulties which could not be overcome later, even with a greater effort.
At least, as far as nutrition is concerned, there is good evidence regarding the critical stages of development. As the brain develops rapidly during pregnancy, an inadequate diet can limit the development of important aspects related to brain structure. The argument is that, since it is the mother’s diet that provides the nutrient blocks from which the baby’s brain is made, if during a period of fast brain growth an aspect of nutrition is inappropriate, permanent brain damage can occur.
Read MoreDyslexic children present a series of common characteristics that manifest in their way of reacting, their personality and school performances. Even though all children are different and not all of them present all the characteristics, they still have many of them in common.
Dyslexia is a special learning disability, whose symptoms change as the child grows and develops. From as early as the preschool stage, it is possible to notice small details that could make us suspect that a child is dyslexic. Between ages 6 and 11, the symptoms are more obvious, or, at least, better known. From the age of 12, learning disorders become more clear.
For a child to be dyslexic, he doesn’t need to show all the symptoms described below. At the same time, it doesn’t mean he is dyslexic for only showing one of them.
Characteristics at personal level:
Lack of attention. Due to the great intellectual focus he must sustain in order to overcome his characteristic difficulties of perception, the child will present a high level of fatigue, which will result in variable attention. Thus, acquiring literacy will require a great effort on their part if they are not interested and they find no intrinsic motivation that could attract their attention.
Lack of interest for learning. His school grades and general performance are usually low, which causes demotivation and low self-esteem for the student. Some children may be very hard-working, and they still won’t see any result to their efforts. This will often make them become uninterested, work less and eventually fall behind.
Personal maladjustment. Sometimes we find dyslexic students showing features that denote an emotional imbalance; these features include low self-esteem and behavioral problems, even violence.
A feeling of insecurity and obstinacy.
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