Sensitive periods is a term coined by the Dutch geneticist Hugo de Vries

Hugo de Vries

Hugo Marie de Vries ForMemRS was a Dutch botanist and one of the first geneticists. He is known chiefly for suggesting the concept of genes, rediscovering the laws of heredity in the 1890s while unaware of Gregor Mendel's work, for introducing the term "mutation", and for developing a mutation...

 and adopted by the Italian educator Maria Montessori

Maria Montessori

Maria Montessori was an Italian physician and educator, a noted humanitarian and devout Catholic best known for the philosophy of education which bears her name...

 to refer to important periods of childhood development.

Montessori believed that every human being goes through a series of quantum leaps in learning

Learning

Learning is acquiring new or modifying existing knowledge, behaviors, skills, values, or preferences and may involve synthesizing different types of information. The ability to learn is possessed by humans, animals and some machines. Progress over time tends to follow learning curves.Human learning...

 during the pre-school years. Drawing on the work of de Vries, she attributed these behaviors to the development of specific areas of the human brain

Human brain

The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...

, which she called nebulae. She felt this was especially true during the first few years of life, from birth (or before) to the time of essentially complete development of the brain, about age 6 or 7. Montessori observed several overlapping periods during which the child is particularly sensitive to certain types of stimuli

Stimulus (physiology)

In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....

 or interactions. She describes these as "sensitive periods", a phrase coined by de Vries during his studies on animals.

According to Montessori, during a sensitive period it is very easy for children to acquire certain abilities, such as language

Language

Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication...

, discrimination of sensory stimuli, and mental model

Mental model

A mental model is an explanation of someone's thought process about how something works in the real world. It is a representation of the surrounding world, the relationships between its various parts and a person's intuitive perception about his or her own acts and their consequences...

ing of the environment. Once the sensitive period for a particular ability is past, the development of the brain has progressed past the point at which information can be simply absorbed. The child must then be taught the ability, resulting in expenditure of conscious effort, and not producing results as great as could be produced if the sensitive period had been taken advantage of. Montessori was not very specific in her published works about the precise number, description, or timing of these sensitive periods. However, in her lectures to teacher trainees she set out several periods with the approximate ages to which they applied. More importantly, she believed, adults should observe the behavior and activities of children to discover what sensitive periods they are in.

Periods by age

MontessoriMom uses the following chart (cited by permission):

Age	Sensitivity
Birth to 6 years	The absorbent mind: the mind soaks up information like a sponge. Sensory learning and experiences: the child uses all five senses Sensory system A sensory system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory receptors, neural pathways, and parts of the brain involved in sensory perception. Commonly recognized sensory systems are those for vision, hearing, somatic...  - touch, taste, smell, sight, and hearing - to understand and absorb information about his or her environment.
1.5 to 3 years	Language explosion: a child builds his or her future foundation for language.
1.5 to 4 years	Development and coordination of fine and large muscle skills Motor skill A motor skill is a learned sequence of movements that combine to produce a smooth, efficient action in order to master a particular task. The development of motor skill occurs in the motor cortex, the region of the cerebral cortex that controls voluntary muscle groups.- Development of motor skills... , advanced developing grasp and release skill spawns an interest in any small object.
2 to 4 years	Very mobile with greater coordination and refinement of movement, increased interest in language and communication (they enjoy telling stories), aware of spatial relationships, matching, sequence and order of objects.
2.5 to 6 years	Works well incorporating all five senses for learning and adapting to environment.
3 to 6 years	Interest in and admiration of the adult world: they want to copy and mimic adults, such as parents and teachers.
4 to 5 years	Using one’s hands and fingers in cutting, writing and art. Their tactile senses are very developed and acute.
4.5 to 6 years	Reading and math readiness, and, eventually, reading and math skills.

AMI descriptions

The Association Montessori Internationale describes the sensitive periods differently in their teacher-training lectures, arranging them by focus rather than by chronology.

Language

This period runs from birth through approximately age 6. During this period the child is extremely sensitive to vocal sounds and to movements of the vocal apparatus. Out of all the sounds in an infants environment, the infant will be attracted to that of human sounds. Deprivation of language stimuli during this period can lead to severe language defects. Without stimulation, the synapses

Chemical synapse

Chemical synapses are specialized junctions through which neurons signal to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow neurons to form circuits within the central nervous system. They are crucial to the biological computations that underlie...

 of Broca's area

Broca's area

Broca's area is a region of the hominid brain with functions linked to speech production.The production of language has been linked to the Broca’s area since Pierre Paul Broca reported impairments in two patients. They had lost the ability to speak after injury to the posterior inferior frontal...

 and related language-processing areas of the brain will literally waste away.

Order

The sensitive period for order operates most actively between roughly the ages of one and three years. In this period, the child is organizing a mental schema

Schema (psychology)

A schema , in psychology and cognitive science, describes any of several concepts including:* An organized pattern of thought or behavior.* A structured cluster of pre-conceived ideas....

 for the world. In order for firm conclusions to be drawn about the world, the child must be able to impose an order on it in a way that makes sense to the child and is consistent with the observed world of the child. If this need is not met, the child's ability to reason and learn will be precarious, since she may not be able to consider her conclusions reliable.

Sensory refinement

This period lasts from birth to age 4. A child takes in information about the world through his senses. As the brain develops, it becomes able to discriminate between relevant and irrelevant sensory stimuli. The most efficient way to accomplish this is for the brain to pay attention to all sensory stimuli. The most repetitive (and therefore most important) of these will strengthen neural pathway

Neural pathway

A neural pathway, neural tract, or neural face, connects one part of the nervous system with another and usually consists of bundles of elongated, myelin-insulated neurons, known collectively as white matter...

s, while the less common, although initially detected, will not provide enough brain activity to develop sensitivity to them. By age 4 or so, the brain has finished its "decision-making" about which stimuli are relevant, and worth attending to. Other stimuli will be ignored. This period, then, is important for helping the child attend to differences in sensory stimuli, which in turn can lead to a greater ability to impose a mental order on his environment.

Refinement of motor skills

This period encompasses the time between roughly 18 months and 4 years of age. By the beginning of this period, the child's gross motor skills are generally rather well developed. At this point, the continuing development of the cerebellum

Cerebellum

The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...

 and motor cortex

Motor cortex

Motor cortex is a term that describes regions of the cerebral cortex involved in the planning, control, and execution of voluntary motor functions.-Anatomy of the motor cortex :The motor cortex can be divided into four main parts:...

allow the child to increase her fine motor skills. Activity on the part of the child which focuses on fine muscle control (writing with a pencil, picking up and setting down small objects, and so on) will allow the child's muscular skills to develop to a quite advanced level. After this period, neural control of the muscles is relatively fixed, and improvement in fine motor skills comes only with considerable effort.

Sensitivity To small objects

This period, between roughly 18 and 30 months, might be viewed as a consequence of the overlapping of the previous two. As a consequence of the child's attention to sensory stimuli, combined with an interest in activities requiring fine motor coordination, the child takes an interest in observing and manipulating very small objects, which present a greater challenge to the senses and coordination than large ones.

Social behavior

From about 2.5 through 6 years, the child, having become relatively stable in his physical and emotional environment, begins to attend to the social environment. During this time, in an attempt to order this aspect of her surroundings, the child attends closely to the observed and expected behavior of individuals in a group. This attention and ordering will allow her to move through the social environment in a safe and acceptable way. Children who are, for whatever reason, largely or entirely deprived of social interaction during this period will be less socially confident and perhaps more uncomfortable around others, a feeling which may take substantial effort to overcome.

External links

• Association Montessori Internationale